Understand What's Going On Behind Your Walls, Floors and Ceilings.
By Glen Salas for the PATH Partners
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Of all the comforts of home, surely one of the most important is physical comfort: a home that’s not too cool or too warm, not stuffy or drafty or hard to heat. If we think of interior décor
and furnishings as the “software” of the comfortable home, then the “hardware” is the bones of the home itself: the walls, windows, roof and foundation–or what building
professionals call “the building envelope.”
And therein lies the number one homebuyer purchasing mistake: buying high-end comfort “software” installed on shoddy “hardware.” In other words, you can’t know if
you’re really buying comfort until you take a hard look at those bones.
But you don’t have to be an engineer to figure out if a home is built for livability. You only need to understand a few basics about how a home works.
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The Best Kept Secret About Homes
Although two houses in a development can appear identical from the outside, the indoor air quality can be strikingly different–even if the homes have the same heating and cooling systems. Why?
Here’s a little known fact with big implications: a house is an integrated system–not just a collection of products and parts. And like any system, a change in one part of the building
envelope can have a dramatic effect on the whole.
The following tour will help you see beyond kitchen cabinets and indoor surfaces to the building envelope components. The building envelope, after all, keeps the outside out–and a house is
only as good as its first line of defense against the elements.
At each stop along the way, you’ll find tips on what to look for and some important questions to ask your builder. Don’t be satisfied if the builder responds, “We always build
to code.” Building codes dictate the lowest acceptable building standards.
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. If you do, 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. Remember, all building codes require double glazing.
ASK YOUR 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
Although invisible once the house is finished, the foundation is as important to the livability of your house as the walls and ceilings. The worst homeowner headaches often come from below–typically
because of moisture, but also because of pests.
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.
If you have a chance, give the foundation and slab a quick once-over to check the quality of air sealing. Do you see cracks or spaces where the slab meets the foundation wall? You shouldn’t.
Moisture and termites can get into the house through the tiniest openings. There shouldn’t be any translucent areas in the outside waterproofing, either.
ASK YOUR BUILDER:
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? That’s why
it’s critical that builders take the time to be very thorough with air sealing.
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. Tell the builder if you
see any cracks.
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 YOUR BUILDER:
- How will you seal the walls and ceilings of the house?
- How will you make the home tight and still maintain good air quality (with fresh air)?
Insulation
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 Rvalue, with a higher R-value indicating greater thickness and better insulation. Since most heat will escape through the ceiling (hot air rises, remember?) 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. There should be no gaps in the insulation. Special care should be taken to insulate hard-to-reach places, such as wall corners
and around electrical outlets and switches.
ASK YOUR 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 codes require?
Ultimately, a home’s comfort is its most important quality. Buying
a home almost always means making compromises along the way, but the soundness of the building envelope is one area where there should be no room for compromise. Understanding the effects of a home’s
exterior components on comfort and quality–and insisting that your home make the grade–is job one for the savvy homebuyer.
Glen Salas is a senior engineer with the energy and environmental consulting firm D&R International in Silver Spring, Maryland.
