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INSULATING CONCRETE FORMS
LIGHT AND TIGHT
Concrete walls alone have very little insulating value, about R-.8 per inch. Yet concrete can last forever, or nearly so, if it’s protected from erratic moisture changes and freeze-thaw cycles. That’s what makes ICFs an excellent structural system. They enclose both sides of a poured cement wall within a water-resistant cocoon of rigid foam. Another advantage to ICFs is that their assembly is quite simple, and the completed walls have an average insulating value of about R-22.


INSULATING CONCRETE FORMS


VIRTUES
> Very little air infiltration
> Lightweight forms— assemble easily
> Thermal mass of concrete slows temperature swings


CAVEATS
> Exposed foam may need protection
> Some brands require additional furring strips to attach drywall and siding


 


GLOSSARY OF TERMS
KNOW THE LINGO
> Dimensional Lumber
Wood that has been cut and shaped from a single tree, typically used for framing.


> Load-Bearing Wall
A wall that helps hold up the house. Interior walls may not be load bearing, but external ones almost always are.


> Engineered Wood Products (EWP)
Structural products made in the factory from industrial wood scrap or fast-growing species, assembled with resins under extreme pressure.


> Oriented Strand Board (OSB)
A type of engineered wood panel. The thickness of OSB used in most SIPs is 7/16”.


> Fly Ash
Controversial waste by-product from coal- fired power plants. Used as a filler in some—but not all—brands of lightweight concrete blocks.


> Sound Transmission Class (STC)
Refers to how well a wall partition attenuates sound. Products such as ICFs have high STC ratings and greatly reduce noise levels inside the home.


 


LIGHTWEIGHT CONCRETE BLOCKS
LASTING VALUE
Lightweight concrete is a structural material that’s been around since at least the 1920s. To create these blocks, the manufacturer replaces a portion of the concrete with something lighter and better insulating, such as an industrial waste product like fly ash or petroleum-based polystyrene. Some companies (see Liteblok, below) use a temporary agent that leaves nothing but air gaps behind. Fly ash is controversial and may contain mercury or other toxins. Manufacturers should provide data showing they have screened any post-industrial waste used in their products.


LIGHTWEIGHT CONCRETE BLOCKS



VIRTUES
> Easy to handle
> Less energy intensive than concrete
> Durable and termite proof


CAVEATS
> May not be locally manufactured
> Contractors/masons may need training
> Waste components should be tested/ verified


 


R-CONTROL SIPS
Made with OSB laminated on to a termite-resistant EPS insulation core, R-Control SIPs are state-of-the-art. The core is also treated with EPA-approved mold resistance. A 6 1/2” panel is a respectable R-23. www.r-control.com


BOISE CASCADE FSC CERTIFIED FRAMING LUMBER
Boise Cascade’s FSC certification shows that they take sustainable forestry seriously. The company sells its framing lumber through more than 30 distributors nationwide. www.bc.com


23
GreenBuilder 11.2010

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