Wood Window Preservation Article Collection

What Replacement Windows Can’t Replace: The Real Cost of Removing Historic Windows WA LT E R S E D O V I C a n d J I L L H . G O T T H E L F

Sustainability looks even better through a restored window.

For all the brilliance reflected in efforts to preserve historic buildings in the U.S., the issue of replacing windows rather than restoring them remains singularly unresolved. Proponents on both sides of the issue may easily become frustrated by a dearth of useful data, as well as conflicting information, or misinformation, promulgated by manufacturers. Indeed, it often seems that many preservation practitioners and building owners remain in the sway of advertising claiming that the first order of business is to replace old windows. In the context of preservation and sustainability, however, it is well worth reconsidering this approach. Sustainability and Authenticity

Fig. 1. Comparative values of the embodiedenergy levels of common building materials. Note that glass and aluminum (i.e., principal components of many replacement windows) are ranked among the highest levels of embodied energy, while most historic materials tend to possess much lower levels. Courtesy of Ted Kesik, Canadian Architect’s Architectural Science Forum, Perspectives on Sustainability.

In considering alternatives to replacing historic windows, one needs to keep in mind two important elements: sustainability and authenticity. Sustainability (building green) and historic preservation are a natural marriage, so long as one remains mindful that sustainability is not just about energy conservation.1 Preservation and sustainability involve myriad elements that can work in symbiotic and synchronized ways toward a favorable outcome. For example, preservation work is more labor- than material-intensive, which benefits local economies; natural ventilation afforded via operable windows can reduce the size of mechanical equipment, especially of air-conditioning; and salvaging historic materials, such as wood sash, obviates the need to harvest live trees and other natural resources for the manufacture of replacement units. Similarly, retaining and celebrating authenticity is one key element of an exemplary preservation program. No one should take lightly the option of discarding authentic historic materials —

in this case, windows — without fully evaluating the consequences. Once authentic material is lost, it is lost forever. It does not matter how accurate the replacement window, it never reflects the nuances of the original. Taking the Long View

Historic windows possess aesthetic and material attributes that simply cannot be replaced by modern replacement windows. Like preserving whole buildings, restoring historic windows is a solid step forward into the realm of sustainability. The present approach to sustainability, however, still too often focuses on new construction and issues such as “intelligent” windows and energy efficiency, while overlooking other important, holistic benefits of preserving historic windows, such as the following: • Conservation of embodied energy (i.e., the sum total of the energy required to extract raw materials, manufacture, transport, and install building products). Preserving historic windows not only conserves their embodied energy, it also eliminates the need to spend energy on replacement windows. Aluminum and vinyl — the materials used in many replacement windows — and new glass itself possess levels of embodied energy that are among the highest of most building materials (Fig. 1).2 • Reduction of environmental costs. Reusing historic windows reduces environmental costs by eliminating the need for removal and disposal of existing units, as well as manufacture and transportation of new units. Also, many replacement units are manufactured with such materials as

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Fig. 2. Many excellent worksheets are available for calculating payback of replacement windows; this one is produced by the Missouri Department of Natural Resources. Results of payback calculations often reveal grossly overstated claims. Courtesy of the Missouri Department of Natural Resources.

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vinyl and PVC, whose production is known to produce toxic by-products. So, while energy savings is green, the vehicle toward its achievement — in this case, replacement windows — is likely to be the antithesis of green.3 • Economic benefits. Restoration projects are nearly twice as labor-intensive as new construction, meaning more dollars spent go to people, not materials. This type of spending, in turn, has the beneficial effect of producing stronger, more dynamic local economies.4 • Ease of maintenance. “Maintenancefree” is a convenient marketing slogan; many replacement windows, in reality, cannot be maintained well or conserved. Vinyl, fiberglass, sealants, desiccants, and coating systems all degrade, and they are materials that remain difficult or impossible to recycle or conserve.5 • Long-term performance. While manufacturers’ warranties have been lengthened in the past few years (they are now generally from 2 to 10 years), they still pale in comparison to the actual performance life exhibited in historic windows, which can reach 60 to 100 years and more, often with just minimal maintenance. Clearly, sustainability takes into account more than just the cost of energy savings. It also promotes salient social, economic, and environmental benefits, along with craftsmanship, aesthetics, and the cultural significance of historic fabric. Still, the issue of energy savings is often used to justify replacement over restoration, but just how valid is this argument? Energy Savings

If the foremost goal for replacing historic windows is energy savings, beware of “facts” presented: they very likely will be — intentionally or not — skewed, misinformed, or outright fallacious. Window manufacturers universally boast about low U-values (the measure of the rate of heat loss through a material or assembly; a U-value is the reciprocal of an R-value, which is the measure of resistance to heat gain or loss). For example, U-values are often misleadingly quoted as the value for the entire window unit, when in fact it is

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the value through the center of the glass (the location of the best U-value), not that of the sash nor the average of the entire unit.6 To be sure that data are being presented appropriately, request the U-values published by the National Fenestration Rating Council (NFRC), which rate whole-window performance.7 When U-values are offered for the entire window assembly, they often are significantly worse (i.e., higher) due to infiltration around the frame and rough opening.8 In cases where replacements tend to warp and bow over time (and they do), this factor becomes ever more crucial.9 It is also important to watch for comparative analyses: some replacement-window manufacturers compare their window units to an “equivalent” single-pane aluminum window. Clearly, this is an inappropriate analogy since these types of windows are not likely to be found in a preservation context.

Payback

Infiltration of Outside Air

Heat Loss/Heat Gain

Infiltration of outside air — rather than heat lost through the glass — is the principal culprit affecting energy; it can account for as much as 50 percent of the total heat loss of a building.10 When retrofit windows are installed over or within the existing window frame, the argument for preservation already exists: restoring the integrity of the fit between the frame and building wall should be the first component of a preservation approach. Sash pockets, pulleys, and meeting rails are areas prone to air infiltration in double-hung units. Yet, several weatherproofing systems for existing windows can overcome these heat-sapping short circuits.11 Replacement-window manufacturers themselves admit that even among replacements, double-hung units present the greatest challenges for controlling heat loss because infiltration occurs most frequently at sash-to-sash and sash-to-frame interfaces, which are highly dependent on the quality of the installation.12 The energy efficiency of restored windows incorporating retrofit components (weatherstripping and weatherseals combining pile, brush, bulb, or “Z” spring seals) can meet and even exceed the efficiency of replacement units.13 This approach is suggested as the first alternative among greenbuilding advocates.14

Heat loss is often discussed, but what about heat gain? In summer, heat gain can add significantly to the energy costs associated with cooling a building.17 Long waveforms within the daylight spectrum that enter through the glass must be able to exit, or else they degrade to heat that then must be overcome by the building’s cooling system.18 Low-emittance (“low-e” or “soft lowe”) glass handles this task best, improving thermal performance by virtually eliminating infrared (long-wave) radiation through the window.19 It accomplishes this task by allowing short-wave radiation through and reflecting longwave heat back to its source, while at the same time providing an appearance that is virtually clear.20 Low-e glazing can be substituted into existing units that are only single-glazed and still achieve important energy savings. Single-pane low-e glass can provide a virtually equivalent level of combined energy savings as a standard new double-glazed unit when used in concert with an existing single-paned sash (e.g., as a storm or interior sash).21 Replacing panes of glass, then tightening up the sash and frame, is a very simple and cost-effective way to achieve the desired whole-assembly U-value without having to modify visible light, mullions, or sash weights.22

Focusing on windows as the principal source of heat transfer may lead to the conclusion that windows are more important than, say, insulating the attic, foundation, or walls. While data vary somewhat, up to 25 percent of heat may be lost through doors and windows.15 But when the aforementioned potential 50 percent loss through infiltration is taken into account, the total effective percentage of heat loss attributed to the window units themselves would be only 12.5 percent. That is a relatively small percentage for a potentially large investment, especially when other options are available. In actuality, typical window-replacement systems offer payback periods that are often nowhere near manufacturers’ claims: the payback of a typical unit could take as long as 100 years (Fig. 2).16

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same results in IG units through the use of applied films (as opposed to an integral layer within the glass) has been shown to greatly reduce the life of double-glazed units by inhibiting the movement of their seals.28 Performance and Material Quality

Fig. 3. At left is a drawing of a typical late-nineteenth- to early-twentieth-century six-over-six, doublehung window. At right is a modern “equivalent” replacement. The considerably thicker mullions and frame of the replacement unit (necessitated by the use of insulated glass) result in a nearly 15 percent reduction of visible light and views. Drawing by Walter Sedovic Architects.

Insulated Glass

Replacement windows nearly always incorporate insulated glass (IG) units. The effectiveness of an IG unit is greatly dependent on the depth of the airspace between inner and outer panes, as well as on the nature, type, and amount of desiccant and seals employed around the unit perimeter.23 While manufacturing techniques for IG units have continued to improve, when IG units fail, they are difficult and time-consuming to replace.24 The additional weight and thickness of IG units preclude their use as retrofits in historic sashes of either wood or metal. Indeed, to compensate for their heft, virtually all IG replacement window mullions, sash, and frames are bulkier than their historic counterparts. The result is that visible daylight levels are reduced by 15 percent or more and views are interrupted.25 Reducing daylight and negatively affecting views are explicitly not consistent with a sustainable approach (Fig. 3).

though, that a U-value is not the only criterion that determines the relative thermal efficiency of a window. Solar and light transmittance also affect performance, and they may be benefit when low-e laminated glass is selected.27 The benefits of laminated glass, though, go much further when considered part of a comprehensive program to restore and thermally upgrade historic sash: • Laminated glass offers significantly higher levels of noise abatement than IG. • Historic glass may be laminated, offering energy and noise benefits while maintaining an authentic finish. • Laminated glass is far easier and less expensive to procure and install and allows for field cutting. •

It offers superior safety and security features.

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Laminated glass may be equipped with low-e glazing to help offset heat gain.

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Historic sash, both metal and wood, can be outfitted with laminated glass without modifying or replacing mullions and frame elements (something that would be required by the installation of significantly thicker IG units).

Laminated Glass as an Alternative

Laminated glass remains an oftenoverlooked alternative to IG units, perhaps because of the industry’s focus on marketing it as “safety” glass. While laminated glass cannot compete with technologically advanced, complex IG units, it does offer enhanced U-values for monolithic glass without having to materially alter the mullions of the historic sash into which it is being fitted.26 It is important to recognize,

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Condensation is reduced as a result of the internal thermal break of laminated glass. A variety of features (UV protection, polarization, translucency, etc.) can be incorporated as layers within laminated glass. Efforts to achieve the

A hallmark of sustainability is longterm performance. Intrinsic within that premise are issues about material quality, assembly, and conservability. As noted above, some material choices (e.g., PVC) incorporated into replacement-window units are inherently not able to be conserved.29 When the material degrades, it then becomes necessary to replace the replacement.30 One of the great virtues of historic windows is the quality of the wood with which they were constructed. Historic windows incorporate both hardwoods and softwoods that were often harvested from unfertilized early-growth stock. Such wood has a denser, more naturally occurring grain structure than what is generally available today from secondgrowth stock or fertilized tree farms. Also, historically, greater concern was given to milling methods, such as quarter- or radial sawing. The resulting window performs with greater stability than its modern counterpart. This alone has far-reaching benefits, from minimizing dimensional change, to holding a paint coating, to securing mechanical fasteners. No amount of today’s staples, glue, finger-splices, and heat welds can match the performance of traditional joinery.31 Similar comparisons could be made of the quality of hardware employed in replacement windows, such as springloaded balances and plastic locking hardware; they cannot compete with the lasting performance and durability of such historic elements as pulley systems and cast-metal hardware. Ease of Maintenance

For cleaning windows, traditional single- and double-hung windows are often outfitted with interior sash stops that may be removed readily, allowing for full access to the interior and exterior, as well as to the pulley system. Both casement and pivot windows are inherently very easy to clean inside and out.

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Replacement windows incorporating tilt-in sash — a feature that on its surface appears enticing — require that there is no interior stop, increasing the potential for air infiltration around the sash. Compressible jamb liners that allow for the tilt-in feature are often constructed of open-cell foams that, once they begin to degrade, lose both their compressibility and sash-to-frame infiltration buffer. The ability to readily disassemble historic wood windows also allows for selectively restoring, upgrading, and adapting individual components of a window throughout its life. Most replacement-window systems cannot make that claim. Aesthetics and Authenticity

Nuances in molding profiles, shadow, line, and color of windows, along with quality and appearance of the glass, contribute greatly to the overall building aesthetic and generally emulate the stylistic details of the building as a whole. Even what might seem like small changes in these elements can and does have a noticeable and usually detrimental effect on many historic facades. Outfitting historic buildings with modern replacement windows can and often does result in a mechanical, contrived, or uniformly sterile appearance. Worse, when historic windows are replaced, authenticity is lost forever. Value and Cost

Repairs of historic windows should add to the value of the property, as an authentically restored automobile would command greater value than one “restored” with plastic replacement parts. While there is a dearth of cost-comparative analyses between a replacement window and its restored, authentic counterpart, empirical knowledge based on field experience covering a wide variety of window types suggests that restoration is on a par, cost-wise, with a middle-of-the-road replacement. Corollary conclusions are that: • cheap replacement windows will always exist to superficially counter the cost-basis argument for restoration; and

high-quality equivalent replacement units have been shown in practice to cost as much as three times that of restoration. Windows are a critical element of sustainability, but sustainability is not just about energy. It is about making environmentally responsible choices regarding historic windows that take into account the spectrum of associated costs and effects. The choice of whether to replace or restore requires embracing a more encompassing definition of sustainability. The answer is not as simplistic as some would have us believe. •

WALTER SEDOVIC, the principal and CEO of Walter Sedovic Architects, works in historic preservation and sustainable design. His work and firm are recognized for integrating greenbuilding approaches and ideologies into preservation projects. JILL H. GOTTHELF is an associate at Walter Sedovic Architects, providing project management, design, and construction administration. She has extensive experience in integrating sustainable building technologies into preservation projects.

Notes 1. Walter Sedovic, “History’s Green Genes” (Greenbuild 2003, The 2nd International Conference on Sustainability, U.S. Green Building Council, Pittsburgh, Pa., November 12-14, 2003). 2. Ted Kesik, “Embodied Energy Comparative Values,” Canadian Architect, Architectural Science Forum, Perspectives on Sustainability, January 2002, http://www.canadianarchitect. com/asf/perspectives_sustainibility/measures_of _sustainablity/measures_of_sustainablity_embodied.htm (accessed November 1, 2005). 3. “Windows,” Global Green USA, Public Housing Authority Toolbox, http://www.global green.org/pha-energytoolbox/tech_windows. htm (accessed November 1, 2005). 4. Don Rypkema, “The Economics of Preservation” (keynote address, Preservation 360°, Saratoga Springs Preservation Foundation, Saratoga Springs, N.Y., March 18, 2005). 5. Paul Fisette, “Understanding Energy-Efficient Windows,” Fine Homebuilding 114 (1998): 68–73. 6. Ibid. 7. National Fenestration Rating Council, http:// www.nfrc.org. 8. Andrew M. Shapiro and Brad James, “Creating Windows of Energy-Saving Opportunity,” Home Energy 14, no. 5 (1997). 9. Fisette, 68–73.

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10. Ibid. 11. Shapiro and James. 12. Bill Mattinson, Ross DePaola, and Dariush Arasteh, “What Should I Do About My Windows?” Home Energy 19, no. 4 (2002). 13. The growing market for retrofit seals has resulted in an ever-increasing supply of highquality weatherstripping products manufactured in a variety of materials and configurations for application in both typical and nontypical applications. 14. Shapiro and James. 15. Hastings Borough Council, “Have You Got Money to Burn?” http://www.hastings.gov.uk/ energy_efficiency/heat_every_home.aspx#money _to_burn (accessed November 1, 2005). 16. Shapiro and James. 17. Fisette, 68–73. 18. Ibid. 19. The National Energy Foundation, “Energy Advice: Saving Energy: Insulation,” http:// www.nef.org.uk/energyadvice/insulation.htm (accessed September 16, 2005). A. Roos and J. Karlsson, “Performance Criteria for Coated Glazings in Windows,” in Proceedings from Glass Processing Days, Tampere, Finland, 653–656 (Uppsala, Sweden: Dept. of Material Science, Angstrom Laboratory, Uppsala University, 2001). See also http://www.glassfiles.com/ library/23/article440.htm (accessed November 1, 2005). 20. Roos and Karlsson, 653-656. 21. Mattinson, DePaola, and Arasteh. 22. Shapiro and James. 23. “Product Information: Insulating Glass,” PPG Industries, Inc., http://www.ppg.com/gls_ residential/share/res_ins.htm (accessed November 1, 2005). 24. James Piper, “Windows: Repair or Replace?” Building Operating Management (Jan. 2004). 25. Chad Randl, Preservation Tech Notes, Windows, No. 19, Repairing Steel Casement Windows (Washington, D.C.: U.S. Department of the Interior, National Park Service, Cultural Resources, 2002). 26. California Glass Bending Corporation, “Static-Exchange Correlation-Polarization (SECP) Tables,” http://www.calglassbending. com/secptabl.htm (accessed November 1, 2005). 27. Roos and Karlsson, 653–656. 28. James Piper, “Avoiding Common Window and Window Film Mistakes,” Building Operating Management (Oct. 2004). 29. Fisette, 68–73. 30. John M. Corbett, “A Last Look at Historic Wood Windows,” Traditional Building 14, no. 6 (2001). 31. Fisette, 68–73.

SEVEN TO SAVE ENDANGERED PROPERTIES LIST, 2006: Original & Historic Wood Windows: Repair and Preservation PROJECT CO-SPONSORS: HISTORIC ALBANY FOUNDATION, INC. & ASSOCIATION FOR PRESERVATION TECHNOLOGY, NORTHEAST CHAPTER. The Preservation League of New York State designated Original & Historic Wood Windows as one of the listing for the “Seven to Save Endangered Properties Program” of 2006. Each year thousands of historic wood windows are removed and sent to landfills across New York State. Along with project partners Historic Albany Foundation and the Association for Preservation Technology-Northeast Chapter, the League has been particularly concerned about this issue because original wood windows are such an important part of the appearance and character of a historic home. Property owners should have all of the facts before they opt for replacement. What’s all the fuss about windows? You might think that windows mainly serve as functional components of a building to provide light, ventilation and a view outside. Of course, they also impact the overall appearance of the building—just consider the effect of unpainted windows on an otherwise attractive building. And that may be why you are thinking about sprucing up the exterior of your property with new windows. You have many options for improving the looks and function

of your historic wood windows. I’m just changing the windows and keeping the rest of the house the same. While often seen as interchangeable parts, windows are actually one of the most important aspects of a building’s original material fabric and historic appearance. The design of the windows is just as important as any other decorative element. Windows offer clues to the age of the house, demonstrate the styles or construction techniques of a region or period, reflect later changes to the building, and can be exceptional examples of craftsmanship or design. Since they are original design elements which relate to other parts of the architectural style, overall scale and proportion of a building, we say that the windows are an important part of a building’s character. By considering the changes in window design brought about by changes in technology and in design ideas, we can construct a timeline of window types that help us identify the original style of a house or the period during which it was updated. In the United States, the earliest windows were casement (hinged windows opening out like a door), and buildings retaining such windows were likely constructed during the

earliest period of European settlement. In later revival styles they were installed to imitate the historic period. An examination of the materials themselves would help determine the age and date of the windows in each case. As double-hung windows (with top and bottom sash) became more common in the eighteenth century, glass technology improved to produce larger panes of glass. The earliest sash commonly contained anywhere from 6 to more than 16 individual panes (also called “lights”). As the nineteenth century progressed, the industry was able to make larger panes until only two panes were used per sash or even a single pane sash became more common. At the end of the nineteenth century, as revival styles came into vogue, multiple-light and patterned sash became the norm, solely for aesthetic reasons, as technology allowed for virtually unlimited pane size. There were also stained glass windows available and affordable even for middle class homes. In addition to the number and size of panes, the shape of the window also changed over time. Certain window types are essential parts of architectural styles. But my windows are old and junky. In the case of wood windows, old does not necessarily mean

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Seven to Save Endangered Properties 2006: Repair and Preservation of Wood Windows

obsolete or lower quality. In fact, given the quality of materials and craftsmanship involved in the original fabrication of your windows, they may be better than anything being made today. Windows built before the 1950s were likely constructed of milled heartwood or old-growth wood which is more dense than the woods now available. Older windows will nearly always far outlast their replacements if properly restored. In addition, traditional joinery such as pegged mortise and tenon joints used in older windows have proven to be more durable through changes in climate and moisture than are glued finger joints. If just one part of an old wood window fails, it is easier to repair than a component in a modern window. The wood window sash can be removed from the window openings, the problem piece can be repaired and the sash reinstalled in good working order. With a modern window unit, a broken pane of glass usually requires the installation of an entirely new insulated glass unit which is not easily removed from the wood, aluminum or vinyl window members. Typically the cost for repairing the glass alone is close to the amount of a new replacement window. When I do finally get my windows to open, I can’t get them to stay in place. I’d rather have new, working windows. Many a stubborn window can be repaired by simply replacing a cord which is broken or painted so that it no longer rolls easily along the pulley. This allows it to properly use the counter weight which not only aids in moving the window but also in keeps it in place. If you are replacing the weights, make sure that they are the right size—neither too heavy

or too light—to function properly with your windows. If the cords are not the culprits, you may need to remove paint from the window or frame itself which is causing the window to stick. I don’t think there are any repairs that I can do myself. This is the true benefit of old wood windows – they were built to be reparable. Most homeowners have the skills needed to repair old wood windows, whether the problem is a broken sash cord preventing the window from moving up and down easily or staying in place, or there is a broken pane of glass. Old window sash can be easily removed from the window openings, paint and glazing putty that has built-up can be stripped and renewed, a broken pane can be swapped out for a new pane (reglazing), the cord holding the weight can be replaced and reattached and window put back in place. No engineering degree is necessary, and all the tools and materials needed are available at your local hardware store. Replacing the glazing putty, the glass, the sash cords, and the weather-stripping can be done at a cost equal or less than $1/linear foot. There are countless step-bystep instructions available in books or on the Internet to guide a homeowner in making these repairs. Don’t be overwhelmed by trying to do all the windows at once. Try to assess which windows need which type(s) of repair and break the project down into phases. Begin with the more simple repairs. Find out whether a workshop is available in your region. I barely know a hammer from a handsaw, and I don’t know of any contractors who repair windows.

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A local hardware store can easily replace a broken pane of glass within a sash (reglazing). Most contractors can do simple repairs to wood elements or reglazing. (Others may try to sell homeowners on replacement windows, where most of the markup is in the product, not the labor.) For larger projects, property owners can contact a local historic preservation organization which might maintain a list of contractors who work on historic buildings. Homeowners can also reach out to their municipality or state preservation office for contractor lists. When interviewing a contractor it is important to ask for and check references. It is also a good idea to get several contractor estimates to compare. What one person says is irreparable may be another person’s idea of a simple repair. I live in an historic district and am not allowed to install storms or screens over my windows. I don’t want to have to mess with installing and removing storm windows. Many buildings dating to the late19th and 20th century added protection during the winter by using wooden storm windows in the North and shutters or blinds in the South. Therefore, it is absolutely historically appropriate to install wood storms over your wood windows. In fact, this added layer will protect the paint and glazing of your primary window and eliminate any drafts the weather-stripping has not stopped. Most homeowners associate wood storms with the obligation of having to install them in the fall and remove them in the spring. This was often the case in the past,

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Seven to Save Endangered Properties 2006: Repair and Preservation of Wood Windows

when homeowners would take that opportunity to wash the windows and touch up any failing paint. Today there are many manufacturers of traditionallooking wood storm windows that incorporate screen panels which eliminate the need to swap the storms for screens each year. My contractor just shook his head and told me it would be cheaper to replace all the windows. It is rare that all windows on a single building fail at the same time, and the most cost effective approach to windows is to repair and maintain individual windows as they need work. By definition, repair work is most often done on site by local workers and is limited to only the work needed for each individual window: One window may need only new or reset hardware while another more deteriorated needs an entire new bottom sash. One advantage of repair is that it can be easily phased to spread the work and costs over a time period, as permitted by weather and budget. One efficient way to carry out needed maintenance may be to combine the work with an exterior painting project. This will most likely require coordination between the painter and window repair specialist. Because wood has the advantage of being repairable with readily available materials and tools, a program of repairing windows to a like-new condition, followed by periodic maintenance, is the most cost efficient long term solution. Stop and think—if only one or a few windows are in bad shape, repairing them is easier than replacing all windows in the whole house. I was told I’d be better off with all new windows that would help me battle high heating bills.

Many property owners think they must replace their old wood windows in order to save energy. Studies have indicated that in most cases [15 to] 20% of heat loss in a building is through the windows. The remaining 80% is through walls, roofs, floors and chimneys. Following this model, reducing the heat loss through windows by 50% will only result in will only result in a 10% decrease in the overall heat loss in the building. Replacement windows can be built using wood, vinyl, or aluminum sash, and may have single, double, or even triple glazing. It is this capacity for double or triple glazing which is thought to be more energy efficient. However, most heat loss from a window occurs from air infiltration between the sash and the window frame. Homeowners will gain better energy efficiency by maintaining the caulk around a window and using a properlyfitting storm window (R factor 1.79), than with a double-paned replacement window (R factor 1.72). To put it a different way, according to the American Society of Heating, Refrigeration and Airconditioning Engineers (ASHRAE), an historic wood window with storm transfers LESS heat per square foot of material (known as U-value), than replacement windows on vinyl tracks with either a double-glazed wood sash or a double-glazed metal sash. Replacement windows can contribute to heat loss due to the spring-loaded vinyl track along the frame. As previously stated, most air loss occurs in the space between the sash and the frame. Wood is a far superior insulating material than vinyl, particularly the dense, old-growth wood found in historic houses. New window installation, no matter what the material used for the sash,

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requires vinyl tracks to hold the sash and allow it to move up and down. Vinyl, which contains vinyl chloride, classified by the EPA as a Group A, human carcinogen, expands and contracts in heat and cold, and will deteriorate with sun exposure more rapidly than wood. Because vinyl window tracks are naturally exposed to heat, cold and sun, they will degrade and eventually lose their air seal. When this happens, they must be completely replaced. Historic wood windows, which run along wood tracks with the help of counter weights, can be maintained. If the wood finally deteriorates, it can be easily repaired or replaced without having to replace the entire window. In many instances, therefore, the vinyl windows do not deliver energy savings nor last as “permanent” windows. I was told that my historic windows aren’t up to code. Code requirements for windows are generally applied only when rehabilitation or construction projects are undertaken. Oneand two-family residences are governed by the Residential Code of New York State which regulates various aspects. Sections: a) Energy Conservation. Historic buildings are exempt from the energy conservation requirements of the code, per Section 1101.2.5.3. The code’s definition of historic buildings includes those determined significant by the state or local governing body, and those listed in or determined eligible for the National Register of Historic Places. For existing (non-historic) buildings, Section 1101.1.3 of Chapter 11 identifies buildings and conditions that need not comply with the chapter’s energy provisions, including when less than 50% of the building’s

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Seven to Save Endangered Properties 2006: Repair and Preservation of Wood Windows

windows are not being altered. b) Light and Ventilation (Section 310.1). When windows or rooms are changed or substantially altered, windows are required to provide a minimum amount of light and ventilation for basements and habitable rooms. For light, habitable rooms must be provided with aggregate glazing area of not less than 8 percent of the floor area of that room. For ventilation, the minimum operable area is calculated as 4 percent of a room’s floor area, a total of the amount provided by windows, doors, louvers or other approved openings. c) Emergency Egress. Windows may also be required for emergency egress purposes. Section 310.1 requires one emergency escape opening for basements with habitable space and every sleeping room. These must have a sill height of not more than 44” above the floor, and a minimum net clear opening of 5.7 square feet (5.0 square feet for grade floor openings): minimum dimensions are 24” in height and 20” in width. I know there is lead paint on my windows and I’ve heard that they are not safe. While eliminating lead paint on windows may be required for projects funded by the U.S. Department of Housing and Urban Development (HUD), no such requirements exist for New York State homeowners undertaking work at their own houses. Lead dust can create critical health issues, especially for children, however the presence of a stable lead surface is acceptable. The key is to keep finishes in good condition, repair and repaint on a regular cycle, and avoid stripping paint unless there is evidence of real paint failure. When stripping is determined to

be necessary, the procedures outlined in the National Park Service’s publication Preservation Brief #37 Appropriate Methods for Reducing Lead-Paint Hazards in Historic Housing will provide excellent guidance. Among the most important recommendations for dealing with lead paint: (1) children should live elsewhere while the work is being done (2) all existing paint need not be removed-only that required to provide a sound surface for repainting (3) it is important to use appropriate protective gear which can be found at a hardware store (4) clean up after every work session.

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American Precision Museum, 2005; 802674-5781; www.americanprecision.com Articles What Replacement Windows Can’t Replace: The Real Cost of Removing Historic Windows, Walter Sedovic & Jill Gotthelf, Association for Preservation Technology (APT) Bulletin, 36:4, 2005. “What Should I do about my Windows?” by Bill Mattinson, Ross DePaola, Dariush Arasteh, Home Energy, July/Aug 2002, p. 24-31. “Wood Windows: A Guide to Repair and Replacement” by Richard Spigelmyer, Traditional Building, Jan/Feb 1997, p. 35, 44. Websites: Secretary of Interior's Standards for Rehabilitation. Detailed guidelines on the accepted practices for various approaches to preservation work, see www.cr.nps.gov/local-law/arch_stnds_0.htm.

Note that wet sanding can minimize dust. Chemical strippers can present problems. In addition to the potential health concerns associated with working with chemicals, the pores of wood wet from the chemical reaction can open up and permit lead based paint to seep into the wood. You can find the Preservation Brief on the National Park Service website at: www.cr.nps.gov/hps/tps/briefs/ brief37.htm, or visit www.cr.nps.gov/buildings.htm, then go to “Preservation Briefs” No. 37.

www.historichomeworks.com Includes many restoration topics including windows.

Resources

www.apti.org/chapters/northeast/index.cfm

Books and Booklets The Repair of Historic Wooden Windows, John H. Myers, National Park Service Preservation Brief #9. Online version in Preservation Briefs section at

Contributors: Kimberly Konrad Alvarez, Landmark Consulting ◘ Erin Tobin Bearden, Director of Preservation Services, Historic Albany Foundation ◘ Marilyn Kaplan, Principal, Preservation Architecture ◘ Tony Opalka, Historic Preservationist and Architectural Historian ◘ Lorraine E. Weiss, Program Manager, Technical and Grant Programs, Preservation League of New York State

www.cr.nps.gov/buildings.htm or order at 866-512-1800. Repairing Old and Historic Windows, New York Landmarks Conservancy, 1992; www.nylandmarks.org/; 212.995.5260

www.windowrepair.com/ “A website devoted to the fine art of making old windows work like new and be energy efficient too.” The Old House Journal has all types of information about preservation issues, restoration, history and products: www.oldhousejournal.com/index.shtml (Not to be confused with “This Old House”) www.oldhouseweb.com/ Has a section on step-by-step window repair. Project Co-sponsors: Historic Albany Foundation: www.historic-albany.org Association for Preservation Technology: www.apti.org/, APT Northeast Chapter:

Save Your Wood Windows, John C. Leeke, www.historichomeworks.com/hhw/office/c onsult.htm; 207 773-2306; Windows on Preservation, John C. Leeke, William McCarthy & Ann Lawless,

PRESERVATION LEAGUE OF NEW YORK STATE ● 44 CENTRAL AVENUE, ALBANY, NY 12206 518-462-5658 ● [email protected] ● www.preservenys.org