PATH - A Public Private Partnership for Advancing Housing Technology
PATH Case Study
ndustrial-Strength Homes for Everyday Living
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[IMAGE: Concrete form liners are used to create exterior finishes ranging from brick to stone, which are painted in the field.]
The home is also equipped with hurricane strapping to securely connect the roof to the walls; tape-sealed roof sheathing joints; hail-resistant roof shingles; and impact-resistant windows, doors, and skylights. The wood truss roof was constructed to meet the same hurricane requirements used in Miami-Dade County, Florida.
"We use precast concrete panels from Dukane Precast that include aggregate from recycled slag, bio-based insulating foam, and far fewer chemicals and potentially harmful toxins than other building methods."
"Our precast concrete homes have scored as high as a 91.6 using the Home Energy Rating System (HERS). Therefore, clients can expect a home that is not only safe and durable, but also extremely energy efficient. Because of the tightness of construction (air change rate = 0.07), we use energy recovery ventilation (ERV) or heat recovery ventilation (HRV) systems to circulate fresh air while improving energy efficiency."
Dukane's double-wall precast concrete system consists of two form-finished concrete panels with reinforcing steel and a bio-based polyisocyanurate (polyiso) insulating foam sandwiched between each panel. Polyiso is also used for roofing and appliance insulation. It has a high R-value and good moisture resistance. Higher density foam is used on exterior walls; lower density foam is used for sound attenuation on interior walls. The exterior walls have an insulating value equal to R-21 from the footing to the roofline.
PRECAST CONCRETE PANELS
Precast concrete panels are cast and cured in a controlled factory environment, which helps ensure panel quality and consistency. Panels can be installed quickly with the use of a crane and then immediately backfilled after waterproofing takes place. Precast panel construction also generates less waste than conventionally framed site-built housing.
Read the PATH Tech Spec.
Conventional waterproofing methods (backer rod and caulk with a ribbed plastic board and filter) are used to protect sub-grade portions of the wall panels. Maximum panel height is 12 feet and can be adjusted to accommodate ceilings from 9 to 11 feet. The standard interior and exterior wall finishes are form-finished smooth, but there are a variety of other wall options. For example, customers can request a form liner that resembles brick, stone, or a roughened slate-like surface. Another option is to use textured paint or simply a knockdown stucco finish.
INSTALLATION AND TRAINING
"When using precast concrete panels, more planning and coordination is needed ahead of time," says Bock. "As with anything, the first attempt is the hardest and it gets easier from there."
"Pouring and insulating the panels for a typical single-family home takes the factory about 3 days. They can be delivered as soon as the footings are poured and cured. The panels achieve 3,000 psi overnight with an ultimate strength of 6,000 psi after a few days of curing. It's best to wait at least 30 days before painting the panels."
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Content updated on 9/6/2006
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