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Community and Q&A

When is wall blocking required?

Alex Halpern | Posted in Building Code Questions on

Hi, I am working on a tiny house that has 10 foot walls, 24 on center spacing. 

The wall sheathing is run horizontally and there is currently no blocking in the walls along the horizontal seems.  However, I did install a bunch of diagonal metal strapping for additional bracing strength. 

After some research I am concerned about not having any blocking, especially along horizontal sheathing seams that are only fastened every 24 inches vertically. I did nail every 4 to 6 inches though.

The house wrap is up and I’m ready for siding. It will be somewhat of a pain to add in blocking now. But if it is important I want to add it in. Since it is a large tiny house on wheels that will be bouncing down the highway, I want to make sure I’ve covered all my bases structurally.

Any thoughts on if it would be strongly recommended, or not necessary to add the blocking?
This would be greatly appreciated.

Thanks ,

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  1. Expert Member
    Zephyr7 | | #1

    The primary purpose of horizontal blocking in regular houses is to act as fire stops to limit vertical fire spread in walls. I suppose it would serve the same purpose in tiny house, but I don’t think the same codes apply.

    Horizontal blocking also provides a little additional rigidity but that’s not it’s primary purpose. What popped into my head is that some 1/8” hardboard sheathing on the exterior of your studs would add a LOT of rigidity for starting and stopping while driving (racking resistance) with minimal weight and dimensional increase. This is often how bookcases are assembled. If you go this route, you need to use a good number of fasteners, as in about a foot or less apart on every framing member including the top and sill plates.


  2. Trevor Lambert | | #2

    Strategically placed blocking is also important for attachment of things like cabinets and handrails, especially with 24" spacing.

  3. Mike Theis | | #3

    Put the blocking in and nail through the house wrap. Than tape over the nails.

  4. Expert Member
    Malcolm Taylor | | #4


    Structural blocking has two main purposes. it can provide rigidity at mid-span for tall walls (in our code anything over 10'-0"), and it increases resistance to shear forces by providing a fastening surface for all edges of sheathing panels (required only in high seismic zones).

    I would only worry about the blocking if you had walls with a lot of opening in them. Otherwise, the sheathing is it is is probably fine.

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