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  1. #1

    workshop insulation

    Greetings all!
    I have been a lurker on these forums for awhile and have used the info found on this site for many projects around the house. Now, I've got an issue that I would like to get some opinions on.

    I have a 12'x20' shed in my backyard that I have recently converted into a workshop/"man-cave" . With a brutal Houston summer just around the corner I need to figure out the best means to insulate the building. The shed is all wood with short walls and a "barn style" rounded type roof. In other words, it's almost all roof. Luckily, there are trees shading a good portion of the roof but even a few hours of sun beating down will turn the shed into an oven.

    Initially I was just going to use fiberglass batts as it looked easy to install and is relatively cheap. Now I'm wondering if I would be better off using a radiant barrier. The roof has 2x4 rafters spaced at 24" with, of course, plywood roof decking. You can really feel the heat radiating down from the plywood after a few hours of sun.

    I have a roll of foil radiant barrier that I could use right now, but I would be more than willing to buy something better if needed. One reason I am hesitant to use a radiant barrier is that I'm not sure if I'll like the look of so much silver foil in a space I'll be spending some considerable time in. But in the end, I want to be comfortable spending time in there during the summer months (cold weather is not much of a consideration). Also, I do have a decent window AC unit installed to pump in cold air.

    So, anyone have any insight on what would serve my needs best?


  2. #2
    Just a home owner here. I had a barn that had a metal roof and it turned into an oven in the summer from all the radiant heat from the metal roof. I installed 4' X 8' X 1" rigid foam sheets with a radiant foil on one side so the foil faced up next to the metal and nailed these panels against the wooden runners for the metal roof using nails with the wide plastic washers to hold the foam in place. I also caucked the seams with 100% clear RTV silacone to stop hot air infiltration from coming through the seams. It made a huge difference.

  3. #3
    Thanks for the reply Stan.

    I'm thinking I will staple up the radiant barrier material I have right now and see how much of a difference it makes. It's bound to be more comfortable than my garage has been!


  4. #4
    Sounds like a plan since you already have it in hand. Good luck.

  5. #5
    Join Date
    Feb 2003
    do you have wind most of the time? if so, maybe a "tent" over the existing about 3+inches above existing would work -- especially if the no shade is just at one spot --
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  6. #6
    Hmm, that sounds interesting. There is a pretty constant breeze but not real windy.

    1/2 of the roof is shaded all the time, with the other half receiving full sun about 1-4 hours each day. What exactly do you mean by "tent"?


  7. #7
    Join Date
    Oct 2005

    will need more

    The foil only has like a 9 R so you would need to use an additional R factor. Insulate and then use the foil but you will also need an air space and a little breathing room. Why would you be looking at this from inside are you not putting a ceiling up?

  8. #8
    Nope, no ceiling. There really isn't enough height for a ceiling. The side walls of the building are only ~4 ft. and then the roof starts at a steep angle for another 4 ft. It then angles again for about 4 ft to the peak of the roof and of course the other side is a mirror image. Think of a "rounded" barn style roof.
    So really it seems the only option is to insulate the bottom of the roof from the top of the side wall, up and around to the other side wall.
    Perhaps I could use a thin insulation between the 2x4 rafters and staple the radiant barrier to the 2x4's. What is the minimum recommended gap needed for the radiant barrier to be effective?

  9. #9
    Join Date
    Oct 2005
    Yes you can role the face fiber glass and staple the foil just poke a hole in the face so the air can move in or out and not be a vapor trap unless you can leave the ends open.

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