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Insulating a Roof?

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  • Insulating a Roof?

    Would insulating a roof be a good or bad idea?

    Icynene? Open cell? Closed?

    Thanks.

    J.C.

  • #2
    Re: Insulating a Roof?

    the guys who do spray foam in our area do the underside of the roof surface, and not the ceiling surface. the idea being that it gives the rising heat a place to go. and your attic stays within a few degrees of the main part of the house.

    This does require an air exchanger on the hvac system, otherwise the house can get moldy.
    No, it's not rocket science, it's plumbing and unlike rocket science it requires a license.

    Comment


    • #3
      Re: Insulating a Roof?

      Originally posted by MoJourneyman View Post
      the guys who do spray foam in our area do the underside of the roof surface, and not the ceiling surface. the idea being that it gives the rising heat a place to go. and your attic stays within a few degrees of the main part of the house.

      This does require an air exchanger on the hvac system, otherwise the house can get moldy.
      Thanks. It seems like a good place to insulate. Especially warmer climates 'cause any of us that have been in an attic in the summers know that it just cooks off of that roof down into the attic.

      J.C.

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      • #4
        Re: Insulating a Roof?

        Attic insulation is always a good idea.

        Reflective roof coatings are supposed to make a big difference too, but I think they're unsightly.

        If you have an enclosed attic, there are several things you can do.

        With some more information about the structure, I can give you more specific tips.

        Back when I was with a GC, I became a "certified weatherization technician"

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        • #5
          Re: Insulating a Roof?

          Originally posted by radar_40 View Post
          Attic insulation is always a good idea.

          Reflective roof coatings are supposed to make a big difference too, but I think they're unsightly.

          If you have an enclosed attic, there are several things you can do.

          With some more information about the structure, I can give you more specific tips.

          Back when I was with a GC, I became a "certified weatherization technician"
          Not necessarily "attic insulation" which is typically directly over the ceiling of the living space. I'm talking about spraying icynene (or some other insulation) directly on the sheething of the roof. Underneath the shingles, metal etc.

          Good or bad?

          Thanks.

          J.C.

          Comment


          • #6
            Re: Insulating a Roof?

            And would it get too hot/cold without the airspace from the soffit to the ridge vent? Should another sheet be in-between to make an airgap for relief? Thinking...

            Thanks again.

            J.C.

            Comment


            • #7
              Re: Insulating a Roof?

              I would not block off the airflow from an open soffit, but the rest of the roof could be a good idea.

              We don't see that alot here as we're generally more concerned with cold than heat.

              I've have heard about it, and it seems to me that you could really reduce the heat picked up by the roof.

              Refletix (sp) is the product that comes to mind, but I suppose you could spray it if you wanted.

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              • #8
                Re: Insulating a Roof?

                Spraying directly on the outside facing sheeting would be really weird on an asphalt application - how would you level things and nail through the goop?

                How would you then strip the asphalt down the road?

                A better solution would be a high density synthetic roofing underlayment like Triflex or Titanium - serious vapor barrier.

                Ideally, you do it in a permanent roofing set up with proper ventilation, since the roof will be really tight on the outside. As well, aluminum would be a cooler, reflective metal than steel. Ideally a shingle application.....

                Then, you get up in your attic and spray the underside of that roof and spray your icynene(or other-named equivalent).

                Should keep things nice and cozy in the winter and a lot cooler in the summer - probably cut down on trapped attic heat by at least 30 to 40 percent.

                Easy on the A/C..........
                Last edited by tinmack; 07-31-2010, 09:51 PM. Reason: speeling
                I'm on "The List" and I love it!!

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                • #9
                  Re: Insulating a Roof?

                  I always meant spraying the underside of the roof. Got to give me at least a little common sense credit.

                  But then I got to thinking that it might cause a temperature increase on the material and what would that do?

                  I'm thinking there should be an air gap between the bottom of the roof sheathing from the soffit to the ridge vent. Then spray over whatever is used to make that air gap.

                  J.C.

                  Comment


                  • #10
                    Re: Insulating a Roof?

                    This is what Iw as talking about: http://www.reflectixinc.com/basepage...&pageIndex=530

                    Some of the stuff they claim is junk science in my opinion, but it's well suited for that application you're talking about.

                    Just staple it up... No renting a sprayer.

                    Comment


                    • #11
                      Re: Insulating a Roof?

                      Originally posted by radar_40 View Post
                      This is what Iw as talking about: http://www.reflectixinc.com/basepage...&pageIndex=530

                      Some of the stuff they claim is junk science in my opinion, but it's well suited for that application you're talking about.

                      Just staple it up... No renting a sprayer.
                      Thanks. I have seen that stuff. Does seem "VooDooish".

                      Don't know if I would use it if I were building something, but I think I like the open cell & closed cell icynene.

                      Done a couple of jobs and it seems to not only insulate but strengthen the overall structure.

                      Thanks again.

                      J.C.

                      Comment


                      • #12
                        Re: Insulating a Roof?

                        No expert but my thinking is that the immense heat in the attic is transmitted from the shingles through the plywood and into the attic space. If you seal the plywood surface that is convection cooled I think you would cook the shingles and drastically shorten their lifespan similar to closing off the soffit vents but worse. For my money the insulation is best applied in the attic between the living space and the attic space leaving the underside of the roof surface open to cool via convection between soffit and ridge.

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