Step 4: We raise the SIPS. The SIPS are secured in two ways: the wall panels are nailed to a sill plate which is glued and screwed directly to the subfloor, and all panels are nailed and/or screwed directly to the exterior timbers every 16" to 24" with 7" to 12" ringshanks or panel screws. Further, wherever two panels meet we apply a special sealant that literally melds the two sections of polystyrene along the seam into one. And finally, where necessary we insert 2x splines between panels to join them structurally.