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Nail Fin Window Install – What is “Cross-blocking”?

idahobuild | Posted in General Questions on

Hello,

Can someone explain what “cross-blocking” is as it relates to the installation of windows?  In our build most of the windows are casement.  Is it just making sure that shims/screws/nails are in the designated locations?

Thanks. 

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Replies

  1. Malcolm_Taylor | | #1

    idahobuild,

    Cross blocking are the blocks you put on the hinge side of a door or casement window near the bottom, and the opening side near the top, to help counteract the loads the operable portion exerts.

    1. cs55 | | #2

      are there any reasonable retrofit options to help with this?

      1. Malcolm_Taylor | | #5

        cs55,

        First identify if the absence of blocking is causing problems. Most doors and casement windows are secured sufficiently by their fasteners, and foamed into place. They don't often need more than that.

        1. cs55 | | #6

          after re-reading everything, i think i misunderstood.

          https://i.imgur.com/sNAadZ7.jpeg

          i was thinking this, but for walls.

          reason for asking: have 36x84 tilt and turn windows, 10' walls, 16" oc framing. theres only 2 vertical studs on each side of the window . the windows don't have to be slammed at all for the walls to shake lmao.

          i never open the windows so its not a big issue. just curious.

          1. Malcolm_Taylor | | #7

            Up here our code would require mid-span blocking for the 10ft studs but I don't think that would make much difference. There doesn't seem to be any requirements to limit the noise or vibration from operable doors or windows - which can be annoying.

  2. idahobuild | | #3

    Okay. Is the blocking 2× at those locations (blue lines)? Right now each widow RO has two studs either side and well be addig 2x bucking the full depth of the wall (red lines in atch'd pic). Between most windows we have double that and no real room for blocking. Would it be necessary at those locations?

    1. Malcolm_Taylor | | #4

      idahobuild,

      By blocking they mean shims between the RO and window frame. You don't need to do any remedial framing, it's just to take the lateral loads off the nailing fin.

  3. idahobuild | | #8

    Thanks Malcolm.

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