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enter image description here I have a "1.5" car garage with a single slope roof about 12ft high on the taller end. All of the walls are 2x4 framing with a double top plate. I would like to install a 48x48 windows in the taller, load bearing wall. It looks like I'll need to cut into 3 existing studs to frame out the window.

My plan was to install 2 new king studs, 2 new jack studs, a double 2x8 header, rough sill and trim 3 existing studs that will become the cripples both above and below the window. enter image description here

I have 2 questions:

  1. Does my framing look correct?
  2. Would it be necessary to built a temporary wall to support the roof if this is all done in 1 day with no snow load? If so, how far from the existing wall can the temp wall be (trying to limit the amount of extra lumber I need to buy)?

Thank you in advance!

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  • What's your design snow load? 1.5 car? Is that 18 ft wide?
    – popham
    Nov 13, 2023 at 4:19
  • @popham I'm not sure, how would I calculate that?
    – Yev
    Nov 13, 2023 at 4:22
  • The design snow load in my city is on the city's website. Search the web for your city's name and design snow load. It'll probably be in the top 3 results.
    – popham
    Nov 13, 2023 at 4:25
  • I can't find anything for mine or neighboring towns, looks like it's a "case study area" The closest town I could find was 30.0 psf
    – Yev
    Nov 13, 2023 at 4:32
  • you might have to move that tie also.
    – Jasen
    Nov 13, 2023 at 4:35

1 Answer 1

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Your single king studs are good based on IRC R602.7.5. Assuming a 50 psf snow load, IRC Table R602.7 indicates that a double 2x6 header with single jack studs is adequate. If you install the double 2x8 header, IRC Table R602.7 indicates that double jack studs are necessary to develop the header's excess strength.

From your image I see 3 cripples, implying 4 16" gaps, implying a 64" width of roof joists without support during construction. Assuming 10 psf dead load (appropriate for roof joists + OSB sheathing + 1 layer of asphalt shingles) and assuming an 18' wide span, that's a total load of (10psf)(5'-4")(9') = 480#. For #2 Spruce top plates, this is 190% of the top plate's strength, so temporary shoring is definitely warranted. For an 18' building width, keep the temporary shoring within 3'-6" of the wall (less than 1/4 of the adjacent span's length, i.e. 3.5' < (18' - 3.5')/4).

A 12 ft wall is unusually tall. I can imagine a designer using that horizontal piece above your window to brace the wall against the roof diaphragm. If that were the case, however, then there would be detailing analogous to a waler beam along the wall to distribute the brace stiffness to other wall studs. I therefore conclude that this horizontal piece's purpose is to stiffen the garage door tracks. The cripple adequately supports this bracing for the garage door track.

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  • Do you know, would the rafter tie (is that what its called) be fine attached to a cripple?
    – Yev
    Nov 13, 2023 at 5:55
  • @Yev, I've updated the answer to reflect my opinion. I believe that horizontal piece is there to stabilize your garage door tracks.
    – popham
    Nov 13, 2023 at 6:11
  • @Yev, I found a moment in time from a YouTube video that shows what I mean by a "waler beam": youtube.com/watch?v=iw2QEoc3GrA&t=3m36s. Your horizontal piece is analogous to the compression brace going across the video's excavation. If you remove the waler, i.e. that I-beam tipped on its side, then the brace would only reinforce a tiny little patch of wall.
    – popham
    Nov 13, 2023 at 6:25
  • @Yev, that's not a rafter tie. A pair of rafters installed without a ceiling exert outward forces against the walls because of the hinge at the roof's ridge. You have no ridge and therefore no hinge, so there's no outward force for rafter ties to resist.
    – popham
    Nov 13, 2023 at 6:29
  • I had also always assumed that it was for the garage door tracks, however, I don't know if you can tell from the photo - the tracks are not actually mounted to it as its too far forward.
    – Yev
    Nov 13, 2023 at 14:52

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