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Materials for an Energy-Efficient Workshop

Shaun A | Posted in General Questions on

I am in the middle of designing a nice detached garage that will be my workshop. I want it to be as efficient as I can get but still be cost effective. I usually build with Zip but the cost here right now for it is $52/sheet compared to regular 7/16 is $15/sheet. Should I save the money per sheet and just tape the seams and use house wrap? Or should I stick with the Zip? I love the Zip and it is what I know best but I would like to save some money since this is my personal build. I feel like I could still get a bomber proof WRB with regular OSB and take that saved money and put it towards other things. Open to other suggestions also. Thanks!

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Replies

  1. Expert Member
    Zephyr7 | | #1

    You can do a good job with regular ol' housewrap and OSB/plywood sheathing if you're careful with the details. The big advantage to Zip is that it saves a construction step since the WRB is integrated into the sheathing product.

    If you want to get some extra efficiency with your savings, you'd be better off putting up an exterior layer of polyiso with the extra money you save from not going with Zip.

    Bill

    1. Shaun A | | #2

      I was thinking this same thing. Is there a good place to get polyiso or just go to the big box store? Lowes around me I believe doesn't have any polyiso or nothing comes up when I search for it. Home Depot has an R-Tech brand 1.5" faced on both sides for $17/sheet. I get confused easily when it comes to all the different foam boards. I also have a bunch of Intello Plus left over that I can use on the interior walls and ceiling. I am in climate zone 5A.

      1. fast_cheap_mediocre | | #3

        My local lumberyards carry polyiso in several thicknesses. I’m in Maine.

        1. Shaun A | | #5

          Thanks I will check it out!

      2. Stephen Sheehy | | #6

        Check out Craig's List Maine for reclaimed polyiso.

  2. Jon R | | #4

    Around here (SE Michigan), I see much better $/R prices on unfaced EPS than polyiso. Even before properly de-rating polyiso when used on the exterior. Then there is the better moisture performance of plywood+EPS (it allows more inward and outward drying).

  3. Cody Sibell | | #7

    Consider regular OSB and a peel-and-stick WRB like BlueSkin. Easier to get right than regular house-wrap and removes the necessity to tape seams on either the OSB or the housewrap. I bet this combo will be much cheaper than ZIP and have at least as good performance. Throw unfaced EPS (or polyiso) over that and you should be set. It's not that much extra labor to go belt-and-suspenders and tape the seams of the OSB and the rigid foam for absolute peace-of-mind, but if cost is of utmost concern, the peel-and-stick alone should be sufficient.

    Beware of no-name polyiso for exterior walls - its performance can drop off substantially below freezing. It's not necessarily a huge deal unless in your climate you need to maintain a certain r-value to prevent condensation on the sheathing. Dow/Dupont Thermax is tested to maintain r-value - the doesn't mean it's the only such product, but it's the only one I've seen any published data on. Any lumber yard/construction supply company will be able to order specific insulation board - don't confine yourself to the prices/products on the shelf at home-depot. If you use foil-faced polyiso on the exterior, make sure you maintain drying potential to the interior - no vinyl wallpaper for example.

  4. Arnold K | | #8

    I had planned on using Zip sheathing for my house build but it being almost twice the cost at the moment in my area, I am going with plywood and WRB like Tyvek.
    Labour isn't much of a concern in my case since I am building the house but even with labour, it's still cheaper.

    Arnold

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