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Community and Q&A

Ceiling service cavity

user-1137156 | Posted in Energy Efficiency and Durability on

I’m sold on having a service cavity. In the walls, it’s easy to see how to implement one with double stud walls but. However the ceiling is not so apparent. Is it easier to delay building interior partitions till after the trusses are in place and the air barrier material installed on their bottoms? Should the interior partitions be the same height as the exterior walls or only to the bottom of the cavity? Is there a “preferred method of attaching the “ceiling joists”?

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  1. HD_DIY | | #1

    The service cavity, is that for running additional electrical, etc...later on down the line? If that is the case , open cavities can be an issue in terms of fire blocking. Typically long horizontal or vertical runs behind walls need to be sealed.

  2. user-1137156 | | #2

    I just happened to find Thorsten Chulup's (sp?) method an it sounds like the best way to go. Basically it is buld all the interior partitions to reach the top of final ceiling drywall. Then add enough temporary walls to support the ceiling joist system planed. Then install the joist (running across the trusses) then install OSB, nailed from the top. Then add a layer of house wrap & set the trusses. After adding screws from below into the bottom chords of the trusses the "temporary walls are recycled.

  3. user-1137156 | | #3

    After looking at my floor plan and the need for temporary walls to use Thorsten's method, I've switched from a 2x4 ceiling cavity to 2x6 16" OC as this will eliminate any need for temporary walls and any need to support the ceiling from the trusses. (I will need #1 dense or select structural over one room but otherwise #2 lumber is adequate.) I'm sure the slight added cost of the 2x6's will be more than offset by the labor saving of eliminating any need for temporary walls.

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