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Garage Insulation with leftover materials and foam board

veeneck | Posted in General Questions on

I’ve got a finished, attached, unheated garage with an attic hatch for access. The ceiling has drywall on it right now. I’ve got a bunch of leftover EPS foam board and Rockwool batts from the basement I’m working on.

The garage ceiling has no insulation. The main option would be for me to just put the Rockwool between the trusses up there. Maybe add a top coat of blown in cellulose? Not sure if worth it.

My main question — can I make use of the foam board? Would it make sense to cut it to fit into the truss bays, and then cover with Rockwool? Or vice versa, with Rockwool in the bays and the foam board resting on top / glued?

Thanks for any advice – Ryan

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Replies

  1. andy_ | | #1

    Is the garage roof vented? What are you going to be doing in the garage that you want it insulated? ...or is this just as a thermal buffer between the house and the outdoors? What kind of climate are you in?
    The reason I ask is that it depends on what you'll be doing in there and how the structure was designed to perform. If you're going to turn it into finished space for something like a gym with a shower you're going to go about it a little differently than if you're just going to park a car in there.

    1. veeneck | | #2

      Vented roof, climate zone 4. Mainly just a place to park cars. We noticed that the garage held 10 degrees or so warmer than outside this winter. Maybe because both cars are electric and always passively on? Not sure. Anyway, the walls and garage doors are already insulated, so I’m just looking for something to do with leftover materials. Since it is an uncondition space, the insulation so far is probably a waste, but that’s the current situation.

  2. charlie_sullivan | | #3

    I would start by checking for air sealing details you want to take care of, mostly around the perimeter, maybe ceiling lights. After that's all done, go ahead and use all the insulation, EPS in first.

    1. veeneck | | #4

      Thanks, I’ll give that a shot

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