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Community and Q&A

Strapping material for rainscreen…plywood fir or spruce?

unclejemima | Posted in General Questions on

I’m ready to put the strapping on-top of my WRB, only I’m not sure what the best choice is.

I want a 3/8″ gap, so cutting plywood strips is my only option (there is NO composite furring strips available in town…I called everywhere!)

I’ve got the option of 3/8 spruce with exterior glue, or 3/8 fur with exterior glue.

Does either have a lower tannin content that may deteriorate the WRB? Do I even have to worry about that? Should I back prime the strapping to avoid this?

I’m going to put cement board over the strapping then stone.


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  1. brp_nh | | #1

    Cor-A-Vent Sturdi-Strips (3/8" deep) are available from ABC Supply Co. if you can't buy from a local supplier. Their website doesn't look good, but they are legit:

    We used these with the SV-3 product for a vented rain screen on our house.

  2. Expert Member

    Mark, As far as I know Tyvek was the only WRB which had problems with deterioration due to cedar tannins, and they have since reformulated their product to address this.

  3. GBA Editor
    Martin Holladay | | #3

    Either spruce or fir will work fine. But I wouldn't use the fur if I were you.

  4. mtr7982 | | #4


    The Native Americans, the original fur rainscreen , I believe they turned the fur in which would've prevented thermal bridging to the tee pee support poles. Hmmm you have my wheels turning.

  5. unclejemima | | #5

    Thanks guys :-)

    Brian, thanks for the link. I'm in Canada so the weak CAD, shipping and Duties would kill me :-(

    Malcom. Good to know. I won't worry then.

    Martin, I'll use the fir. Its difficult to find exterior glue rated 3/8" plywood, but I did find the exterior rated glue and fir for a reasonable price. 99% are interior glue and usually spruce.

    Mr Miller...interesting reply :-)

    Thanks all!

  6. GBA Editor
    Andy Engel | | #6

    I used mason's lath. I suspect it was poplar, but it's cheap and 3/8 in. thick.

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