How to Foam Insulate a Shed
- 1). Remove the shed's existing roof so the exterior roofing structure is exposed. Lay OSB (oriented-strand board) or plywood across the roofing structure, and attach it, using a hammer and galvanized or stainless steel nails.
- 2). Lay vapor sheeting, a weatherproofing material that keeps out moisture, over the board. Use a staple gun to staple down the sheeting over the boards.
- 3). Use a measuring tape to measure the area of the roof. Measure and mark foam board panels to the correct size to fit on your roof. Score the panels with a razor knife, and snap the panels at the score mark to cut them to size.
- 4). Use a glue specifically designed to adhere to foam board panels, which you can purchase at most home improvement centers. Apply the glue to the foam boards according to the manufacturer's instructions, and place the panels over the vapor sheeting. Leave a 1/8-inch seam between each foam board panel. Place strips of duct tape over each seam.
- 5). Lay down firing strips, beginning at the top of the foam board panels and working your way down. Position the firing strips horizontally across the panels. Position an additional firing strip across the top and bottom ridge and center of each panel.
- 6). Reposition the metal roof on top of the shed. Attach the roof to the previously installed firing strips, using a hammer and galvanized nails. Apply a bead of caulk to the nail heads to prevent damaging the foam board panels, and to create a small amount of space to promote airflow between the roof and panels.
Source...