The Building Envelope - Walls, Attic, Basement, Doors and Windows

Before buying a new heating or cooling system, it makes sense to tighten up your house first. The following steps will reduce your heating and cooling load, improve your comfort, and maybe even allow you to purchase a smaller-and less expensive-furnace or air conditioner when the time comes to replace your existing system.

*If you are replacing your roof, find out how to reduce energy with "cool" roofing materials.

Upgrade Inefficient Windows and Doors

About one-third of the home's total heat loss usually occurs through windows and doors. If your existing windows have rotted or damaged wood, cracked glass, missing putty, poorly fitting sashes, or locks that don't work, you may be better off replacing them. If your windows are generally in good shape, it will probably be more cost-effective to boost their efficiency with inexpensive products purchased from your local building supply or hardware store.

1. The quickest and cheapest option is to seal all window edges and cracks with rope caulk.

2. Another solution is to weatherstrip windows and doors with a special lining that is inserted between the window and the frame. For doors, weatherstrip around the whole perimeter to ensure a tight seal when closed. Install quality door sweeps on the bottom of the doors if they aren't already in place.

3. If you plan to stay in the house for more than a few years, install storm windows. These come as plastic films you affix to the existing window, or a removable and operatable piece of glass that inserts behind the existing window.

4. Finally, prevent radiative heat gain and loss in the summer and winter by installing insulating curtains or drapes on the interior.

Replace Old Windows

Whether replacing windows in an older house or choosing windows for a new house, your decisions on what type of windows to buy will be among the most important decisions you will make in terms of energy use. Because of the impact windows have on both heat loss and heat gain, proper selection of products can be confusing. To get the most up-to-date information on what to look for in energy-efficient windows for your home, visit the Efficient Windows Collaborative.

Basic Features to Look for in a New Window:

Selecting New Windows for Your Home

Windows, doors, and skylights qualifying for the ENERGY STAR label must meet requirements tailored for the country's four broad climate regions: Northern, North-central, Southcentral, and Southern. ENERGY STAR windows must carry the National Fenestration Rating Council (NFRC) label, allowing comparisons of ENERGY STAR-qualified products on specific performance characteristics.

Find and Seal Air Leaks

Hidden air leaks cause some of the largest heat losses in older homes. Common air leakage sites include:

The best material for sealing these hidden air leaks depends on the size of the gaps and where they are located. Caulk is best for cracks and gaps less than about 1/4" wide.

Expanding foam sealant is an excellent material to use for sealing larger cracks and holes that are protected from sunlight and moisture. Today's products are safe for atmospheric ozone. Backer rod or crack filler is a flexible foam material, usually round in cross-section (1/4" to 1" in diameter), and sold in long coils. Use it for sealing large cracks and to provide a backing in very deep cracks that are to be sealed with caulk.

Use rigid foam insulation for sealing very large openings such as plumbing chases and attic hatch covers. Fiberglass insulation can also be used for sealing large holes, but it will work better if wrapped in plastic or stuffed in plastic bags, because air can leak through exposed fiberglass. Specialized materials such as metal flashing and high-temperature silicone sealants may be required for sealing around chimneys and flue pipes. Check with your building inspector or fire marshal if unsure about fire-safe details in these locations.


Insulation is your primary defense against heat loss through the house envelope. However, putting insulation into a house after it is built can be pretty difficult. If there isn't any insulation, the best option is to bring in an insulation contractor to blow cellulose or fiberglass into the walls.

If you have a crawl space, it should be sealed, not ventilated. To do this, use 6-mm thick polyethylene sheeting as a moisture barrier to cover the ground and seal tightly to walls and columns. Then use rigid foam to insulate the foundation walls. In the South, it is important to keep an uninsulated band for inspection of possible termite tunnels.

Information provided by ACEEE (

For more information contact GMG Construction Inc. today at to receive your free consultation and quote.

If for any reason the Cutting Edge Windows should not work with your project, GMG Construction Inc. can offer a variety of other window and door replacement options and services to help. We can get discounted pricing on many different products from various window and door manufacturers. We have a real desire to understand your needs and offer quality advice and the expertise to develop a project that is right for you. There is full warranty on all of our work and we install to manufacturer's specifications. For information contact GMG Construction Inc. today at or (206)779-5609 for your free consultation and quote.