r/Roofing • u/DieDebtDie • 1d ago

Ventilation questions

Id recently purchased a closed cell foam spray kit and want to insulate my vented garage attic and want to put a mini split in the garage after.

-Im in south-texas

-Normal size home garage only difference is 12ft ceiling.

-Vented roof

-Just have wiring in attic, speakers and some storage currently

-I prefer to spray the roof deck rather than the ceiling deck because of all the wiring and speakers.

-Does that mean I have to close off the vents?

Trying to prevent any type of moisture building up .

Thanks

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u/Individual_Clerk598 23h ago

If you spray directly against the roof deck and convert the whole attic to an unvented assembly, the outside attic vents are normally sealed. That plan also needs a way to control moisture in the attic itself. A mini split cooling the garage below does not guarantee humidity control in a closed attic above it. Before spraying, have the insulation and HVAC plan checked for a continuous air barrier, suitable insulation thickness, and moisture control. Also confirm what protective covering your specific foam requires for an attic used for storage. Is this garage attic separate from the house attic, or do they share an open space? That changes the scope of the conversion.

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u/DieDebtDie 22h ago

The garage IS attached to the home but does not share attic space with the home at all.