This should not be a concern when applying foam to the underside of a roof deck.
Spray foam insulation on roof deck.
Polyurethane or polystyrene spray foams can provide thorough coverage to roof rafters and attic walls in much less time than is needed for other materials.
In the northwest where foam has been sprayed directly to the underside of roof decks for over a decade the building officials interpret the code to require removal of existing insulation.
Bare foam board one sided sheathing board or double sided which is also reference as structural insulated panels.
It rots roofs people have told me.
But spray foam insulation used at the underside of the roof deck would need to be covered by a thermal barrier and intumescent coatings are commonly used.
Unlike solid insulation products that require careful measurement cutting and fitting spray foam can cover even the most uneven surface instantly.
As air impermeable insulation spray foam insulation can be used in such applications.
Both open cell and closed cell spray foam insulation adhears extremely well to the underside of roof decks and the rafters surrounding them when installed correctly.
Rigid foam board is just above the roof deck or an exterior insulation option.
The previous four options are all used beneath the roof.
Unvented roofs with spray foam applied to the underside of the roof deck have been used since the mid 1990s.
Open cell spray polyurethane foam or closed cell spray polyurethane foam ccspf insulation can be sprayed along the underside of the roof sheathing to provide a conditioned and insulated attic space that can be durable and efficient in.
It typically has 3 variations.
The code allows for insulation directly to the underside of the structural roof sheathing providing the unvented attic is contained completely within the.
Murmurs and hearsay about open cell spray foam insulation have been gaining traction for a while.
I have not heard of any evidence to support your theory.
Spray foam insulation applied on the underside of the roof deck in cold climate commercial buildings allows for a significant reduction in condensation potential particularly compared to interior air permeable batt systems.
Not long ago someone even told me that in florida roofing companies won t let their workers go up on roofs with open cell spray foam because the roofs are so spongy the guys fall right through.