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Window Restoration
by Dr. Oneida Cramer

Before replacing those drafty old windows with new aluminum windows or thermal panes, homeowners should consider the merits of restoration, according to Tom Clark of Leeds-Clark. For their work on window restorations, Leeds-Clark received the Craft Award at the Third Annual Preservation Dallas Achievement Awards, held last week.

?Aesthetically, there?s no comparison between a true divided light wood window and an aluminum window that has one of those little fake grid systems to make it look like there are six panes of glass, ? Clark said. Homes built before the early 1960?s typically had wood or steel framed windows. Although aluminum was introduced in the late 1930?s, it was a rather expensive material used on only a few homes until growing popularity and cheaper prices put aluminum windows on about every home built since mid 1960?s.

While energy efficiency is often blamed for ripping out old windows, in nine out of ten cases, improper maintenance made the windows regress to where they?re not performing properly.

?So many coats of paint have been applied, that the window could not close properly?seat all the way down against the sill?and would allow air to come in around it,? Clark said. Then people would run caulk all the way around on the inside and outside perimeter adding further to the unattractiveness of the window. Also, when a piece of glass might get broken, instead of putty, glazing, and retouching the paint or re-painting the window, people would just caulk the glass with caulking or silicone.

Because of the dramatic swing in Texas temperatures and humidity, a good paint job lasts an average of seven years before cracking and peeling appear, regardless of the brand of paint or length of the warranty, according to Clark. ?The warranty on a paint job covers material only; materials are only a fraction of labor costs.? And painters would rather have customers come back to them after seven years because, even with discounts, repainting sells more paint and labor. However, repainting over multiple layers of paint may last only a couple years before cracking and flaking begin. So remove all old paint after about three coats to avoid this problem.

?People look at aluminum windows for less maintenance, over a long period of time,? Clark said. ?But we find the same things wear out on aluminum windows, and then these windows don?t operate like they originally did.? What?s more, wood framing makes a better insulator than aluminum framing, energy-wise.

?When it comes to wood, there is no comparison to the wood in old structures,? Clark said. It came from older trees when they were felled. So, the graining is a lot tighter, and the wood doesn?t absorb water like the wood produced out of today?s fast growing trees. This wood is OK if protected inside walls. But if exposed to the weather, the lumber deteriorates rapidly. To compensate, window companies now use metal clad or vinyl cladding on the outside of windows. Cladding cuts down on paint maintenance, they say. But an underlying factor is that good quality wood is getting harder and harder to find.

Retrofitting an old window with weather stripping and removing all the years of paint to make the window operate efficiently is an easy process.

?We make it historically accurate,? Clark said. ?If there are any replacement components or if new window sashes have to be built, we stay with the exact same profile. Then we rework the weight system to make sure the window opens and closes properly and add weather stripping to make sure there won?t be any air infiltration.?

?Realistically it?s only in the (replacement) glass that you are improving the window?thermally,? Clark said. ?Thermal glass helps control temperature. Where direct sunlight shines on a piece of thermal glass, it will heat up the outer piece of glass (annealed glass); but the dead space between the outer piece of glass and the inside piece of glass (low-e glass) stays significantly cooler.? So, the room gains less heat from the sunlight.

?You can achieve the same affect with window treatments such as blinds or shades that prevent the heat from the direct sunlight from coming in,? Clark said. In fact, a single pane of glass in conjunction with good weather stripping and window dressing actually can reduce homeowner utility costs.

Some people like to have a sunroom, without shades, where the window allows light to come in all the time. In this situation, single pane, tinted glass helps cut down on the interior heat gain, according to Clark. Another solution is to retrofit the window with small thermal panes, which requires routing out?deepening the glass channel?so that the window frame accommodates a thicker piece of glass. Routing out changes the interior wood profile and is a compromise to keeping an exact historical restoration. But the window still retains much of the divided light character.

The biggest disadvantage to having thermal pane windows is the high cost of replacement glass because almost all thermal panes eventually lose their vacuum seal, according to Clark, who has seen panes default anywhere from 2 to 20 years old. And once the seal is broken, condensation builds up giving the window a hazy or cloudy appearance. There is no way to clean these windows; so, homeowners must replace them.

A federal government survey mapped out the dividing line separating areas that benefit from thermal pane windows and those areas that do not according to extremes in low temperatures, according to Clark. That line runs through Waco putting Dallas somewhere in a border area. Sure enough, winters can sometimes be cold, and thermal panes can provide some energy savings although the added benefit of having argon gas inside the thermal panes is unnecessary, according to Clark. In fact, using the low-e glass as a single pane window can provide sufficient insulation for this area.

?Low-e was designed to help keep radiant heat in your home,? Clark said. ?People have a misconception that low-e glass helps cut down on ultra-violet (UV), and that?s not true.? The only way to cut down on UV is through a double pane.

?If you were to have low-e in one window and clear glass in another window close to it, you can tell the difference,? Clark said. ?And the one thing you don?t do is to create a patch quilt effect in your window.? But you can put low-e in all the frames because low-e glass comes in different shading coefficients, some not much different from clear glass.

But, before tossing out your old windowpanes, consider that they might be antique.

?Pre-turn of the century homes, all the way up to the mid 1920?s, have the likelihood of having antique glass,? Clark said. Old cylinder glass with wavy imperfections is worth $10 and $15 a square foot compared to today?s clear (annealed) glass at $3 a square foot glass. First manufactured in the 1930?s, annealed glass is not considered antique, and old annealed glass is quite replaceable.

-by Dr. Oneida Cramer
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