Attachment of Heavy Cladding Over Foam With and Without Drainage Gaps

The aim of this research was to identify alternate and/or expanded design and installation guidance for the application of heavyweight claddings such as stucco and adhered masonry veneers over rigid foam insulation on light-frame walls and potentially provide the basis for follow-on qualification testing to support a future code proposal.

Wall samples were tested in the lab for deflection and cracking due to gravity loading. The baseline set of specimens was designed to inform potential calibration of the TR-12 dowel equations for the unique case of cementitious claddings which include minimal penetration of the fastener through the material and transfer of the cladding load to the fastener via an embedded lath substrate. Three fastener types were tested: staples, nails and screws. Additional lines of inquiry introduced drainage gaps into the wall assembly and tested the effect of foam thickness and lath type. Test matrix details subsequent to the baseline set were adjusted in response to demonstrated performance and to more fully explore opportunities for highly constructible or effective configurations.