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Installing T&G tight knot cedar 1×6 on a SIPS vaulted ceiling

user-31766 | Posted in General Questions on

I plan to install 1 x 6 T&G tight knot cedar on the vaulted ceiling of my SIPS house. If I use a 2 x 4 furring system between the cedar and the OSB, will I be building in a moisture condensation issue? I will not be installing drywall on the ceiling as the OSB is taped on all panel seams. The 2 x 4’s will function as chases for electrical wiring for the surface mounted lights and Big Ass ceiling fan.

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  1. Expert Member
    Michael Maines | | #1

    That should be fine. Everything on the interior side of the OSB will be at a similar temperature and moisture level.

    1. user-31766 | | #2

      Thanks Michael! I was suddenly overwhelmed with the thought of condensation...And just now discovered the BS+Beer discussion on vapor with Christine Williamson. Have a great day! Paul

  2. Expert Member


    It's also a perfect depth cavity for ceiling fan mounting boxes.

  3. stevetracympls | | #4

    I agree there should be no issue with condensation. If you haven’t already, I would recommend verifying with the SIPs manufacturer the anchoring for the ceiling fan. If there is not blocking or lumber in the panel, you are only anchoring into osb which may not hold over time with the weight/dynamic forces introduced by a ceiling fan. I realize this isn’t your question and only bring it up since I have run into this issue in the past.

    1. user-31766 | | #5

      Thanks Steve! I have been researching fasteners that have load testing data made for OSB specifically. I met with my client this weekend and we decided to attach the fan to the 5.5" x 21" Glulam beam, hiding the electrical with a small piece of DF trim.

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