Fiberglass Foundation

Fiberglass Foundation

Foundations are not glamorous. When most people think about architecture, they’re not thinking about the foundation. But there’s a foundation under every building… because there needs to be. Foundations were once made of stone. More recently, most have been made of concrete. Heavy stuff.

Now, you can have one made of fiberglass composite.

The Epitome system, made by Composite Panel Systems of Eagle River, WI, is a foundation wall system that is fully load-bearing and more. The panels are 9 feet high and 24 feet long. They sit on an 18” wide concrete footing (yes, you still need some concrete), but the panels can support 9000 lbs./lineal foot, twice the vertical load that the footing can. More important, they can bear a horizontal (in-plane) load equal to six times the weight of the sand backfill.

The panels are formed on a urethane foam core, with glass fiber composite skins of 3/16”-1/4” on each side. They include integral 2X4 “studs” 16 inches on center. The body of the panel is 3 3/8” thick, with an additional 3 ½” “stud, for a total thickness of 7 inches… considerably thinner than the typical concrete foundation wall. Unlike concrete foundation walls, they are light enough to be installed with a light-duty crane of material handler, the work can be done in any weather, even under freezing conditions (try that with concrete), and you don’t have to wait 28 days before you can build on them.

The body of the panel gets its high horizontal load strength from integrated FRP I-beams running vertically, connecting inner skin to outer skin, spaced every four inches.

Because of the 3 inches of foam, the panels achieve a thermal insulating value of R=16.5. If the basement is finished with drywall (is doesn’t have to be, but it can) additional insulation may be placed between the studs to achieved even higher R values, and the FRP studs themselves provide little if any thermal bridging.

Put all of that together and the panel constitutes a wall structure, insulation, stud framing, vapor barrier, top plate and seal. Costs are reported to be about 15-20% more than a concrete wall, and with elimination of the need to add framing and moisture-sealing, may end up being just about comparable.

The Epitome system has been code-approved nationally, but has not yet been tested for seismic performance. (Since people living in areas of high seismic activity often don’t build basements, seismic has not been the manufacturer’s highest priority.) The walls could also be used above ground as load-bearing exterior walls – in fact, they are overbuilt for that application – but they are not being marketed that way… yet.

Images courtesy of Composite Panel Systems, LLC