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Community and Q&A

shiplap ceiling

Ryan_Mount1 | Posted in General Questions on

Hi everyone, 

Just wondering if there is a consensus on whether or not drywall is required behind a ship lap ceiling.   Above the ship lap would be strapping, then poly which is my air barrier that was installed before interior walls and sealed, followed by blown in cellulose.  I’ve tried to minimize punctures in the poly as much as possible and will be taping it up as best I can before insulation/finished ceiling.  

Another cheaper option than finished drywall would be 3/8 plywood with seems taped, then my ship lap would go on that. Plywood would be somewhat difficult to seal to electrical boxes, bath fans etc.  in a meaningful way.   Seems like this method might be overkill.

Thanks for any input! 

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  1. Expert Member
    Michael Maines | | #1

    Ryan, the answer depends on your overall goals, climate zone, and assembly details. In any case, somewhere in your assembly you need at least one good air control layer, and one vapor retarding layer. They can both be the same material but they don't have to be. What are your goals, climate zone, and assembly details?

    1. Ryan_Mount1 | | #3

      Hi Michael,

      I'm in climate zone 6. It can get pretty cold here in the winter.

      My goal is just to build a very comfortable house. Energy efficiency somewhat goes hand in hand with that goal. The ceiling assembly will be the shiplap on strapping, poly, then r60 cellulose in a vented attic. The poly would be both air and vapour barriers.

  2. Expert Member


    If you are going to put poly up in either case and the question is where it is enough, or needs drywall before the wood ceiling, my experience is the the poly works fine as an air-barrier on its own.

    1. Ryan_Mount1 | | #4

      Hi Malcolm,

      Thanks for the input! I'm leaning that way as well. I've been trying to seal it up tight again after the electricians were a little sloppy with their knives.

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