Insulation Between Osb And Siding

This detail is used with both new construction and also with renovation work.

Insulation between osb and siding.

Yes closed cell high density foam cavity insulation applied to the inside of osb sheathings that are in turn covered on the exterior with impermeable foam sheathings is risky. Many houses built today have a double wall type of insulation with fiberglass batts fastened between the studs on the inside and rigid foam board over. If you prefer to use polyiso without a foil facing feel free to do so. How to install rigid foam under siding.

Below are some of the design details along with the benefits. Unless you provide a small gap between the exterior face of the osb and the back surface of the foam sheathing to provide for some hygric redistribution. Installing foam board insulation under vinyl siding today more than ever before homes are being built with foam board insulation installed on the outside of the sheathing and under the siding. Everything on the exterior side of the polyiso the furring strips and siding will dry to the exterior while everything on the interior side of the polyiso the osb studs and fluffy insulation will dry to the interior.

Hot sun can overheat wood siding causing it to dry excessively and crack. Foam is less permeable to water vapor and the back of the siding stays wet as the face of the siding dries. Wood siding needs an air space between its backside and the face of foam sheathing.