Frost Protected Shallow Foundations

PATH Case Study

Frost-Protected Shallow Foundations

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"We set in electrical boxes and blockouts for windows and doors and then pour the concrete walls on the ground. We stand the perimeter walls, and place them inside the footing trench on leveling pads. After footing trenches are backfilled to support perimeter walls, the slab is poured over reinforced steel, polystyrene insulation, and a sand base to create a concrete home insulated from frost penetration. Our construction time just for the slab and concrete walls is typically three to four weeks for a larger custom home (2,200-3,500 square feet) and only one week for a smaller home (1,400-1,800 square feet)."

"For the Abbey Road project, we had to come up with a method of termite protection that would meet stricter code requirements. We used sheetmetal flashing at the transition between the polystyrene below grade, and polyiso above ground. The homeowner was adamantly opposed to any type of pesticide or soil treatment anyway, so the sheetmetal flashing was the proper solution."

SCHEDULING, AVAILABILITY, & JOB SITE STORAGE

"Lead-time and transportation have not been a problem for us," Fosdick says. "When storing the 4' x 8' sheets of insulation at the jobsite, be sure to place plenty of weight on top to avoid losing sheets to the wind. On a previous job, we learned wooden pallets were not heavy enough and found ourselves chasing sheets. Protecting polystyrene foam stored on the jobsite from sunlight is also important since exposure to UV rays can damage the insulation."

TRAINING

"All of Tierra's concrete work is performed in-house, so our crew is familiar with FPSFs," Fosdick says. "The insulating panels are built into our shop drawings and easily incorporated into the process of building walls since the insulation is the first thing we place in our casting form. After the first house, our crews were competent installers and it became part of our standard wall construction method. There were no major learning curves."

The finished product earned a 2006 Energy Value Housing Award.

"Training for subcontractors is critical. On a previous project, a plumber didn't understand the necessity of the insulation barrier. He was careless about replacing insulation that was damaged when he put pipe penetrations through the foundation walls. Training for subcontractors is mainly a matter of getting them to respect that the insulation and its placement is important to the integrity of the home."

A WHOLE BUILDING APPROACH

"When considering new technologies, it is important to not isolate or compartmentalize," Fosdick says. "Instead, take a whole-building approach, starting with the design and building envelope. The combination of several well-chosen technologies--in this case passive solar design with thermal mass for heat storage, proper insulation, quality windows, high efficiency equipment, ENERGY STAR® appliances and ENERGY STAR lighting- will improve the quality and durability of the home much more than any measure on its own."

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Content updated on 9/1/2006

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