Builders should consider these costs before specifying open cell spray foam.
Open cell spray foam in attic.
Open cell spray foam insulation doesn t store the moisture.
Spray polyurethane foam is a strong expansive product that quickly works to seal various cracks and holes in your crawl space attic and walls.
It s just a pathway.
This makes the foam a softer more flexable material.
Closed cell foam can also increase the racking strength of attic walls which.
This airtight seal helps to decrease homeowner costs including utility costs.
Open cell foam is full of cells that aren t completely encapsulated.
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.
It has a relatively high vapor permeance 3 perms at a thickness of 6 allowing water vapor to migrate to the roof decking at night and back into the attic air in the daytime.
It s the wood decking that stores the moisture though.
It has been said that insulating with spray foam insulation at the roof line will lead to moisture problems with the roof sheathing.
The role of open cell spray foam.
Creates a strong airtight seal.
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.
In other words the cells are deliberatly left open.
A spray insulation is referred to open cell or closed cell because of the difference between the small bubbles cells that make up the foam.
Moisture is also another huge issue when it comes to spray foam insulation in an attic.
Open cell foam weighs 1 2 pound per cubic foot and closed cell weighs 2 lbs per cubic foot.
Open cell foam has an r value of about 3 5 to 3 7 per inch while closed cell foam has an r value of about 6 per inch.
Spray foam is resistant to water.
Whereas too little spray foam insulation can leave for thermal bypass because of the complete lack of insulation in the attic.