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Second Storey Window

p_550spyder | Posted in General Questions on

I posted a question a while back regarding enlarging a window on my main floor (window is in my living room). Now I’m back asking a second question, this regarding enlarging another window in my house. This one is on the second floor (master bedroom) and same as my original question is on the gable end wall of my house, which isn’t bearing any load. Above it is my attic, so only the gable portion sits above the wall as the joists in the attic run parallel. 
Currently, I have two windows in my master bedroom, they measure 65″ high x 32″ wide. A centre wall sits between the two windows that measure 56″ wide. I’m planning to turn the two windows into one large window that will measure, 65″ high x 120″ wide (10 foot span). Since I’ve already torn out the wall, I’ve discovered the spacing above the windows to the top plate measurement is 7.5/8″ high. From my research, for a 10′ span window opening the suggested header size is 10″ in height. I’m wondering if that’s definitely the case for a wall that doesn’t have a true load it’s bearing? Would a double header that is 8″ in height be sufficient without the fear of any sag developing over time or is this a case where I should consider using an LVL for at least 1 of the two header pieces? Appreciate any advice that can be shared. 

Thank you,

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  1. Expert Member


    If the gable roof above is not supported by that wall, then the same conditions and advice apply as did in your previous question - and no lintel is required.

    1. p_550spyder | | #3

      Hi Malcolm,

      So, in other words, I'm safe to use 7.5"/ 8" high sawn lumber, with a window opening span of 10' wide and I shouldn't have any issues? Just want to make sure before I move forward on the work, especially since the span is large. I don't want there to be issue of warping or sag for that width, even though there is no real significant weight above it. Seems as though the recommended findings is for 10" high, so it's why i'm a little unsure and double checking here.

      1. Expert Member
        MALCOLM TAYLOR | | #4


        Where did the 10" header size come from? Was it for load-bearing walls?

        If the wall is not load-bearing, the sheathing will provide sufficient vertical support. What an opening of that width benefits from is lateral resistance. So rather than using any header, I would use several top-plates to act against wind loading.

        All this advice comes from a practical perspective. I don't know what the code where you are says about openings like this.

        1. p_550spyder | | #5

          It's from my research online, seems to be consistent that 10" height is the recommended size for 10' opening but most don't necessarily specify if it's also factoring load bearing walls etc. Not sure if one is just to assume such?

          As for lateral resistance, your suggestion on using several top plates does seem practical as well as logical for sure. Further to your point, I could also make the two adjacent walls and portion beneath the window shear walls, by nailing 1/2" plywood, apply the proper nail size and schedule for extra added shear resistance. Might seem like overdoing it, but certainly would be laterally stronger.

          1. Expert Member
            MALCOLM TAYLOR | | #6


            Beyond general information - like you don't need headers in non load-bearing walls - I'm a bit reticent to give detailed structural advice because there can be all sorts of things I can't see from here.

            The two areas that are subject to lateral forces are the sill and head of the opening. If I were doing it, I'd double the plates at both locations, and maybe sandwich a layer of 5/8" plywood in between.

  2. nynick | | #2

    I don't care. I want to see a picture of that 550. ; )

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