Fast Cast: For the structure of the new ResRec Center at North Central College in Naperville, Ill., which combines a student dormitory with a campus recreation center, local contractor Glenn Behnke of Mustang Construction turned to precast concrete. "It gave us the ability to put up the shell relatively fast and allow the finish crews to start work on completed sections while we moved to the next section," he says.
Credit: Peter Hoffman
It’s a myth that home building hasn’t changed in a hundred years. Sure, most new homes are still stick-built. But look more closely and you’ll find many incremental, and in some cases wholesale, evolutions in basic products and practices that have improved productivity and performance while reducing costs and cycle time.
Taken together, these advances add up to a sea change in how new homes are built. Think of the proliferation of panel products; insulation products created for every nook and cranny; plated roof trusses, wall panels, and other factory-built, snap-together framing components; and today’s far-superior windows and doors that plug what used to be a critical energy leak.
This is just a small sample of the innovations since the mid-20th century that have entered mainstream practice. Their adoption accelerated during the last decade thanks to economic challenges and environmental objectives. Now many builders have seized on technological improvements to set their homes apart from resales and create more margin opportunity in the new economy.
The innovations profiled here are not necessarily new. But they haven’t received wide-spread adoption either. Most are time-tested with solid track records of predictable performance and cost. They can reduce labor and operating costs, distinguish the performance and comfort of your homes, and inspire more interest among buyers. They are worth close examination.
Block Believer: Bob Cenk, vice president of operations for Homecrete Homes in Stuart, Fla., has built exclusively with ICFs since 2004. "I believe this is the way we should be building all homes, and not just in this market." Between 2006 and 2008, the market share for ICFs as an above-grade wall system more than doubled, if only to about 1.7% of all new homes.
Credit: Josh Ritchie
As minimum standards for the performance of a home’s thermal envelope continue to rise (at least for homes to qualify under Energy Star or other green guidelines), the use of next-generation concrete systems for walls, floors, and roof structures is poised for growth.
The most obvious (and currently most popular) of these alternatives is insulating concrete forms (ICFs). ICF manufacturers basically combine a handful of wall assembly materialsthey mold expanded polystyrene into interlocking CMU-like blocks or into flat panelsto create site-assembled concrete formwork.
ICF users balance the premium cost of the blocks or panels with faster cycle times. Labor savings may also result because the system relieves subs, with varying skill levels, from trying to cobble together a comparable thermal shell out of advanced stick-framing methods and various insulating, flashing, and air-sealing components.
With ICFs, the result, at minimum, is an R-20-plus wall that is permanently insulated on both sides with a thermal mass (solid concrete) core. The blocks and panels also feature integral nailing strips for attaching interior and exterior finishes and the ability to “let-in” mechanical runs, such as wiring and plumbing, without cutting into the concrete core (wall penetrations should be accommodated before the pour).
A similar technology, if less popular than ICFs, is precast concrete panels for below- and above-grade walls as well as floors and roofs. These panels are typically fabricated in a factory, with connecting rebar stub-ups, door and window openings, and service penetrations made per detailed shop drawings. An integral layer of foam insulation boosts thermal mass.
Precast panels have a proven track record and popularity in the non-residential and multifamily realms, which may help the technology transition into single-family housing construction. They also benefit from their more popular use as a below-grade basement wall system, and from the increasing familiarity among builders who use wood-based panelization to help reduce labor costs and cycle time.
Like their foam-form brethren, precast concrete panels require builders to plan and design to a much higher level of detail than they are used to with stick-framing. They must also come to terms with a different labor pool, local building code resistance (despite allowances in the I-codes), and availability issues caused by a specializedsupply chain of regional manufacturers hampered by shipping restrictions.
For all these reasons, precast has struggled to find a sweet spot in single-family. “If your details are very complex, or you’re just building one home, [your] project is not a good candidate for precast,” says Brian Bock, vice president of sales & marketing for Dukane Precast in Naperville, Ill. “If you are building 10 homes on the same block, it makes more sense.”