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Using rips of ZIP Sheathing for furring over 4 inches of rigid foam

RussMill | Posted in General Questions on

Anyone have any concerns using 7/16 zip sheathing rips for rainscreen furring??
I thought it would NOT be stiff enough…??

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  1. NateSc | | #1

    OSB is crappy to nail or screw into. Allowed in the code, but in a couple years siding will start pulling loose. 1x4 eastern white pine has really good bite.

  2. Jon_R | | #2

    RockWool recommends using 1x3 treated wood furring and I'd guess that the principle applies to any rainscreen. Thinner and OSB seems like a step in the opposite direction.

    1. RussMill | | #4

      Thats how it felt for me as well. I have used advantech 3/4 subfloor rips for furring. It is tough stuff! $30/sheet too!

      The problem we have is getting 1x4 pine is expensive! No one carries a "furring" grade. Either clear or junk cand canes.

      Plywood has gotten SO BAD with delamination that i wont use it.

  3. Expert Member
    Deleted | | #3


  4. Expert Member
    BILL WICHERS | | #5

    OSB in thin strips tends to be more flexible than regular lumber, so you might have it bow out if you don't use extra fasteners.

    Maybe you can get some thin pieces of LVL? That stuff is much tougher than regular plywood, but I don't know if it's available in things smaller than the larger 2x dimensional sizes used for headers and the other usual applications for LVLs.


  5. MattJF | | #6

    Advantech is probably the best of the options for anything that is glued together. Its wet performance seems very good and I expect it is a better option than zip, which is designed to not have edges exposed. Advantech is rated for short term water exposure.

    For 1x look up any saw mills in the area and see what they produce. Some of them run tons of 1x rough pine, which would be perfect.

  6. thrifttrust | | #7

    Nominal 3/4" plywood sheathing is cheaper than 7/16 Zip.

    1. RussMill | | #12

      Not for me, i can buy 4x10 Zip CHEAPER than 15/32 plywood. Screwed up huh!!

  7. hughw | | #8

    We've also been looking for a 1/2" furring strip which would make it easier to meet some dimensional requirements with the window projection we have. Also, will need to be 3-1/2" wide to allow nailing at joints in horizontal boards so nails are not to close to the end of a board. Was thinking of ripping pressure treated plywood which is rated for ground contact. What say you all for it holding up without delamination as rainscreen furring?

  8. Robert Opaluch | | #9

    I was thinking about pressure treated ply too, but ratings of products on Home Depot site were negative. Maybe paint or sealer would improve plywood performance enough?

  9. Expert Member
    Peter Engle | | #10

    All of the PT ply I've worked with has come to the site pretty wet and nasty. You wouldn't want to paint it. At 1/2", you can probably nail it down flat OK, but it won't be fun. You will also want to use SS or HD galvanized nails because of corrosion.

  10. NateSc | | #11

    If you live where there are trees, find a local saw mill. I can't speak for the whole country but in most wooded areas I know you can get softwood species for .50 cents a board foot - cheaper than OSB or plywood.

    1/2 furring is another bad idea, there is not enough bite for the siding and the structural screws will be another issue.

    PT is a waste of money.

  11. Jon_R | | #13

    My experience (different application) with treated 3 play, 1/2" plywood was terrible. Then I tried a different make of treated 5/8" 5 ply and it was great. My backup plan was Advantech.

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