Alternative Framing Materials in Residential Construction: Three Case Studies

Authors: NAHB Research Center Inc.    

As lumber prices have risen, builders and other providers of affordable housing have sought lower-cost alternatives to conventional wood framing for residential construction. Alternative Framing Materials in Residential Construction: Three Case Studies compares the cost competitiveness of three of the most promising, commercially available building systems foam-core panels, light-gauge steel framing, and welded-wire sandwich panels with conventional materials and techniques.

Light-gauge steel framing most closely approached the cost of wood framing. In four "demonstration" houses constructed using this material, the lower material and equipment costs associated with steel-framed interior and exterior walls brought its total cost to within 7 percent of the cost of wood framing even though the alternative system required 30 percent more labor to construct. Framing the roofs with light-gauge steel took 50 percent more time and was one-third more expensive. In the construction of three "demonstration" houses using foam-core panels (foam material sandwiched by two facings, typically oriented strand board, waferboard, or plywood), the exterior walls actually required slightly less time per linear foot to construct than conventionally framed walls. However, the much higher material costs for the foam-core panels made the total cost more than twice the cost of conventional walls. But the roof constructed of foam-core panels took 50 percent longer and was nearly three times as expensive to build as a wood-framed roof.

Welded-wire sandwich panels consist of a polystyrene or polyurethane insulation core surrounded by a welded-wire space frame; a layer of concrete is applied over the wire mesh. A demonstration house using these panels for the exterior walls required two-thirds more labor per linear square foot than the wood frame method. Total costs for exterior walls of welded-wire sandwich panel and faced by concrete with a sand finish were 63 percent higher per linear foot than wood framed walls faced with siding and brick. Roof framing with welded-wire panels required eight times the labor of wood framing for five times the total cost.

The study concludes that although none of the three alternative systems are currently cost competitive with conventional wood framing, materials and methods could be mixed to construct more affordable housing. For example, a combination of steel framed walls and wood roof trusses could yield lower overall costs if the price of lumber continues to rise.

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