NAHB Research Center has been studying builder buying trends since the 1970s, but that information has remained largely in-house, shared (commercially) with only a few dozen manufacturers each year.

(See Charts Below)

This year, we asked the NAHB Research Center to compile some key data from its annual Builder Practices Survey--specifically for use in BUILDER magazine. We selected some of the results, broken down by construction category from the ground up, that we feel offer a snapshot of changes taking place in the products and techniques of U.S. home building.

These shifts are not always happy ones for builders. Some are code-mandated. Others happen in response to price increases. And even the sexiest new innovation can lead to trouble if new products aren't fully integrated with old materials. So, for better and worse, here's a five-year snapshot of how your product usage has changed.

Foundations: Slab Happy

While full basements still prevail, their popularity has dropped several points in recent years. Contributing to that change has been the triple threat of mold, unstable soils (building on less desirable sites), and stricter energy codes emphasizing below-grade insulation. But along with the bad news has come some relief--including International Residential Code acceptance of shallow frost-protected foundations.

Still, according to Mark Laliberte, a building industry coach and consultant with Shelter Source in Lakeville, Minn., the move toward slab-on-grade is a mixed blessing. It's less resource intensive (fewer yards of concrete and displaced soils), but leaves a tough design challenge--what to do with mechanical systems.

"For 40 years we've had HVAC in the basement and a lot of houses with moldy basements. It makes perfect sense to try to optimize another area of the house--but a lot of builders end up putting a five-ton air conditioner into a 250-degree attic," he says. "That's a phenomenal inefficiency."

Wood Framing: Rise of the Machines?

Statistics about wood framing, which accounts for the structure of about 85 percent of new homes, show that factory-built components are finally making their move, replacing site-built stick framing. Not all growth is in the factory, however. Note that custom categories--such as post and beam and log homes--also increased in popularity, offering a clear sign that the second-home market is strong.

Engineered Lumber: More in the Floor

Flip open BUILDER and look at any show home, and you may get the impression that every stick of dimensional lumber is being replaced with engineered I-joists and glulams. But the survey shows this perception is somewhat skewed. Solid-sawn lumber retains its place as market leader, for both headers and floor systems. That lead is slipping, however, especially in floor framing, and that lost market share appears to be headed toward laminated veneer lumber (LVL), glulams, and the latest rising star--open web joists. This product, virtually unknown in 1998, had gained 4 percent of the floor framing market by 2001.

Windows: Fall and Rise of Wood

The precipitous decline in the use of unclad wood windows in recent years looked bad for the wood window industry. Polyvinyl chloride (vinyl) windows appeared ready to take over the world. Inspired by Andersen's decades-old clad systems, wood window makers went proactive and offered builders (and buyers) the same features they found appealing in vinyl windows--low maintenance, ease of installation--but with the added bonus of a wood interior to frame out with normal carpentry skills.

What's more, some firms actually trumped vinyl by offering aluminum cladding, which allows for a wider color gamut than vinyl--which is sensitive to heat and ultraviolet light.

PVC windows, of course, now dominate the fenestration universe. They have seized much of the low-cost niche served by aluminum, due in part to stricter energy codes.

"We're almost forced to use vinyl out here, thanks to Title 24 [California's energy code requirements]," notes Greg Costanzo, director of construction for Syncon Homes in Roseville, Calif.

That doesn't mean vinyl windows have improved every builder's satisfaction, however. Costanzo notes that vinyl frames have created big problems for his firm, because it finishes homes with stucco. When windows expand and contract, gaps often occur between the frame and the stucco.

"We've got a new system now where we use this Dow 1199 (sealant)," Costanzo notes. "Then we use a Tyvek window wrap. Then we seal every jamb [with a rubberized membrane]. We have to do that on every window, and it takes a lot of time."

Another surprise: Vinyl now leads the market in high-end homes, where wood was once the darling. But where do composites such as Andersen's Renewal or Marvin's Integrity line fit in? They were just hitting their stride when this survey was completed--so stay tuned in coming issues for more up-to-date information about the coming composite revolution.

Doors: Outer Utility, Inner Beauty

As reduced maintenance rises on homeowner priority lists, builder purchase patterns for exterior doors have closely paralleled those of windows. The traditional painted wooden door is losing constituents at about the same pace that aluminum and vinyl-clad wood are ratcheting up production. There's something about plastics ... .

At the same time, both aluminum and steel-framed doors, once an industry standard, especially for secondary entrances, have lost some ground.

A more surprising shift has taken place with interior doors. Many builders have pulled away from the hollow-core wood doors to offer solid-wood panel doors. One explanation: Huge increases in home prices in recent years have forced builders to reconsider products that offer the perception of greater value--we often hear builders say that buyers like hearing the "thud" of a solid-wood door--and vinyl and composite door manufacturers are now beefing up their products to compete on that level.

Siding: Vinyl's New Nemesis

Perhaps more than any new product category, fiber-cement siding has deeply penetrated its entrenched competitors. But this product is not really new. Only the marketing, the attention to appearance, and the emphasis on making installation easier for builders is new. Australia-based James Hardie, the forerunner in this category in the United States, has been making these cementitious composite products since PVC was still a sticky glob in a test tube.

"I think fiber cement came into its own when the cost became reasonable as an alternative to vinyl," notes Mark Laliberte of Shelter Source. "It's a very good product but it has to be applied right. I see people putting fiber cement directly over OSB, with no housewrap. That's a mistake. Fiber cement can absorb water, so you need to pan flash windows and get the water to drain off the building."

Insulation: An Internal Affair?

Hand-in-glove with stick framing, fiberglass insulation continues to dominate the industry. An entire sub-industry of fiberglass installers has grown up around the product, so it's a position that's hard to unseat. Products such as blown cellulose and spray-in foams have taken small bites out of the market share, but not enough to scare the big firms into radical change.

One positive sign, according to Laliberte, is the increasing use of blown-in products (of all types) for walls, instead of traditional batts. "I bet that we see a 30 percent loss overall, nationally, in performance due to sloppy batt installation," Laliberte contends. "I'd like to see a lot more use of products like Optima (CertainTeed), and other blown-in products. Those installers tend to be thermal professionals, and they're doing the job with care."

Roofing: Up with Quality

Asphalt roofing still tops the majority of new homes, but architectural-grade products have become far more prevalent. Use of these premium materials has grown by more than 9 percent over the past five years. This shift is attributed in part to production of larger, more luxurious homes, which tend to showcase roof elevations.

Also of note, as clay tile gained slightly in market share, concrete and fiber-cement roofing lost ground, perhaps in response to negative reports issued to the National Roofing Contractors Association about the performance of certain cellulose-fiber reinforced roofing products. Fiber-cement roofing served admirably for many years--back when it was made with asbestos fibers--but some manufacturers have had trouble matching that performance after replacing the asbestos with cellulose.

HVAC Systems: Passing on Gas

Manufacturers of gas heating equipment took a pounding in recent years, as geopolitical changes took a torch to one of their essential selling points: low cost. Prices suddenly increased fourfold, and many builders turned to electric systems. Wood as a primary heating resource continued to drop off, as oil and electric prices remained relatively stable during most of the period. If the decline in the number of clean-burning gas units is bad news for the environment, the overall increase in the number of high-efficiency (and super high-efficiency) units (both gas and oil) softens the blow.

"We're seeing a lot more closed combustion units," notes Laliberte, "and the benefits are very high. No backdrafting and a better built product. Now if we can just get builders to stop putting them in the garage, where they suck in gases that shorten the life of the unit."

Decks: Changing the Guard

Even before copper chromium arsenic (CCA), pressure-treated wood began to be phased out of residential use last year, builders were looking toward alternatives for use in decks and porches. Presumably, CCA use in porches refers to posts in contact with the ground, where many builders still rely on CCA products. The biggest news, of course, is the fast-growing acceptance of wood/plastic composites. These materials, often made with high-recycled content, have plenty of promise, if a short pedigree.

"The colors are more stable," notes Laliberte. "They're not ugly like they were at first. I'd also say these composites could be our best choice environmentally--if only they can figure out a way to recycle at the end of their useful life and keep them in extended use."

Wanted: More Testing

With increased prosperity and widespread use of new materials comes increased need for life-cycle testing.

We know from experience how long a wood window lasts. But does anyone really know how long the latest vinyl version will hang tough before it becomes brittle or bent? That's a question we all need to ask the new captains of industry in the building product stream. Companies who make products such as PVC siding and doors now have the capital (and the longevity) to undertake serious life-cycle testing on products. They can also use this flush moment to clean up their environmental records.

For example, to date, few virgin PVC products such as windows and siding are recycled. Most vinyl siding instead ends up in landfills, despite its high initial cost to the environment. Will we finally see widespread support of regional recycling centers by the PVC industry? As the builder, you have the right to ask hard questions about durability, energy efficiency, and environmental impact. Let manufacturers know you expect them to use your goodwill (and good money) toward more research and environmental efforts.

Gathering the Data To obtain meaningful data for the BUILDER Practices Survey, the NAHB Research Center collected information from about 2,800 builders, who built around 60,000 homes annually. The responses shown in the charts refer to per-house averages for 50 states. For example, a score of 38 percent for fiberglass batts would mean that 38 percent of the homes the respondents built in the given year included that product.

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