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Community and Q&A

Does this roof assembly work?

Jayne_Torres | Posted in General Questions on

I’m building a steel-framed tiny house on wheels.

The envelope is a 10’x28′ rectangle.  The roof is a slightly pitched shed style from one long side to the opposite long side.

I’m trying to keep the roof assembly as thin and as lightweight as possible, yet, of course,  maintain structural integrity and insulation properties.  

Will this work: (bottom-up)
1″ R-Max 3 directly on top of the framing 
Building paper
9/16″ verco dek ing

Then I’ll put 3″ R Max in the framing cavities on the inside.

Yes?  No?  Any suggestions??

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  1. GBA Editor
    Brian Pontolilo | | #1

    Hi Jayne,

    Where will the house be located? Why do you want to use steel decking? What type of roofing do you plan to use?

  2. Jayne_Torres | | #2

    Hi Brian,

    The house in in CZ 3 in the San Fran north bay area. Wine country. Mild.

    I had an architect do the plans. His spec for the roof/ceiling assembly is as follows (from inside to outside):

    1/2"Gypboard (minimim)
    3 1/2" framing with insulation between joists
    9/16" shallow verco decking (26g)
    1" (minimum) thick rigid insulation
    waterproof membrane underlayment (Acrymax?)

    I'm a bit skeptical about the rigid insulation on top of the decking although it is done, but usually with a metal (or whatever) roofing material on TOP of it. So, basically I thought I'd reverse the order and place the insulation UNDER the decking and let the decking be the roof. I don't know why the architect spec'd the verco decking and he has rendered himself unavailable for questions and consult. I am not wedded to either of these plans. All suggestions and recommendations welcome!!!

    Again, I thank you and this site for all the information you gather and provide!! Wish I had joined sooner in this journey.

  3. Jayne_Torres | | #3

    Hello. Jayne, here. I just received an email saying there has been a comment to my reply to Brian above, yet I don't see it here. Please resend??

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