The house had a conventional truss roof structure from the start. Despite the general contractor’s love of SIPs, the spans, point loads and floor layout did not lend themselves to the efficient use of roof SIPs. Discussions with the GC revealed the usual concerns over air leakage from the conditioned space into the vented attic. Our solution? Specify a nailbase panel that was attached to the underside of the bottom cord of the truss package. As opposed to the structural version (a SIP) the nailbase panel has only one OSB skin laminated to the foam core. After measuring distance between trusses, the crew transfers measurments to nailbase panel, then they drill and preinsert panel screws. Meanwhile another member of the crew is using sealant on the edging and splines already in the ceiling. The nailbase panel is easily set with the aid of a drywall hoist. The 2400 sq ft of ceiling nailbase shown here was installed in 10 hours using a four man crew.
The 3 1/2″ core combined with a 7/16″ skin provided a flat and secure substrate to on which to attach gypsum board. The GC plans to blow in cellulose on top of the nailbase panels to increase the R-value to R-38. Results? Happy GC – he gets an airtight ceiling which will help insure a successful blower door test. Happy Framer – the interior framing installs faster due to the nailbase ceiling. Happy Drywall Contractor – the gypsum installs faster and with considerably less waste. Happy Owner – gets greater comfort, lower energy bills, and a roof system with energy-efficiency at the budgeted cost.