insulating garage.

[porsche911]

Just moved into my house and working on insulating the garage. Just got the wall sprayed today. (not sure if its open or closed cell, perhaps something i should ask the installer)

My question is do i need vapour barrier over spray foam, or can i just put the osb boards right over the spray foam. Im used to doing foam batts where a vapour barrier is required so im leaning towards it, however i do know the spray foam also seals off flow. Would using a 6mil vapour barrier hurt if i used it regardless. Ill be needing it for the ceiling where it'll be foam batts so i figure for an extra $70 or so i can buy a large roll to do the walls where its sprayed.

Thanks!!

 

[scoob8000]

From what research I've done, open cell needs a vapor barrier, closed cell does not.

 

[Jimmies63]

Closed cell here. No vapor barrier needed for that.

 

[porsche911]

ok. I shall call the sprayers and find out which one was used.

 

[JCByrd24]

Where are you located and what are you doing in your garage and heating it with? You don't need a vapor barrier if there is no moisture in your garage. Most climates are dry in the winter and a garage doesn't have cooking, showers, clothes drying, etc to cause moisture. You likely can skip VB either way. Also, OSB on the interior walls is a vapor retarder so again, you should be all set with nothing additional.

 

[gpalmer77]

Neither type needs a vapor barrier in any normal application. Vapor diffusivity rates in open cell are very low, no vapor retardant barrier is required. I researched this before spraying open cell into the roof of my house.