Window Repair & Weatherization Guidebook
by Architectural Heritage Center – September 2013
Window Repair and Weatherization Guidebook
TO GET A USER FRIENDLY VERSION OF THIS GUIDE WITH ILLUSTRATIONS GO TO:
A Handy Guide for Owners of Portland, Oregon Homes
Bosco‐Milligan Foundation/Architectural Heritage Center
With support from the Irvington Community Association
Image Courtesy of Patty Spencer
TABLE OF CONTENTS
Introduction .. 3
Windows and Local Design Guidelines .. 4
Windows and the Secretary of the Interiors Standards 4
Windows and energy loss 5
R‐Values and U‐Factors . 6
Air Infiltration .. 6
Typical Double Hung Wood Window (Diagram) . 7
Typical Window Issues and Their Repairs 7‐12
Deterioration ... 8
Condensation .. 8
Air Infiltration .. 8‐9
Weather Stripping . 9‐10
Weights and Sash Cords 10
Locks and Latches .. 11
Paint . 11
Racked Windows . 11‐12
Storm Windows and Alternatives to Window Replacement 12‐13
Interior Storm Windows 12
Exterior Storm Windows .. 12
Insulated Glass Systems 13
Other Types of Historic Windows and Their Weatherization Solutions .. 13
Casement Windows .. 13
Metal Fame Windows . 13
Weatherizing Using Window Treatments . 14‐15
Shutters . 14
Curtains . 14
Films .. 14
Awnings .. 15
Historically Sensitive Replacement Windows .. 15‐16
Adding New Windows Where There Are None .. 16‐17
Basement Windows 17
What if the Original Windows Were Already Replaced?..................................... 17
Portland, Oregon Area Window Repair and Weatherization Professionals . 20
This booklet was created to identify issues common to original windows in vintage and historic homes in Portland, Oregon and to offer solutions for how these issues can be resolved without seriously impacting historic character. In many instances, the tips in this booklet may be applied to other parts of the Pacific Northwest where similar building materials are commonplace.
Why Should I Keep and Repair My Old Windows?
Because the original windows were designed specifically to fit your home. Not just in shape and size but in materials too.
Because the original windows have character defining features that you love, such as wavy glass, real divided light sashes, and ogee lugs.
Because you appreciate the longevity of irreplaceable old growth wood and high quality craftsmanship.
Because you recognize value in being able to repair something when it needs repair, rather than replacing it because it cannot be repaired.
Because original windows really can be made as energy efficient as any replacement.
Because you can save money and energy by repairing your original windows whereas you may never recoup the expense of replacement windows or be able to repair them should they need work.
Through the use of this booklet and the resources therein, owners of historic homes of all shapes and sizes will find that in most circumstances, original windows can be repaired and weatherized, and when such work is performed in combination with other weatherization measures can result in significant energy savings. Such repair and weatherization work also costs less than window replacement. In addition to cost and energy savings, by keeping original windows intact, usable and repairable materials are kept from the waste stream and the depletion of natural resources is prevented, all the while maintaining the historic character of homes, neighborhoods, and communities.
This booklet should serve as a guide for:
Property owners in National Register Historic Districts whose properties are subject to Historic Design Review for any changes to the exterior of the structure(s).
Property owners of properties that are individually listed in the National Register of Historic Places and which are subject to Historic Design Review for any changes to the exterior of the structure(s).
Property owners in Conservation Districts whose properties may be subject to Historic Design review for any changes to the exterior of the structure(s).
Owners of older homes who want to preserve or restore the historic character and architectural integrity of their homes, even if they are not designated historic. 3
50 years of age is generally regarded as the point in which a home or other structure may be considered historic. According to the City of Portland, more than 62% of existing structures in the city meet this standard. In some parts of the city, however, that percentage is even higher. In Northeast Portland, for example, 83% of buildings meet the 50 year threshold. The issue of preserving the historic character of Portland neighborhoods is, therefore, a citywide issue. It is not limited to a few parts of the central city.
Although we have attempted to provide the most up to date information on window repair and weatherization for historic homes, following the recommendations in this guide does not guarantee approval by any current or future Historic Design Review commission.
PLEASE NOTE: In Portland, if you have a building in a historic district and plan on altering your windows beyond simple repairs, you will trigger a required Historic Design Review. Replacement windows are generally not permitted unless they are beyond reasonable repair.
Windows and Local Design Guidelines
Before embarking on any project related to windows in a historic home, you should have a thorough understanding of local historic design guidelines and how they may be applied to your home and/or historic district. In Portland, Oregon some historic districts have historic design guidelines that are specific to those individual districts, while others only refer to the Secretary of the Interiors Standards (explained below). In both cases it is important that you investigate what guidelines apply to your home, prior to performing any work on the exterior, including the windows.
Windows and the Secretary of the Interiors Standards
The Secretary of the Interiors Standards for Rehabilitation and the National Park Services Guidelines for Rehabilitating Historic Buildings serve as the rule‐of‐thumb for any work on a historic building. In general, the Standards and Guidelines recommend that as much as possible, original historic materials be retained, maintained, and/or repaired.
In regards to windows, the Guidelines specifically recommend installing compatible interior or exterior storm windows to improve energy efficiency. In instances where the original windows cannot be repaired or are missing, the Guidelines recommend installing compatible and energy‐efficient replacement windows that match the appearance, size, design, proportion and profile of the existing historic windows and that are also durable, repairable and recyclable. In addition retrofitting historic windows with high‐performance glazing or clear film is not recommended unless it is determined that the historic character of the windows can be maintained.
Always consult your local jurisdiction for advice prior to starting any window related project on a designated historic home, whether individually listed, part of a historic district, or part of a conservation district.
Windows and Energy Loss
For more than two decades, original single paned wood windows have been cast as the enemy when it comes to heat loss and energy consumption in our homes. But the fact remains that windows are not the sole or even the primary culprit in this regard. In fact there are several other factors that need addressing before window replacement should even be considered. This is especially true in our historic districts, where windows are often considered as defining features of houses built prior to the 1960s. The fact that windows are significant to the architecture of a home frequently leads to contentious battles between well‐meaning homeowners and local landmarks commissions that review exterior alterations to historic properties. Simply put, window replacement is most often not the most effective solution for saving energy or money. There are several other areas where energy can be conserved while still maintaining the historic character of a house.
Source: U.S. Department of Energy
R‐Values and U‐Factors
R‐Values are a measurement of the resistance to heat flow. A higher R‐Value indicates higher insulating properties. The more insulation that is properly installed will increase the R‐Value, and when combined with air sealing will normally make the home more energy efficient. R‐Values are generally not applicable to windows, which are meant to add light to a buildings interior, not to act as an insulator.
U‐Factors are the inverse of R‐Values and are the rating commonly applied to windows. The U‐Factor of a window is the measure of the rate of heat transfer through that window. A lower U‐Factor indicates a more energy efficient window.
Air infiltration is the most common reason for energy loss in a historic home and for the purpose of this report will be used to refer to the ability of air to pass through the walls and/or around the windows of a home. Before any work is performed on the windows, air infiltration should be addressed. Tips for addressing air infiltration can be found in the Typical Window Issues portion of this booklet.
Typical Windows in Portland Area Homes
Most historic homes in Portland have windows that fit into one of the following categories. Each window is made up of one or more sashes the framework that holds the glass panes in place. Figure 2 identifies some of the common elements of a window and the areas in which weatherization measures can be most effective.
Double hung wood windows are the most common type of window found in older and historic Portland area homes. They are meant to open from both the bottom and the top in order to provide proper ventilation.
Casement windows can be wood or metal framed but rather than opening up and down, the window sash opens outward. This is the second most common window type in Portland.
Fixed windows are those that do not open, such as some very large picture windows or some attic windows. Fixed windows can be either wood or metal framed.
Hopper windows tip outward from the top of the sash and are either wood or metal framed.
Sliding windows open and close by sliding one of the sashes and are either wood or metal framed.
Jalousie windows consist of glass louvers and are usually metal framed. 6
Multi‐light windows refers to the number of panes of glass in a sash. For example, a double hung wood window may have nine panes of glass in the top sash and one in the bottom sash. This would be referred to as a nine over one multi‐light window.
Typical Window Issues and Their Repairs:
Before you begin work on any historic window, it is important that you understand and address potential lead paint issues. Any building or house built prior to 1978 may have lead paint. Lead paint can become a hazard during any sort of window repair or replacement. Consult with your local authorities about how to address lead paint concerns and remember to work lead safe.
Decades of exposure to the extremes of Pacific Northwest weather and the lack of regular maintenance can lead to a need for window repairs. In the following section several window issues and their remedies are discussed. You should also refer to the National Park Services Preservation Brief 9, which identifies many wood window repair issues and how they can be effectively addressed.
If well maintained, historic wood windows can last as long as the rest of the house. In the Northwest, windows are often made of old‐growth clear grain wood (often fir), as opposed to modern wood windows that are finger‐jointed or made of much younger wood that is more easily damaged by the weather. The good news is that these old windows can most often be repaired, even if they look deteriorated or even rotted. Before considering replacing any historic wood window, it is important to examine it closely to determine if the window can be repaired. A window repair professional can provide insight or in many instances you may be able to make such a determination yourself.
Window deterioration is mainly caused by water infiltration and poor maintenance. It is important that you maintain your windows just as you would any household appliance or HVAC system. Maintaining your windows will help minimize potential weather damage caused by the moist climate of the Pacific Northwest. In general, water penetrates in the same areas where air leaks occur (Figure 2). Making sure that these areas are properly caulked or puttied and that all finished surfaces are smooth, will help minimize window deterioration caused by moisture.
The areas most impacted by moisture, and therefore more susceptible to rot, are the sill, the joints at the lower corners of the upper and lower sashes, and the joints where the sill and jambs meet. The good news is that these areas can usually be repaired. Loose joints can be re‐glued and rotted sections of a sash or sill can be repaired with epoxy (do not use automobile body filler), or new sections can be cut to replace the area that is rotted. Preservation Brief 9 offers further details on how to perform such repairs yourself. In many instances such repairs on homes that are designated historic or part of a historic district, will not require Historic Design Review. As with other repairs or renovations, always check with your local jurisdiction. Relying on the opinion of a contractor as to whether or not a project requires Historic Design Review is not advised in this or any project that involves alterations to a designated historic home.
Condensation forms when warm areas of a window such as the interior side of a window sash, come in contact with cold air from outside. This can occur with any type of window, including storm windows or even newer replacement windows if a seal is broken. The resulting droplets of water can run down the window surface creating areas of standing water that can then seep into loose joints or unfinished surfaces and cause deterioration. The formation of condensation is directly related to the presence of air infiltration. Mitigation measures are discussed below.
Air Infiltration/Leakage 8
There is perhaps no greater issue with historic windows than the amount of air that is able to infiltrate a building from around their perimeter. Such infiltration leads to cool air entering the home making the window feel drafty. In order for any window (new or old) to truly be energy efficient, air leakage must be minimized. The biggest culprits in this area are around the entire window opening and around the window sashes. It is important that both of these areas are
properly sealed in order to diminish air infiltration issues. Other areas where air can infiltrate a home are the sash weight pockets (inside the window frame and casing) and where the glass and sash frames meet. Replacing windows will not automatically fix air infiltration issues.
There are several measures that can be taken to address air infiltration in historic windows. Caulking around the entire exterior of the window frame (where the casings and house siding meet) is an important first step. In areas where there are larger holes or gaps between the siding and the window frame, it is possible to add foam filler or backing material to fill the void, before sealing it with caulk. On the interior, installing sash pulley covers is an affordable way you can help reduce the amount of air coming through the weight pockets and into the homes interior. Replacing or adding new glazing compound is also an effective way to minimize air leaks and it can lessen window rattling.
Weather stripping historic windows can be one of the most effective yet least expensive methods of minimizing air infiltration. It can also be an effective tool against noise infiltration another reason why people often wish to replace their original windows. Weather stripping is typically installed around the perimeter of the window sashes. In most cases a homeowner can install weather stripping themselves, but window repair professionals also perform such work. To be fully effective, weather stripping must not have any breaks around the perimeter.
Weather stripping comes in a variety of forms and materials, including foam, vinyl and metal. Types of weather stripping include: compressible foam, vinyl v‐flex, compressible felt, bronze strips, and zinc strips. The type you use depends upon the application (see below). If you have irregular openings, you can also use a product known as "rope caulk" that can be removed and re‐used as necessary.
Weather Stripping for Sliding Applications
The term sliding applications refers to weather stripping that can be used along the sides of window jambs, where friction occurs. The spring metal type of weather stripping, for example, is tacked to the window jambs. This type of weather stripping is perhaps the most effective and durable, but is more expensive.
Weather Stripping for Compression Applications Compression application means that the weather stripping is compressed when a window is closed. Foam and felt are the most common and inexpensive types of compression application weather stripping. These products are adhered to the surface on which they are used and are not for sliding applications. Foam and felt are therefore 9
Compression weather stripping on a wood casement window.
Image Courtesy of Jim Heuer.
most effective at the top and bottom of double hung windows or for use around casement windows. Keep in mind that foam and felt do not have a long lifespan as they can deteriorate when exposed to moisture. They are also usually visible when the window is open.
Weights and Sash Cords
One of the most common complaints against historic windows is that they wont open or close properly because the window ropes (sash cords) and weights are either broken or have detached. This is another affordable fix that can usually be completed by a homeowner or through a window repair professional.
In the Pacific Northwest, double hung windows are the most common type found in historic homes. This means that not only should the window open from the bottom, it should also open from the top as well. When operating properly, such windows can be used to provide natural ventilation throughout a home. When the window sash cords break or come untied, the sashes become out of balance, leading to opening/closing difficulties. In order to repair the sash cords and re‐connect the weights, you must first gain access to the cavities where they are located. Many historic double hung wood windows have an access door cut into the window jambs. These doors are often screwed or nailed in place. Once removed, the weights and ropes should be able to be accessed without removing the interior window casings. Unfortunately, in some instances, there are no access doors and the interior casings must be removed in order to gain access to the weights and sash cords. In such cases you might consider screwing the casings back into place after you have made repairs, rather than nailing them, in order to make them easier to remove in the future.
Once you have access to the weights cavity you can install new sash cord (or chain) available at most hardware stores. New sash cord will last for decades but you must make sure you tie the cord to the weights securely, so they do not fall off after you have put things back together. Never paint sash cords as it will only lead to additional problems opening and closing the windows.
Painted windows can create major complications for this process. Paint can hide the location of the access doors. Many window repair professionals encourage paint removal, especially along the window jambs, in order for proper ongoing repair. This can increase the time and expense of such a project, but it makes future maintenance and/or repair of the windows much easier. Remember to always work lead‐safe and to use proper care when using chemical paint strippers or heat guns to remove paint. 10
Example of a properly knotted sash cord.
Image Courtesy of Patty Spencer
Locks and Latches
Poorly working or broken locks and latches can also be a common problem with historic windows. Locks and latches are not just for security purposes. On typical double hung windows, the lock mechanism pulls the two sashes tightly together minimizing air leakage at the meeting rail. Lock or latch screw holes that are deteriorated can be repaired using an epoxy filler that, when hardened, can be re‐drilled so locks and latches can be re‐installed. Re‐using the original locks and latches is recommended as they are usually made of higher grade materials than newer locks. Paint can be removed from old hardware using a variety of techniques that are affordable and can be completed by a homeowner.
Depending on where it is located, paint can be one of your historic windows biggest enemies. Most window repair professionals do not recommend painting the sash jambs as that frequently leads to sticky windows. Weve all heard of windows being painted shut. That is because jambs were painted, along with the sash frames. In such instances, the first step in repairing sticky windows is to cut through the paint using a painters tool. Paint can also be removed using chemical strippers or a heat gun, along with a paint scraping tool. Once paint is stripped from a window it can then be sealed with a high quality wood sealant or coated with a varnish that does not create the stickiness of paint and maintains the unpainted wood finish that was typically original to the house. You can also rub paraffin wax on the sides of the sash frames so that they will slide up and down more easily.
IMPORTANT! Before you begin work on any historic window that has been painted, you must understand and address potential lead paint issues.
Any home built prior to 1978 may have lead paint. In Oregon, consult the Oregon Health Authority if you have concerns about how to address lead paint in your home.
Windows that wont open or close properly because they are no longer square are considered racked. Racking is typically not a problem caused by the window itself it is most often caused by the settling of a house over the course of many decades. Not only will a racked window need to be repaired in order to function properly, racked windows can also lead to a number of additional problems ranging from increased air and moisture infiltration to broken sash joints. The good 11
Unpainted jambs decrease friction and allow window sashes to open and close more easily.
Image Courtesy of Patty Spencer
Example of a window that will not close completely because it is racked
Image Courtesy of geoffcoats.com.
news is that historic windows can usually still be repaired, but you must also determine and address the root cause of the racking, or your repairs will be unsuccessful. Unless the original cause of the racking is addressed, replacing a racked window with a new replacement window will likely lead to the premature failure of the replacement.
Storm Windows and Alternatives to Window Replacement
Storm windows create an extra layer of insulating air between the interior of a home and the weather outside. They also reduce air and noise infiltration. Properly repaired and maintained historic wood windows combined with properly installed storm windows can yield energy savings as good as replacement windows, and typically for a lower cost too. By keeping your original windows intact, you also preserve the historic character of your home. In any case, if your home is designated historic or is located in a National Register Historic District or local Conservation District, you should consult your local jurisdiction before installing storm windows of any kind.
Interior Storm Windows and Thermal Window Inserts Interior storm windows and interior thermal window inserts can provide much of the insulation benefits of window replacement at a lower cost and with dramatically lower impact on the historic character of a home. These products also provide a sizable reduction in the amount of noise that can enter a home through the window area.
Interior thermal window inserts are held in place by compression tubing whereas interior storm windows sometimes require the installation of an interior bracket or frame that remains in place even when the storm window is removed. Interior storm windows and thermal window inserts are frequently made out of acrylic glazing, which is relatively lightweight and strong, making them easy to remove and put back into place. While this is true, they do impact your ability to open or close a window.
In most instances, interior storm windows or interior thermal window inserts will reduce or eliminate condensation that may form on single pane windows in winter. If moisture does build up between the interior storm window and the single pane window one proposed mitigation technique is to drill very small weep holes into the exterior window frame so that moisture can escape. Seek the advice of a storm window professional before undertaking such measures. In this circumstance, having too much weather stripping can actually be detrimental as that can also prevent moisture from escaping the space between the interior storm and exterior windows. 12
Exterior Storm Windows Exterior storm windows have long been a common method for making historic homes more comfortable. Exterior storm windows come in a variety of materials and can be custom built to meet your specific needs. In order to maintain a historic appearance, windows should be designed to reflect the design of the original windows. For example, with double hung windows, your storm window sashes should mimic the location of the meeting rail where the upper and lower sashes come together. This will make the appearance as seamless and unobtrusive as possible. Exterior storm windows can vary in price depending upon the material, but can offer considerable cost savings over entire window replacement.
Insulated Glass Systems (IGS) Another method of improving the energy efficiency of historic windows is the installation of insulated glass into the existing window sashes. The single pane glass is removed from the original sash, along with the original glazing compound. The sash opening is then modified so that insulated glass and new glazing compound can be installed in the opening. Often the installer will perform additional weatherization measures like caulking and weather stripping before installing the insulated glass. The process does alter the original appearance of the windows, albeit slightly, and as with other weatherization measures, you should consult with your local jurisdiction as to whether the installation of insulted glass systems requires historic design review. Some IGS vendors use a holistic approach that includes fully weatherizing your historic windows in addition to adding insulated glass. Even with that amount of work, insulated glass systems can still be far less expensive than entire window replacement.
Other Types of Historic Windows and Their Weatherization Solutions
Casement Windows As mentioned above, most storm windows can be custom built to match your original historic windows. This includes casement style windows that swing out and away from the house when opened. On casement style windows, the type of storm window that is used most often is called a piggy back style because it actually mounts directly to the original sash frame. This allows the window to still be opened although the additional weight may make opening more difficult. In addition to storm windows, you can also install weather stripping in casement windows much the same as you would with double‐hung windows. Make sure that you use compression type weather stripping for casement window applications.
Metal Frame Windows Metal framed windows, typically steel or aluminum, present unique challenges for repair and weatherization that may be best addressed by a window repair professional. If the metal is corroded or bent, the window may have to be removed first in order to be properly cleaned and repaired. You can still install custom storm windows, but adding weatherstripping, especially along sliding surfaces can be difficult. You can (and should) still caulk around metal windows to prevent air infiltration just as you would with other types of windows. The National Park Service provides additional detail for repairing and weatherizing metal windows in their Preservation Brief Number 13, available online. The URL for this brief is located in the resource section of this booklet. In the event that your metal windows are beyond repair, there are companies throughout the United States that produce custom metal windows. 13
Piggy‐Back casement style storm window
Courtesy of Jim Heuer.
Weatherizing Using Window Treatments
Shutters, Curtains, Shades, Blinds, Films, and Awnings There are numerous types of window treatments that have been used historically to lessen drafts or heat/cold transfer around windows. Some of these measures can be very cost effective while producing positive results. Of the following measures, those that are employed in the homes interior will likely not require historic design review. As always, however, check with your local jurisdiction prior to installing anything on the exterior of your home if it is designated historic or located within a historic or conservation district of any kind.
Shutters Interior shutters provide privacy and in the summer shading, but are otherwise mostly for decorative purposes. In the Pacific Northwest exterior shutters are typically only decorative as well and therefore neither historically appropriate nor an effective weatherization measure. In Portlands historic districts, installation of exterior shutters will require Historic Design Review too. However, if your historic home does have original working shutters or you have definitive evidence that the home once had working shutters, they can also be used effectively to keep the sun out of your home in the summer, but remember, they offer little protection against winter drafts.
Curtains Curtains can provide an affordable and historically appropriate solution for improving comfort in a home with historic windows. Depending on their coverage and weight, they can minimize draftiness, and lessen the impact of solar gain (how a home heats up) on a homes interior. Curtains can also be custom fit and styled to maintain an appropriate historic look and feel.
Shades Like curtains, shades can increase interior comfort, while also reducing solar gain. Insulated shades are now readily available and, if properly installed, they can greatly increase the R‐value of your window area, increasing your homes energy efficiency. If historic appearance is desired, shades can also be custom made of fabrics that are period appropriate.
Blinds Blinds are one of the most common window treatments available today. They can be custom fit for historic window openings and can be insulated as well, increasing your homes energy efficiency much the same as insulated shades. Blinds have little or no visual impact on the exterior of a historic home. Some blinds can be raised from both the top and bottom providing light, shade, and privacy as needed.
Films In recent years, films have been developed that can easily be applied by a homeowner to the window panes as a method of reducing the amount of sunlight that enters a home. While these films may deflect some of the light entering a home, there is no conclusive evidence that such films provide any additional weatherization benefits. Therefore they should not be viewed as viable window weatherization measure. 14
Awnings Awnings were commonplace on homes built from the late 19th through the mid‐20th century and therefore if they are made of suitable materials can be considered historically appropriate. Installation of new awnings on historic homes in Portland, however, will require Historic Design Review. Given that they are used to shade the interior of a home from the sun, they are mostly effective in the summertime. They are often retractable too, so in the winter the sun can be allowed to heat the homes interior.
Historically Sensitive Replacement Windows
This guidebook is meant to provide some basic guidelines for the repair, maintenance, and replacement of historic windows. In Portland, if you live in a designated historic home or in a home located within a historic district, a window replacement project will require a Historic Design Review that can be costly and time consuming. Most repairs however, including those involving the replacement of individual window parts (such as a rotted bottom rail), will not require such a review so long as the replacement parts are identical to the original.
The replacement of historic windows should only be considered as a last resort after all other measures of increasing energy efficiency have been addressed in a home. No matter the quality of the replacement window, there may still be air infiltration that if not properly mitigated, will decrease the effectiveness of the replacement window. As mentioned earlier, windows only account for around 10% of the overall energy loss in any home. Many other measures can and should be undertaken prior to replacing original historic windows.
If all other measures prove unsatisfactory or if there are windows that are beyond repair such as those with significant rot then replacement windows may be considered. Even if you think that your windows are physically beyond hope, it is always recommended that you check with a local window repair professional (not a new window salesperson) to see whether or not the windows can be repaired. Repairing your original windows almost always costs less than buying replacements and when combined with proper additional measures, such as storm windows, will produce significant energy savings.
Windows are a character defining feature of any building. If they are replaced by windows of inferior quality, windows made of substitute materials, or windows of a design that differs from the originals, the changes will be obvious and often incompatible. Most off the shelf replacement windows will not be approved for use in a historic district, especially if they change the original style of window such as the conversion of a pair of double hung windows into a single large picture window. Such alterations will diminish the historic qualities of a home. If, after all other home weatherization measures and repairs have taken place, it is determined 15
Early 20th century postcard depicting an awning on a Portland, OR home.
Courtesy of the Architectural Heritage Center.
that a window (or windows) must be replaced, then owners of historic homes should examine their windows carefully to determine what they will need in order to replace them in the most historically sensitive manner.
Most historic windows in the Pacific Northwest are constructed of wood and it is recommended that if windows must be replaced, that they are replaced in‐kind (of same/similar material, style, and dimensions). Substitute materials, especially vinyl, are not appropriate for a historic home. Replacement windows often have different profiles than the original windows and lack key features of original windows such as the ogee lugs that extend from the bottom of the upper sash on the typical double hung windows found in our region. Many historic homes have windows with so‐called divided light sashes, where the sash glass is divided into multiple sections by wooden dividers called muntins. If divided light windows are replaced, the replacements should also have real divided light sashes with muntins that match the originals. The use of windows with faux historic divided light inserts is not acceptable for use in historic homes.
There are numerous materials used in the manufacture of replacement windows. Before proceeding with any window replacement in a historic home, it is recommended that you consult with your local jurisdiction to determine what types of replacement windows may be acceptable. They may also be able to provide you with examples of replacement window types that have been approved for use in other historic homes in your area.
As a general rule the following types of windows should not be considered acceptable replacements for original wood windows in historic homes:
Fiberglass or aluminum clad
Fully fiberglass replacement windows have been approved in Portland for use in historic homes, but are reviewed on a case by case basis.
Adding New Windows Where There Are None
Owners of historic homes should think very carefully about their needs before they consider adding a new window to a home where previously there wasnt one. Such alterations to the home can have a dramatic effect on its historic character and may not be viewed as acceptable by the local jurisdiction and/or historic landmarks review body. In Portland, any addition to a 16
Example of muntins on
a pair of historic wood windows.
Photo courtesy of Patty Spencer
home located in a historic district or individually listed on the National Register of Historic Places, requires Historic Design Review. It is understandable that some homeowners wish to increase the size of their homes through building additions or dormers. In these instances, new windows should be consistent and complimentary to those on the rest of the home in regards to material, style, profile, and proportions. Newly added windows should reflect both the placement of the homes original windows and the ratio of wall to window surface. Removing original windows altogether, especially on the front or prominent sides of a historic home should always be avoided.
Often homeowners wish to update their basements into finished living spaces for their families or to create an accessory dwelling unit (ADU) for a relative or other tenant. In such instances, larger windows are sometimes required as a health and safety matter. In Portland, if larger basement windows are required for an ADU in a designated historic home or a home located in a historic district, the replacement windows are typically allowed provided that 1) The frames are of the same material as other original basement windows and have the same physical profile, 2) The width of the windows matches that of adjacent windows (as long as they also meet safety codes), 3) The surface area of the replacement or new window that is visible from the street or from adjacent properties is no more than is visible of the historic windows being replaced, unless they are on the rear of a house. This usually means that the windows are mostly concealed by window wells. Larger, replacement windows for ADUs that meet safety code for egress, are typically not allowed on the front of contributing resources in Portlands historic districts.
What if the Original Windows Were Already Replaced?
Often the original windows in a historic home were already replaced some years ago. If a homeowner needs to replace such windows, they should first consider what the originals may have looked like and try to find new replacements that are made of historically accurate materials, as well as matching the style, profile, and proportions. One way to determine what the original windows may have looked like is to explore your neighborhood or similar neighborhoods in your area to find houses of a similar period and style with their original windows intact. You can also review old house magazines, books, and websites to find examples of period windows. Once you have determined a window style that is appropriate you can then consult with window manufacturers to determine who makes the type of windows you need.
This guidebook was produced with the support of the Irvington Community Association. Without their leadership this project could have not been completed.
In preparation of this guidebook, several window repair and weatherization experts from the Portland, Oregon area were consulted. Their expertise is reflected in the types of solutions offered in the several issue categories. All experts consulted in the development of this guidebook are listed in the resource portion of the guidebook.
The most recent publications related to window repair and weatherization have also been consulted and are cited in the resource portion of this booklet. This includes publications from the National Park Service, the National Trust for Historic Preservation and other nationally recognized leaders in historic preservation as it relates to windows.
Architectural Heritage Center, Portland, Oregon. Directory of Professional Resources
City of San Francisco, Standards for Window Replacement (City of San Francisco, 2010).
City of Seattle, Do‐it‐yourself Home Energy Audit: A Step by Step Guide for Improving Your Homes Energy Efficiency, (City of Seattle, 2008).
Hensley, Jo Ellen and Antonio Aguilar, Preservation Brief 3: Improving Energy Efficiency in Historic Buildings, (National Park Service, 2011). http://www.nps.gov/hps/tps/briefs/brief03.pdf
Irvington Community Association, Portland, Oregon. http://www.irvingtonpdx.com/
Kinney, Larry and Amy Ellsworth, Center for Resource Conservation, The Effects of Energy Efficiency Treatments on Historic Windows, (CRC, 2011).
Myers, John H., Preservation Brief 9: The Repair of Historic Wooden Windows, (National Park Service, 1981). http://www.nps.gov/hps/tps/briefs/brief09.htm
Park, Sharon C., Preservation Brief 13: The Repair and Thermal Upgrading of Historic Steel Windows, (National Park Service, 1984). http://www.nps.gov/hps/tps/briefs/brief13.htm
National Trust for Historic Preservation, Repair or Replace Old Windows: A Visual Look at the Impacts, (NTHP, 2009) http://www.preservationnation.org/information‐center/sustainable‐communities/weatherization/windows/additional‐resources/nthp_windows_repair_replace.pdf
National Trust for Historic Preservation, Window Types: A Residential Field Guide, (NTHP, 2009).
New York Landmarks Conservancy, Repairing Old and Historic Windows: A Manual for Architects and Homeowners, (Preservation Press, 1992).
Oregon Health Authority. http://cms.oregon.gov/oha/Pages/index.aspx
Portland Bureau of Development Services. http://www.portlandonline.com/bds/
Portland Bureau of Planning and Sustainability. http://www.portlandoregon.gov/bps/39750
Portland Office of Neighborhood Involvement. http://www.portlandonline.com/oni/index.cfm?c=28380
Sedovic, Walter and Jill H. Gotthelf, APT Bulletin: Journal of Preservation Technology, No. 36, Vol. 4 What Replacement Windows Cant Replace: The Real Cost of Removing Historic Windows, 2005.
Synertech Systems Corporation and the City of Boulder, CO, Making Your Historic Building Energy Efficient: Volume One, Principles and Approaches, (Synertech Systems Corporation, 2007). http://www.bouldercolorado.gov/files/PDS/historicpres/hist_supp_vol1_energy_efficient.pdf
U.S. Department of Energy, Energy Saver Tips. http://www1.eere.energy.gov/consumer/tips/m/index.html
U.S. Department of Housing and Urban Development, Lead Paint Safety: A Field Guide for Painting, Maintenance, and Renovation Work, (HUD, 2001). http://public.health.oregon.gov/HealthyEnvironments/HealthyNeighborhoods/HealthyHomes/LeadPoisoning/ParentsFamilies/Documents/LeadGuide_Eng.pdf.
U.S. Department of the Interior, National Park Service, Technical Preservation Services, Documentation Requirements for Proposed Window Replacement. http://www.nps.gov/tps/standards/applying‐rehabilitation/successful‐rehab/windows‐documentation.htm
U.S. Department of the Interior, National Park Service, Technical Preservation Services, Secretary of the Interior's Standards for Rehabilitation and Illustrated Guidelines on Sustainability for Rehabilitating Historic Buildings, (NPS, 2011). 19
Portland, Oregon Area Window Repair and Weatherization Professionals
Chosen Wood Window Maintenance http://www.chosenwwm.com 503.266.3830
East Portland Sash and Carpentry Co. ‐ www.eastportlandsash.com 503.453.6301
Fresh Air Sash Cord Repair www.freshairsash.com 503.284.7693
Indow Windows www.indowwindows.com 503.284.2260
Jack of the Woods www.jackofthewoods.com 503.249.8201
Jeffrey Franz www.windows‐woodwork‐detailing.com 503.234.9641
Oculus Fine Carpentry http://oculuswindow.blogspot.com 503.740.6222
Truax Builders Supply www.truaxnw.com 503.256.4066
Versatile Wood Products www.versatilewoodproducts.com 503.238.6403
Viridian Window Restoration, LLC www.viridianwindow.com 503.922.2202
Well Hung Windows, LLC www.wellhungwindows.com 503.235.2493
Window Menders www.portlandwindowcompany.net 360.562.0772
WHERE TO FIND - Historic District Design Review Fee Schedule
by ICA – October 2011
Click on "fees," then "fee schedule," then "landuse service fee schedule/"
Scroll down to Design Review Fees
How to File a Complaint
by ICA – March 2012
If a possible illegal construction project is observed, neighbors can:
1) go to www.portandmaps.com, type in the address, click on "permits/cases" to see if there is a building permit or another complaint against the structure. If no permit...
2) file a complaint with the City at portlandonline.com/bds, click on "enforcement" and complete the online form -OR- call 503 823-2633 to record a complaint. Note: you must include your name and address although thie will not be given to the owner of the structure in question.
Include the comment "this is a Historic District."
3) contact Dean Gisvold, chair of the ICA Land Use Committee, firstname.lastname@example.org or Barb Christopher, chair of the ICA Historic Preservation Committee, email@example.com
About the Irvington National Register Historic District
by ICA – March 2012
On October 22, 2010, the US Secretary of the Interior added Irvington (all 2,811 structures) to the National Register of Historic Places. This is a high honor!
With this designation, Irvington benefits from protections that encourage preserving the neighborhood character and livability for future generations.
Irvington is a good example of a streetcar suburb, with 94% of its structures built between 1894 and 1948. Irvington is also recognized for its eclectic mix of architectural styles, examples of the work of many of Portland's best architects and builders, and its late 19th century covenants. The neighborhood occupies most of the 1851 Donation Land Claim of Captain William and Elizabeth (Dixon) Irving. The name Irvington first appeared in an 1887 plat map.
The nomination for the National Register designation was funded by the Irvington Community Association.The services of a professional architectural historian were used to oversee the work. During a multi-year process, volunteers collected historical data, identified building characteristics, and took more than 8,000 photographs.
The designation will affect all new construction and most changes to the exterior of primary structures. Secondary structures of less than 200 square feet are exempt.
The district's boundaries run from the middle of NE Fremont south to the middle of NE Broadway; the middle of NE 7th east to NE 27th (both sides of the street). A small portion of NE 28th (between NE Tillamook and NE Hancock) is also included.
Some Benefits of Living in The Irvington Historic District
Historic designation may keep property values from decreasing over time and provide a steady source of interest in home-ownership in the district.
Historic designation provides additional notice and protection from demolition for contributing structures within the boundaries.
Oregon's Special Assessment of Historic Property Program was the nation's first state-level historic preservation tax incentive. It "freezes" a property's assessed value for 10 years. Owning a property in a Historic District does not automatically provide this benefit. For eligibility, process, and application forms see:
Owners of commercial property are eligible to reapply for a second term without needing local government approval.
Variances to the building code may be available to restore or retain a structure's historic integrity.
How Does Living in a Historic District Affect Property Owners?
The City of Portland officially began regulating the Irvington Historic District on November 2, 2010. Because the purpose of these regulations is to preserve Irvington's historic character, all new construction and most exterior alterations are subject to Historic Design Review. To determine if a particular treatment is subject to or exempt from review, refer to the Portland Zoning Code 33.445.320. When a proposal requires review, it must meet the approval criteria in the Portland Zoning Code 33.846.060 G.
If you have questions regarding code interpretation or process, call the Zoning Hotline at 503-823-7526.
Historic Design Review is carried out by the Land Use Division of the Bureau of Development Services (BDS). BDS is a cost-recovery agency so there are fees associated with the review and, because public notification and appeal periods are mandated by state law, the process takes a minimum of six weeks from the date the application is deemed complete. See fees at
The Irvington Community Association web page has relevant information posted at http://www.irvingtonpdx.com/news/historic_district.html
Please note this information is general in nature and not meant to take the place of advice from the BDS staff or design professionals.
Glossary of Terms for Irvington Historic District
Assessed value tax freeze Oregon tax incentive program
Boundaries as established by historical plat maps
Commercial structures other than single family residences
Contributing structures substantially intact as originally constructed
Covenants restrictions to construction and uses 1891-1916
Design review Official City review of proposed external changes to a structure
Period of eligibility structures built between 1894 and 1949
Tax credit Federal tax credit program for commercial use
The Irvington Community Association, through its Land Use and Historic Preservation Committees, may be able to assist property owners with information regarding their home‘¦s history and architecture, and regarding restoration/renovation issues that may arise in connection with the permitting Historic Design Review process.
For more information contact
Barb Christopher firstname.lastname@example.org
(Chair of Historic Preservation Committee) or
Dean Gisvold email@example.com 503-226-7321
(Chair of Land Use Committee)
Prepared by the Historic Preservation Committee of the
Irvington Community Association
HOW TO LEARN IF YOU ARE IN A HISTORIC DISTRICT
by ICA – March 2012
Resources for determining if your house in located in an Historic District
In November 2010, the Irvington neighborhood in Portland became a National Register
Historic District resulting in design review for exterior alterations and for new in-fill structures
Such districts exist throughout the nation. Irvington is the largest National Register Historic District in Oregon, and one of the largest in the country.
o Portland provides a list (http://bit.ly/districtlist) of Historic Landmarks
and a map (http://bit.ly/districtmap) of Historic Landmarks and Districts
is downloadable. The Planning Bureau lists Portlands Historic and
Conservation Districts (http://bit.ly/planningbureau).
Oregon Historic Sites Database Links
o The Oregon Database is searchable by address:
o Oregon Parks & Recreation Dept.: Heritage Programs: National
o Oregons Historic Districts are listed by county:
National Register of Historic Places
o Phone for information specifically on a listed property: 202-354-2262
o One can search by state and/or county and/or city.
o The NRIS is arranged by the historic name of the property. If you
know the address of the property, but not the historic name, you will
have to look at each listing in the county and/or city.
Save Money and Reduce Taxes with the National Register Historic District Designation
by Jim Heuer, Irvington Historic Preservation Committee – March 2012
Much has been made recently about the Historic Design Review process and the associated fees being charged by the City for that review in Irvington and other Historic Districts. And the ICA Committees are working hard on solutions to that issue. But there is another side to the process of remodeling and rehabilitating historic properties in Irvington that has not been mentioned nearly enough: the State and Federal tax incentives designed to encourage investment in historic properties.
With the designation of the Irvington Historic District, all contributing properties over 85% of the buildings in the District are potentially eligible for two important programs that could save you money, depending on your tax situation and your specific plans for the property. Read on to learn more about the potential for your Irvington property
The State of Oregon was one of the pioneers in enacting tax incentives for rehabilitation of historic properties, dating back to 1975, when the Oregon Special Assessment Program was introduced. In the ensuing years, the Legislature has revised the Program several times generally expanding its applicability and reducing burdens for property owners. For example, for many years participation in the Program required the owner to stage an open house for the public once per year. That requirement was eliminated by the Legislature a number of years ago.
All contributing properties in the Irvington District are potentially eligible for the Special Assessment, including single family homes and commercial properties of all types. Prior to creation of the District only individually listed National Register Historic Properties a time consuming and expensive process were eligible. With the District now in place, NO separate listing is required to take advantage of the potentially significant economic benefits of the Program. You can determine if your property is designated as Contributing using the Irvington Historic District map found on the web at http://tinyurl.com/7kalzrb (This is a shortcut we set up to make the complicated City of Portland web address much easier to type in.) Look for your address in the listing below the map, and youll see your propertys designation under Resource Status.
Basically, the Program freezes the assessed value of your property as of the date of application for a period of 10 years. Thus the increase in assessed value triggered by major rehabilitation or expansion of your home will be put off by 10 years while you enjoy the benefits of the investments immediately. Both commercial and residential properties are eligible for two 10-year terms of the benefit providing that for the second term (only) the application must include work addressing improvements in: seismic, energy conservation, ADA, sustainability or a combination of these.
To qualify for the Program you must meet these requirements:
Plan to invest 10% of the Real Market Value (RMV) of the property in the first 5 years on a combination of rehabilitation and maintenance projects, with emphasis on rehabilitation. RMV is as shown on PortlandMaps.com and includes the value of the improvements (that is, the house or building built on the land) NOT the land itself. For example if your total RMV for your property is $445,000, in Irvington your land value will be around $180,000, leaving the improvement value at $265,000 youd need to plan to spend at least $26,500 on your rehabilitation and renovation project to qualify not an unrealistic threshold in todays rehab marketplace.
Submit an application to the State Historic Preservation Office, paying a fee of 1/10th of 1% of the total assessed value. For that $445,000 house, the fee would be $445.
Provide a Preservation Plan which spells out exactly what is proposed to be done and how much it is expected to cost. Typically the plan is something you can prepare yourself without the help of a consultant, but if you already have plans and specifications from an architect or contractor for your proposed rehabilitation project, that may well provide the basis of your plan. You can even include work already done providing that it was completed within two years prior to your application (Note: Just because youve completed the work doesnt mean you arent eligible!)
Show proof of property insurance
What kinds of rehabilitation and renovation are eligible? Interior and exterior rehabilitation and maintenance are all covered not just the primary structure on your lot (i.e. your house) but any historic outbuildings and landscaping/landscape features (think rehabilitation of your original stone or concrete retaining walls). Exterior changes may or may not trigger Historic Design Review. If that is required, you will need to show that you have received approval of the Review if you are including that work as part of your plan. Additions and new construction on your property can be included as long as it has passed Historic Design Review. This latter fact is very important, as projects to expand square footage of your home or commercial building will necessarily trigger a re-assessment for tax purposes, which may not be subject to any Measure-5 limitations, and the Special Assessment Program can put off that day of reckoning for 10 years! And better yet, this tax savings can be passed to buyers if you decide to sell.
For more information, you should check out the SHPO website for application forms, FAQs, and complete application instructions: http://www.oregon.gov/OPRD/HCD/SHPO/tax_assessment.shtml, or contact Susan Haylock, program coordinator at 503-986-0672, email firstname.lastname@example.org, to get your specific questions answered.
Ive found SHPO staff very helpful in providing guidance when we applied for the Special Assessment a number of years ago, and eager to discuss your plans with you. Youll also find on the SHPO website a recent example application for the program, which currently just happens to be for a property here in Irvington.
If you are planning or have recently completed a rehabilitation and/or restoration project on your house that will cost at or above the threshold for the Special Assessment, you should look very carefully at this option. In the case of our home, starting with property taxes in 2001 identical to those of our neighbor, in the last 10 years we have paid a total of $10,000 less in taxes than our neighbors who are not in the Special Assessment Program (as they say your mileage may vary).
The other important tax-saving program your property may be eligible for is the Federal Historic Property Tax Credit program. This program is aimed at Contributing income-producing properties of which there are a great many in Irvington, both rental real estate and commercial/retail properties.
Development and Alterations in a Historic District
by Portland Zoning Code 33.846
Chapter 33.846 Historic Reviews; Section G
On April 24, 2010, The City adopted Chapter 33.846 Historic Reviews. The review procedures in this chapter supersede procedural and threshold statements in the Citys [previously] adopted design guidelines documents for historic districts.
In the place of specific neighborhood Design Review Guidelines for Irvington, the City of Portland adopted Chapter 33.846 HISTORIC REVIEWS which states under 33.846.060.E.1.b:
Historic Districts without district-specific guidelines. Where there are no guidelines that are specific to the Historic District, the criteria in Section 33.846.060.G are the approval criteria
[The delineated criteria in the code are those of the national standard of the U.S. Secretary of the Interior and apply to all listed individual properties and Historic Districts. It is not clear how new construction is to be reviewed.]
G. Other approval criteria. Requests for historic design review will be approved if the review body finds that the applicant has shown that all of the applicable approval criteria are:
1. Historic character. The historic character of the property will be retained and preserved. Removal of Historic materials or alteration of features and spaces that contribute to the propertys historic significance will be avoided.
2. Record of its time. The historic resource will remain a physical record of its time, place, and use. Changes that create a false sense of historic development, such as adding conjectural features or architectural elements from other buildings will be avoide3d.
3. Historic changes. Most properties change over time. These changes that have acquired historic significance will be preserved;
4. Historic features. Generally, deteriorated historic features will be repaired rather than replaced. Where the severity of deterioration requires replacement, the new feature will match the old in design, color, texture, and other visual qualities and, where practical, in materials. Replacement of missing features must be substantiated by documentary, physical, or pictorial evidence;
5. Historic materials. Historic materials will be protected. Chemical or physical treatments, such as sandblasting, that cause damage to historic materials will not be used;
6. Archaeological resources. Significant archaeological resources affected by a proposal will be protected and preserved to the extent practical. When such resources are disturbed, mitigation measures will be undertaken.
7. Differentiate new from old. New additions, exterior alterations, or related new construction will not destroy historical materials that characterize a property. New work will be differentiated from the old.
8. Architectural compatibility. New additions, exterior alterations, or related new construction will be compatible with the resources massing, size, scale and architectural features. When retrofitting or sites to improve accessibility for persons with disabilities, design solutions will not compromise the architectural integrity of the historic resource.
9. Preserve the form and integrity of historic resources. New additions and adjacent or related new construction will be undertaken in such a manner that if removed in the future, the essential form and integrity of the historic resource and its environment would be unimpaired; and
10. Hierarchy of compatibility. Exterior alterations and additions will be designed to be compatible primarily with the original resource, secondarily with adjacent properties, and, finally, if located within a Historic or Conservation District, with the rest of the district. Where practical, compatibility will be pursued on all three levels.
Modifications Considered During Historic Design Review The approval criteria for modifications considered during historic design review are:
A. Better meets historic design review approval criteria. The resulting development will better meet the approval criteria for historic design review than would a design that meets the standard being modified; and
B. Purpose of the standard.
1. The resulting development will meet the purpose of the standard being modified; or
2. The preservation of the character of the historic resource is more important than meeting the purpose of the standard for which a modification has been requested.
33.846.080 Demolition Review
A. Purpose. Demolition review protects resources that have been identified as contributing to the historic significance of a Historic District . Demolition review recognizes that historic resources are irreplaceable assets that preserve our heritage, beautify the city, enhance civic identity, and promote economic vitality.
A. Review procedure. Demolition reviews are processed through a Type IV procedure.
B. Approval criteria. Proposals to demolish a historic resource will be approved if the review body finds that one of the following approval criteria is met.
1. Denial of a demolition permit would effectively deprive the owner of all reasonable economic use of the site; or
2. Demolition of the resource has been evaluated against and, on balance, has been found supportive of the goals and policies of the Comprehensive Plan, and any relevant area plans. The evaluation may consider factors such as:
a. The merits of demolition
b. The merits of development that could replace the demolished resource, either as specifically proposed for the site or as allowed under the existing zoning;
c. The effect demolition of the resources would have on the areas desired character;
d. The effect that redevelopment on the site would have on the areas desired character;
e. The merits of preserving the resource, taking into consideration the purposes described in Subsection A; and
f. Any proposed mitigation for the demolition.
PORTLAND ZONING CODE
33.445.320 Development and Alterations in a Historic District
Building a new structure or altering an existing structure in a Historic District requires historic design review. Historic design review ensures the resources historic value is considered prior to or during the development process.
A. When historic design review is required in a Historic District. Unless exempted by Section 33.445.320.B, below, the following proposals in a Historic District are subject to historic design review:
1. Exterior alteration of a primary structure;
2. Building a new structure;
3. Exterior signs;
4. Nonstandard improvements in the public right-of-way, such as street lights, street furniture, planters, public art, sidewalk and street paving materials, and landscaping, that have not received prior approval of the City Engineer;
5. Proposals using one of the provisions of the a, Alternative Design Density Overlay Zone, specified in Sections 33.405.040 through .080; and
6. Proposals in the Albina Community plan district using the provisions of Section 33.505.220, Parking Requirement Reduction, or Section 33.505.230, Attached Residential Infill on Vacant Lots in R5-Zoned Areas.
B. Exempt from historic design review.
1. Construction of a detached accessory structure with 300 square feet or less of floor area when the accessory structure is at least 40 feet from a front property line;
2. Changes that do not require a building, site, zoning, or sign permit from the City, and that will not alter the exterior material or color of a resource having exterior materials or color specifically listed in the Historic Resource Inventory, Historic Landmark nomination, or National Register nomination as an attribute that contributes to the resource's historic value;
3. Normal repair and maintenance other than change of facade color where exterior material or color is specifically listed in the Historic Resource Inventory, Historic Landmark nomination, or National Register nomination as an attribute that contributes to the resource's historic value;
4. Parking lot landscaping that meets the standards of this Title and does not include a wall or fence;
5. Improvements in the public right-of-way, such as street lights, street furniture, planters, public art, sidewalk and street paving materials, and landscaping, that meet the City Engineers standards;
6. Rooftop mechanical equipment, other than radio frequency transmission facilities, that is added to the roof of an existing building if the building is at least 45 feet tall and the mechanical equipment is set back at least 4 feet for every 1 foot of height of the mechanical equipment, measured from the edges of the roof or top of parapet;
7. Public Art as defined in Chapter 5.74; and
8. Solar panels that are located:
a. On a flat roof, the horizontal portion of a mansard roof, or roofs surrounded by a parapet that is at least 12 inches higher than the highest part of the roof surface. The panels must be mounted flush or on racks, with the panel or rack extending no more than 5 feet above the top of the highest point of the roof. Solar panels must also be screened from the street by:
(1) An existing parapet along the street-facing faηade that is as tall as the tallest part of the solar panel, or
(2) Setting the solar panel back from the roof edges facing the street 4 feet for each foot of solar panel height.
b. On a pitched roof. Panels must be mounted flush, with the plane of the panels parallel with the roof surface, with the panel no more than 12 inches from the surface of the roof at any point, and set back 3 feet from the roof edge and ridgeline. See Figure 218-5. In addition, solar panels may not be on street-facing elevation, or on the front half of any roof surface of an elevation facing within 90 degrees of the street. See Figure 218-6.
9. Eco-roofs installed on existing buildings when the roof is flat or surrounded by a parapet that is at least 12 inches higher than the highest part of the eco-roof surface, and when no other nonexempt exterior improvements subject to historic design review are proposed. Plants must be species that do not characteristically exceed 12-inches in height at mature growth.
10. Permitted Original Art Murals as defined in Title 4 if the mural is proposed on a building that is not identified as contributing to the historic significance of a Historic District.