Building a home that makes as much energy as it consumes requires extreme attention to detail and a willingness to do everything possible to minimize the building's power requirements for heating, cooling, hot water, and lighting. But some things just make more sense than others. “Of all of the things we did to make this home net-zero energy,” says Beverly Stevenart, co-owner, Craftsman Homes & Design, West Pueblo, Colo., “the insulating concrete forms [ICFs] are the easiest to justify. The thermal envelope they create truly makes a critical difference for the homeowner and the planet that can't be beat. We won't build without them.”
The newest home Beverly and Dale Stevenart built in West Pueblo achieves the net-zero-energy goal. It combines ICFs, raised-heel trusses to allow the roof insulation to extend past the edge of the walls, staple-up radiant floor heating, thermal solar panels on the roof for heat and hot water, and a bank of photovoltaic panels to generate electricity. Because this home is connected to the electrical grid, they have no need for battery storage and would rather sell the excess power to the electric company. “They do net metering, which means they pay us wholesale and charge us retail for power, but we still end up ahead,” Beverly says. “There is a backup propane furnace, but on our last zero-energy home, the owners tell us that at the end of the year they made more by selling power to the utility company than they spent on propane, so it still ends up as zero cost.”
ICF construction, though, provides benefits that would make sense even if electricity was free: noise reduction, fire resistance, and pristine indoor air quality. Owen and Carol McKinney, owners of a Craftsman home, say, “This home is so comfortable, even the air feels great.” Another bonus is walls that resist natural and manmade attacks such as high wind or explosions. Dale Stevenart says he has noticed that ICF construction seems to attract security-conscious buyers, such as former military or national intelligence officers. “They like the idea of having concrete walls around them.”
Beverly Stevenart is primarily the designer of the Craftsman homes; her husband Dale is the builder. More than 30 years ago, Dale got started building energy-efficient homes in the Colorado mountains using 2x6 timber construction. Then he discovered that ICFs allowed him to achieve new levels in energy efficiency.
Starting as PolySteel dealers, the Stevenarts relocated to Pueblo for the sunny, solar-power-friendly climate. “In the beginning stages of our move to the area, we were planning only to market ICFs,” Dale says, “but we soon found that there weren't enough interested builders. So we began building homes again.” A lack of experienced builders often is cited as a factor holding back ICF construction.
The Stevenarts have found home buyers interested in ICF houses tend to be different. “People who are looking at concrete homes, energy-efficient homes, are generally more financially secure and know what they want,” says Dale. “Typically it's an educated buyer who is most interested in an ICF home.”
Selling ICF construction
Craftsman Homes & Design takes the “time-is-money” approach with prospective clients. Although they will work with a client for a few hours to determine if there is a basis for a project, they won't provide an estimate or any preliminary design work until the client has signed a memorandum of understanding and paid a $4500 deposit. “The deposit pays for the plans, a geotechnical investigation, structural design of the foundation, and a complete specification,” says Dale. “Fairly often our clients are owner-builders and we can offer them a complete ICF package along with consulting. The client could then take the complete package to another builder, although that has never happened to us.”
Although Craftsman markets ICF homes in a variety of ways, their most successful approach has been through education. Dale teaches four- to eight-hour seminars for those interested in ICF construction, either as owners or owner-builders. Over the years, most of their clients have been past seminar attendees.
Outside of the Pueblo area, Dale has conducted training sessions for builders interested in ICFs both for PolySteel, Cobourg, Ontario, Canada, and for the Insulating Concrete Form Association, Crofton, Md. Although the techniques are not difficult, learning how to do it right from those who have learned the hard way is critical to early success (see “Training To Build With ICFs”). Dale also teaches a seminar for ICF builders on how to sell in a down market. He has shown this is possible even in today's difficult climate: there were only nine building permits issued in Pueblo County in the second quarter of 2009, yet Craftsman Homes got three in October alone.
ICF construction tips
Craftsman Homes & Design has developed a few unique ICF construction techniques; here are some tips for builders.
- “There are so many ICFs on the market that they have become almost a commodity. There are some that are easier to work with, but the biggest difference is in the technical support and service,” says Dale. After working as a PolySteel distributor, they now use BuildBlock ICFs, which Dale considers very user-friendly.
- An important part of the job is to educate building officials to get them comfortable with the idea of ICF and energy-efficient construction.
- Although it may seem that foam ICF walls could not support a floor deck, that's actually not true. Dale prefers to install the plywood floor deck first and then pour the ICF walls. “This process requires kickers from the footer to the underside of the rim joist for stability. Interior walls are not necessary, but we do install the center beams and posts as required by the engineer.”
- Dale typically installs window and door bucks using V-Buck., made by Vinyl Technologies Inc., Logan, Utah. However, if wood bucks are used, it's important to build frames and not just screw the buck into the foam because it will blow out.
- Dale fills the blocks with 5½-inch-slump concrete, using a mix design developed several years ago by Frank Kozeliski in Gallup, N.M.
- To consolidate the concrete in the forms, he simply taps the outside as they are being filled, feeling that vibrators can lead to blowouts too easily. “This also lets the operator above know if the form is filled or not,” says Beverly.” If you've got someone tapping below, you can hear if the block is filled so you don't end up with voids.”
- Dale has filled blocks with lifts as high as 13 feet (in an emergency), and typically can empty a truck in 24 minutes.
- A prepour inspection is critical to make sure all of the bucks are screwed together, the bracing is right, and the rebar is all in place. “Also make sure that there are patch kits available in case of a blowout,” says Beverly. “Have a screw gun, screws, and some pieces of OSB handy.” Make sure the bracing is placed properly in the windows and doors. “It's a serious problem if they start to sag,” she says. “Because then the windows or doors won't fit.”
- A good way to increase the speed of construction is to preassemble wall panels in the shop then transport them to the site. Dale has panelized up to 12x8-foot ICF walls including window and door bucks. The ICFs are glued together or fastened with zip ties. Dale often uses jigs in the shop to keep the panels true.
- One thing to be careful of on sunny days when the blocks are all set up is that you can get badly burned from the sunlight reflecting off the foam.