Roofing Foam Board

As my article states you need a minimum of about 1 5 inch of eps 1 inch of xps or 1 inch of polyiso.

Roofing foam board.

The panels need to fit together tightly to help prevent warm air from leaving the top of the building. Rigid roof insulation board. Composed of a closed cell polyisocyanurate foam core bonded in the foaming process to retroplus roof board on one side and a glass reinforced facer on the other. The 4 x8 sheets of rigid foam board insulation were then laid out in a staggered pattern across the entire surface of the flat roof.

Retroplus roof board is an expanded perlite mineral aggregate board. Attach the tongue and groove insulation boards to the concrete wall with adhesive. Rigid foam is produced in various size panels 4 ft x 8 ft 4ft x 4ft etc. Use a premade kit for this type of project.

For new construction use rigid boards to insulate slabs and the outside of foundation walls. Attach to deck board. If you want to install rigid foam above your roof sheathing in climate zone 3 then 1 2 inch of rigid foam board is not ideal this rigid foam layer needs a minimum r value of r 5 and that s impossible with 1 2 inch of foam. Foam board insulation is easy to cut with a circular saw with a masonry blade or scored with a utility knife and snapped like you would drywall.

To attach the insulation you can use screws with large washers a special adhesive made for adhering foam board insulation or for smaller pieces you can seal them in with caulk or spray foam.