Spray Foam Over Wood Purlins Metal Roof

Siding and roof are tin sheets.

Spray foam over wood purlins metal roof.

We ll add a vapor barrier so the moist air does not flow up through the insulation and condense on the roof. 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. 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. 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.

My plan was to have spray foam sprayed directly on the tin sheets. I have a 30x60 metal building barndominium in the san antonio tx area. Of course everyone looks for an out when it comes to warranties and the reality is a good warranty protects the seller manufacturer far more than it. Traditionally we ve insulated the roof panel to try and keep the temperature on the panel from reaching the dew point.

The big picture concern is actually more about trapped moisture than whether the substances that make up spray foam insulation will corrode steel or metal sheets. 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. But a preinstalled membrane may be even more effective at removing condensation. This type of assembly is designed to dry to the interior so the assembly should never include an interior polyethylene vapor barrier.

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. It is going to be a residential home inside. 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. Installing metal roof insulation is not a difficult.

The problem with using. 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.