PATH - A Public Private Partnership for Advancing Housing Technology
PATH Case Study
Easy Concrete Exteriors Create New Opportunities for Seasoned Pro
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[IMAGE: Vertical ICFs are strong enough to withstand many tons of weight without backfill.]
"Because we didn't want to use one of our customer's homes to experiment with a new method of building, we decided to try vertical ICFs on the home we were building for ourselves. The manufacturer sent us a manual with our first order and we learned how to use them from reading that."
"The manual and its drawings make everything very easy to comprehend. This makes everyone involved--from the engineer and the architect to the subs and inspectors--comfortable with the product because they know how it goes together and how it shouldook as it's going up. We also always give a copy to the county inspectors so they have it on file and to the engineer, architects, and draftspersons for their drawings and reports."
Despite the manual, Arrington did still have to educate some of her subcontractors so they could adjust their practices.
"For example, the HVAC contractor had to recalculate the size of the HVAC system to account for the higher level of insulation that vertical ICFs provide. It was also necessary to plan where the exterior wall openings for the electrical and plumbing devices would be located. But thankfully, getting the subcontractors familiar and comfortable with the changeover only takes one project!"
HOW IT WORKS
Vertical ICFs are stay-in-place concrete forms that serve as a functional part of the wall after the concrete is poured. While most ICFs come in blocks, vertical ICFs form the entire height of the wall. Vertical ICFs require less bracing because their monolithic wall sections are sturdier than traditional block ICF walls. Composed of two polystyrene panels held together by plastic or steel I-beams, each vertical ICF panel is two-and-a-half inches thick, forming a one-foot-wide wall. Like block ICFs, concrete is poured into the space between the polystyrene. When filled with concrete, they form dimensionally straight, energy-efficient walls.
In the first project, Arrington discovered she had used too much bracing.
"We used two whalers--one on the inside and one on the outside with walkboards above the inside whaler, all the way around the building, plus outside corner bracing. We have since adapted our method. Now, for most projects, we only use corner bracing on the outside corners; inside, we use scaffolding to walk on as we do the pour. We also reuse the bracing to construct the interior walls of the house, which we typically build out of 2 x 4 studs."
EDUCATION IS KEY
From previous experience, Arrington knew that educating the inspector in advance would be essential.
"We made an appointment with the inspector ahead of time and sat with him for a while to explain the technology," says Arrington. ìSince he was from upstate New York where vertical ICFs are used more frequently, he was already familiar with the product. Some other inspectors have required a bit more education, but they have all come around. These days, we often approach inspectors ahead of time to educate them about the product so the inspection process will go smoothly."
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Content updated on 9/5/2006
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Affordable Housing Providers