By Kim Arnott
While still a very niche market in Canada, concrete homes are finding increasing acceptance among buyers seeking energy efficiency, noise reduction and durability.
However, those aren't the benefits London, Ont., builder Paul Rawlings touts when selling homes built with insulating concrete forms (ICFs). He simply points to the comfort.
"Walk into a home with an ICF basement, and it's a totally different feel than a regular basement," he says. "There's no dampness or cold. You notice it right away. We sell it from the point of view that you get better and more usable space."
Since building his first ICF home in 1995, Rawlings has become such a fan of the technology that he includes ICF foundations as a standard feature in all of his custom homes.
While a variety of ICF systems are available on the market, the basic concept is to create an insulated concrete wall by joining a series of hollow, lightweight blocks of expanded polystyrene connected by plastic or steel webs that are then reinforced with steel and filled with concrete. The result is a concrete wall sandwiched between two layers of high-insulating foam. The system can be used for both basements and above-grade walls, with an overall cost increase of about five to eight percent over building a traditional wood-frame home.
Over the last 20 years, the ICF system has increased in popularity, says Ross Monsour, director of marketing for the Ready Mixed Concrete Association of Ontario.
"Energy efficiency is one of the big drivers," he says, noting that an ICF system creates a sealed R-20 to R-23 wall that provides an excellent air barrier. Along with fewer air leaks than a wood-frame wall, the mass of concrete used in an ICF wall slows down the passage of heated or cooled air through it. Estimates suggest that homes with ICF exterior walls require 44% less energy to heat and 32% less energy to cool than comparable frame houses.
Due to the air-tightness of the ICF walls, they are also considerably better than wood-frame for reducing noise and drafts, says Rawlings, who has seen a demand for them in rural settings, where homeowners don't have the benefit of nearby buildings to cut down on wind, as well as for cottages and homes alongside lakes or noisy roadways.
While there is a learning curve involved in working with the concrete forms, Rawlings says it isn't difficult for builders to learn the new processes involved in the construction of an ICF home. One of the most important elements is pre-planning. Locations of hydro and gas services, furnace, hot water and other venting, exterior water taps and central vacuum lines need to be established early in construction, prior to pouring the concrete. "You have to involve the trades right from the very beginning," says Rawlings. "With the ICF, we're forced to be more proactive and plan ahead."
Monsour notes that there are other benefits to builders working with the ICF technology. The lightweight forms are easy for crews to handle, the foam can easily accommodate electrical wiring and less after-market service is required because there is no settling, or nail pops with the concrete. The system also allows exterior walls to be completed more quickly, enclosing a home to allow building to continue even during poor weather conditions.
"It's something that used to be seen as sort of exotic," says Don Johnston, senior director of technology and policy with the Canadian Home Builders Association. "But now there's a whole set of builders who are committed to it."