Open cell spray foam can also be used to create an unvented attic in cold climate zones provided code requirements for a vapor retarder are followed.
Open cell spray foam metal roof.
In our neck of the woods closed cell foam costs about 56 more than open cell.
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 would be better to use a closed cell 2 pound density foam because it doesn t expand as much as open cell and is more likely to fill voids but not go through them.
There are some cases where i could see some challenges.
Moisture from indoors can diffuse through the foam and find the cold roof sheathing where it accumulates and eventually rots the roof.
Open cell spray foam.
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.
However i own a spray foam rig and i wouldn t bother putting more than about 8 of open cell or 5 closed cell.
We already know open cell spray foam is risky in cold climates.
I prefer spraying open cell over the rafters when possible because it avoids shrinkage problems that can occur with such foams.
Spf insulation can be open cell or closed cell.
Most steel roofing is factory finish painted which adds yet another barrier surface in the interior primer paint coat which further isolates the steel from the spray foam.
Closed cell foam provides better insulation than open cell and also functions as an air barrier.
Some spray foam manufactures have tested primer coating products that result in the formulation of a class ii vapor retarder directly on the surface of the open cell spray foam.
Open cell foam provides insulation and air sealing for a building but is water and vapor permeable.
Strong material that can strengthen walls roofs structure.
How ducts in an unvented attic should be installed.
Less common of the two types of spray foam open cell is mostly used for residential and commercial insulation.
As a result in iecc climate zones 5 and higher building codes require the use of a vapor retarder if you install open cell spray foam.
One would be if someone went on the cheap and used open cell spray foam rather than closed cell.
Spf insulation consists of isocyanate and polyol resin that is chemically combined and applied to surfaces using a spray gun.