How to Insulate Architectural Windows

The term "architectural windows" has to do with well-designed and crafted windows, which may be either antique or modern in style. These shouldn't come with any built-in draft problems, so you shouldn't need to insulate them with the plastic sheet and hair blow-dryer technique. The most important consideration is the use of expanding spray polyurethane foam, commonly called SPF, as applied around the window frames. This is a common state-of-the-art technique, as of October 2010, but requires extra care for architectural windows.

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  Double-hung windows require extra caution. stacked windows image by Jeffrey Sinnock from Fotolia.com

  Read the instructions and specifications of your windows to see if and how polyurethane foam insulation may be used. Classic style double-hung windows, for example, will likely have spring mechanisms and/or sash pockets and, as a result, the use of polyurethane foam may be restricted. Verify that the window guarantee doesn't require foam installation by certified professional contractors and verify at the local municipal center there are no local code restrictions on the use of SPF.

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  Buy the correct foam and application tools in kit form, complete with containers of SPF, a hose and a spray gun. SPF comes in two main varieties; open-cell foam and closed-cell foam. Buy closed-cell foam for exterior window applications because it is more water-resistant.

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  Protect finished windows from wet foam contact. old wooden church window image by aleksey kashin from Fotolia.com

  Cover finished window and frame edges with removable protective tape to shield from wet foam. Read the instructions and precautions carefully on the SPF products before beginning. The ideal temperature for application is from 75 to 85 degrees Fahrenheit. Keep in mind, however, that windows should be opened or another means of adequate ventilation should be provided to reduce the level of harmful fumes.

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  Put on protective clothes, gloves, goggles and an appropriate respirator mask before beginning work, according to the Spray Polyurethane Foam Alliance. Because of the harmful fumes, a respirator mask with organic vapor cartridges should be used. Lay protective drop cloths and set up a ladder before starting.

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  Spray a continuous foam bead into the cavity between the edge of the new window's frame and the opening the window has been installed into, while standing 18 to 24 inches away from the wall. Begin at the bottom of the window and work from the bottom up on either side of the window and over the top. The foam will expand to two to three times the original size of the dispensed bead and will cure in 45 minutes to an hour.

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  Cut away excess hardened, dry foam that sticks out beyond the desired wall surface using a suitably long, sharp knife. Make sure you use a dust mask to avoid inhaling the toxic dust from the foam, as the key ingredient, isocyanates, can cause health problems when inhaled in dust form, according to the U.S. Environmental Protection Agency, or EPA. Remove all of the dust before the space is reoccupied. Use a putty knife to add spackle over the dry foam as soon as possible.