Link to the Home page Link to the Home page
Information ForAboutToolsResourcesTech PracticesNewsroomSearch


 Buying A Home
 Homeowners Main Page

Building Technology 101

Don't talk to your builder until you've taken our home tour:

The Outside Walls
Windows, Doors and Skylights
The Foundation
Walls and Ceilings

The Outside Walls

Let's take them apart. The siding that gives a home its curb appeal may be vinyl, brick, wood, concrete or many other materials. In conventional construction, you'll find "sheathing," or exterior wall board behind the siding. And behind that is an insulated support system-typically wood framing stuffed with insulation, though alternative systems such as steel framing and prefabricated panels are becoming increasingly popular.

Whatever the outside wall is made of, it should be well sealed and well insulated (more on sealing and insulating later). If you're fortunate enough to tour your home during construction, you may have the chance to inspect the walls yourself. "Studs"-the boards or metal forms that make up the framing system-should be straight, with no significant cracks or twists, and no breaks. The sheathing should fit together tightly. From the outside you shouldn't see spaces where sheathing comes together. From the inside, before the insulation is added, you should not see cracks where sunlight pours in. Point them out to your builder.

Windows, Doors, and Skylights

The good news about windows and skylights: they bring light, warmth and beauty into homes and give a feeling of openness and space to living areas. The bad news: they can also let in the cold in the winter and heat in the summer. Buying the right windows, doors and skylights will probably cost a little more, but don't compromise on these upgrades. They'll keep the temperature in your home more comfortable, prevent drafts and block outdoor noise better. They'll also protect against sun damage to your carpet, wood floors, furniture, fabrics and artwork. And even better: they can substantially reduce your monthly heating and cooling bills.

The best way to ensure that you are getting the right windows, doors, and skylights is by asking for ENERGY STAR® qualified products. These products meet strict energy efficiency guidelines set by the U.S. Environmental Protection Agency and U.S. Department of Energy. The alternative: less expensive windows that only pass code-and you'll find yourself avoiding the drafty window seat in the winter, seeing nothing but your blinds in the summer, and paying more on your energy bills year round. Don't let a builder off the hook if he says that the windows will be double-glazed. All building codes require double glazing.

Ask the Builder:
Are my windows, doors and skylights ENERGY STAR?If not, how much more will I pay for ENERGY STAR?Do you normally caulk and weatherstrip all windows, exterior doors and other house penetrations?

The Foundation

The foundation is usually made of cement blocks or concrete. If you have a basement, the foundation walls double as the outside walls of the basement, and a concrete "slab" is poured to form the basement floor. Sometimes, even if you do not have a basement, a slab is poured and the house is built directly on top of the slab. Either way, the outside of the foundation must be waterproofed (it will look like thick paint has been applied). Otherwise, the concrete, which is porous, will soak up moisture, which may lead to mold and other problems.

The best way to insulate the basement on a new home is by using rigid insulation on the outside. If insulation is applied only on the inside walls, dampness-and mold-will likely build up between the walls and the insulation. Also, many basement walls are damp anyway, or become damp during periods of high rainfall. This dampness will often cause moisture and mold problems if it is isolated behind inside insulation. Insulation on the outside of the basement will add to the comfort of the space in a second way: it may actually reduce the inherent dampness of a basement wall because it provides another layer of sealing, and less condensation will occur on the inside wall.

The same applies to a house that is built on a concrete slab. Surprisingly, just by insulating the outside edge of the slab, you can reduce heating bills by 10 to 20 percent and keep your floor warmer than it would be otherwise.

Ask the Builder:
How will you waterproof the basement?
How do you seal the joint between the basement floor and foundation walls?
Will you insulate my basement walls/foundation slab?
With rigid insulation? If not, won't moisture be a problem?
How will you protect the above-ground insulation from damage and from termites? (The builder may either use a termite-resistant insulation, or some other termite barrier.)

Walls and Ceilings

Did you know that air leaks in a home can be responsible for as much as 30 percent of heating and cooling costs-and also contribute to moisture, noise, dust and pest problems? Proper air sealing can prevent these problems, but it takes time.

Air leaks usually occur at wall intersections, where the walls meet the ceiling, and around doors, windows and other outside penetrations such as plumbing and electrical. Before interior molding is added, and before the inside walls are finished and painted, look for cracks or openings in these areas. A crack can mean a drafty corner, or a mold problem in the making.

Another benefit of a tight home: builders can install smaller heating, ventilation and air-conditioning (HVAC) systems-up to 40 or 50 percent smaller, in some cases. That means you save both in the lower purchase price of these systems, and in your monthly energy bills.

Ask the Builder:
How will you seal the walls and ceilings of the house?

If the builder tells you that a home needs to breathe and will get stuffy if it's too tight, tell the builder what both the Energy and Environmental Building Association (EEBA) and DOE's Building America program say: Make it tight and ventilate it right.


No matter how well sealed the walls are, and no matter how good the heating and cooling system is, expect drafts and uneven temperatures if the insulation is inadequate.

Insulation is rated according to its R-value, with a higher R-value indicating greater thickness and better insulation. Since most heat will escape through the ceiling the ceiling should be the most heavily insulated area: from as low as R-13 in the warmest U.S. climates to as high as R-60 in the coldest areas. Recommended wall insulation varies from R-11 to R-21, and floor insulation from R-11 to R-30.

All varieties of commonly used insulation work well when used properly. Be sure to check for gaps in the insulation. Do not skip over the hard-to-reach places, such as wall corners and around electrical outlets and switches.

Ask the Builder:
What R-value insulation will you use on my walls?
What R-value insulation will you use on my ceiling? first floor?
What insulation levels do the building code require?

Content updated on 5/28/2004

Link to PATH Tech Set information Link to PATH Partner Program information Link to PATH Concept Home information
Home | Search | ToolBase | Contact Us | Privacy Policy

Text-Only Version