drscott | Retrofitting windows

Back when I owned the house at 77-79 College Avenue in Somerville, many of my projects were intended to save heating costs. We had converted the boiler to gas from oil, installed new storm windows, and insulated a few places; then I made custom covers for the leaded windows using Lexan, a wonderful GE polycarbonate that is much stronger and lasts longer than plexiglass -- it's used in most lenses for glasses, for example. That was 25 years ago, and when I visited the place again last year, the Lexan looked pretty much unworn.

We're replacing most of the windows and sliding glass doors in our Eichler starting Dec. 1st. The giant sliding glass door in the third bathroom (floor to ceiling, wall to wall) would have cost about $2800 to replace; but since it's made with translucent glass and isn't often used, I tried to figure out a way of retrofitting it instead of replacing. I hit on a solution of putting new panes of Thermoclear, which is a dual-wall cellular Lexan, directly on the old glass on the outside, silicone caulking the edges. The Thermoclear (actually the knockoff I could get at TAP Plastics) cost about $200, but the result looks good and will be almost as efficient as the new door would have been. Here's a picture of the stuff: