Spray Foam Over Wood Purlins Metal Roof

It is going to be a residential home inside.

Spray foam over wood purlins metal roof.

Install a layer of closed cell spray foam against the underside of the steel roofing or roof sheathing and fill the rest of the purlin cavity with an air permeable insulation. Personally i am hard pressed to see how it is the application of closed cell spray foam insulation on the interior of the steel roofing would influence the life of coatings on the exterior. There seem to be no chemicals in spray foam that could react with steel or the galvanized protective coverings on the metal siding and roofing panels. My plan was to have spray foam sprayed directly on the tin sheets.

Another thought if you plan to spray foam insulation onto the underside of a metal roof on purlins install some type of underlayment tyvek etc over the purlins before applying the metal. The insulation then attaches to the underlayment and should you ever have to remove a piece of metal for whatever reason you do not destroy the. The problem with using. But a preinstalled membrane may be even more effective at removing condensation.

I have a 30x60 metal building barndominium in the san antonio tx area. Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point. It has red iron main frame with all 2x6 wood framing 16 on center on walls in between i beams and 8 steel purlin on roof. We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof.

Metal roofing panels rated for architectural use attached to purlins horizontal pieces of wood or metal fastened to roofing trusses are structurally sound when installed according to your roofing manufacturer s instructions and local building codes. This type of assembly is designed to dry to the interior so the assembly should never include an interior polyethylene vapor barrier. Siding and roof are tin sheets. The metal roof has been a very popular roofing material for some time but people have just started using insulation within the roofing system as a means to block out sound and keep heat in.

For many applications a layer of plywood underneath your metal roofing is an unnecessary expense. To help with energy conservation and noise pollution many office buildings and homes use metal roof insulation as a way to cut down on these issues.