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Insulated Concrete Forms (ICF)

Roof and Gable Systems

About ICF's

If you are considering building with Insulated Concrete Form systems you already know that they are strong, well insulated, and fast.  Oak Ridge National Labs rated them the most energy-efficient system in a study of various wall systems under a rating system called "Whole Wall Insulation" which measures predicted and actual energy efficiency of various systems (see ).  ICFs were not only extremely efficient (measured as maintaining the highest percentage of mid-wall r-value), but also had very high r-value numbers to begin with.

Unfortunately, most ICF systems provide only the level walls.  Even when the systems are used in a gable end configuration, they are inefficient for slopes.  No ICF system provides a roof.  How do you maintain your energy efficiency for this system?

What do you do about gable ends and roof insulation?   All  the factors leading to your decision to use ICFs in the walls make most alternatives unacceptable for conventional systems.

Foam Core Panels

The same Oak Ridge test rated foam core panels as the second most efficient system.  The variation between ICFs and foam core panels was fairly small compared with the variation between foam core panels and the next best systems.

Foam core panels, also known as Structural Insulated Panels (SIPs), stress skin panels, enclosure panels, nailbase panels and curtain wall panels, are basically insulating foam (usually expanded polystyrene or polyurethane) laminated to oriented strand board, plywood, drywall, or other substrates to form a panel.  SIPs are often used in conjunction with ICFs- for gables ends, linking walls, and roof or ceiling systems.   R-values are comparable to ICF systems.

Strength in foam core panels is impressive. They are nearly as strong as ICFs with roof spans in the 12' to 18' range and crush strength, racking and shear values much higher than conventional stick-built.  The SIPs can also be used to create gable ends and ceilings.

Energy savings with SIPs are comparable to ICFs primarily because they are similar technologies.  Both rely on solid foam and solid substrates to bar infiltration and exfiltration and enhance energy performance.  Both are highly rated for their embedded energy characteristics.  Both have very low permeability ratings.  Both are highly regarded by EPA, Department of Energy, The American Lung Association, and The Allergy Foundation.

Why settle for stick built for the other half of your house?

A project using ICFs and foam core panels was recently dried in in Kingsport, TN.   This is what the system looks like as it comes together.


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This is the ICF form.

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This is the erected form system with concrete pumping into the forms.

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Here are the panels going up to form the roof system.


Another project in Ohio used a shed roof system over the ICFs.

A commercial project in Georgia used ICF walls with bar trusses to support foam core panels to insulate a new truck stop.

In Sewannee, TN, an owner/builder decided to use ICFs for the bulk of his walls, but used panels for one short wing that would need an internal floor (also panels), for all the gable ends, and for his roof.

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The gables and wing are up and, with the help of a small crane the roof is installed.

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Another view

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All done

If your ICF contractor does not provide an SIP alternative for gable ends and roof structure, please contact the Structural Insulated Panel Association at  to find a manufacturer or distributor near you.


This article was written by Butch Johnson, Marketing Director for General Panel Corporation, Inc. in Johnson City, TN.  Perma "R" is a manufacturer of Logix and the parent corporation to General Panel, a manufacturer of SIPs and stress skins and specialty laminated panels.   Perma "R"'s webpage is at .  General Panel's page is at , also .  I can be reached at .   Or call me at (423) 747-8710 (Eastern).