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Old 08-17-2010, 06:10 PM   #1
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When cutting ceiling joists, how thick should the header be?


Say I wanted an 8'x4' open section in my ceiling, like the picture below but bigger

How would I determine the thickness of the necessary joists and headers? In the diagram, they just doubled up the joists and header. What about for larger openings though? Is there a calculation for this?


Thanks in advance,
Dan
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Last edited by dwoloz; 08-17-2010 at 06:23 PM.
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Old 08-17-2010, 06:17 PM   #2
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When cutting ceiling joists, how thick should the header be?


There is no picture.
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Old 08-17-2010, 06:25 PM   #3
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When cutting ceiling joists, how thick should the header be?


Whoops, sorry, should be visible now
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Old 08-17-2010, 08:45 PM   #4
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When cutting ceiling joists, how thick should the header be?


It would help if you stated the reason for the opening. Structural design is based on use and load.
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Old 08-17-2010, 09:26 PM   #5
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When cutting ceiling joists, how thick should the header be?


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It would help if you stated the reason for the opening. Structural design is based on use and load.
Ron
Sorry for the vagueness. I'd like to open up a section of my ceiling, of which I don't yet know the size, to let light into the room below and provide ladder access to a sleeping loft above
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Old 08-18-2010, 07:03 AM   #6
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When cutting ceiling joists, how thick should the header be?


I think you should get an opinion from an engineer.As Ron says rafters are designed based on use and load.You propose changing both.Your rafters were probably designed to transfer load not support load.Is the picture cutting floor joists or rafters?

Last edited by daveb1; 08-18-2010 at 07:10 AM.
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Old 08-18-2010, 07:03 AM   #7
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When cutting ceiling joists, how thick should the header be?


Quote:
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Sorry for the vagueness. I'd like to open up a section of my ceiling, of which I don't yet know the size, to let light into the room below and provide ladder access to a sleeping loft above
You need to have this structural situation designed by a professional who has onsite familiarity with the issues. You live in an earthquake zone with live loads above. Wouldn't a window or skylights work? This seems an odd and complex way to light up a space.
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Old 08-18-2010, 02:49 PM   #8
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When cutting ceiling joists, how thick should the header be?


The OP's picture is a dead ringer of pull down attic stairway. If you don't do the engineer request as mentioned, at the very least post a pic from up where you want to cut into.
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Old 08-19-2010, 12:44 AM   #9
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When cutting ceiling joists, how thick should the header be?


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You need to have this structural situation designed by a professional who has onsite familiarity with the issues. You live in an earthquake zone with live loads above. Wouldn't a window or skylights work? This seems an odd and complex way to light up a space.
Ron
I'm attempting to create a new bedroom by using a small portion of a 500sqft bedroom. This new bedroom would have a very small floorplan utilizing mostly vertical space. To make that room feel less clostrophobic, get light in and create access to the sleeping loft, I'd like to open a portion of the ceiling

I was wondering if there was some steadfast calculation for this kind of thing. ie max size of opening or how much timber to use for an opening, etc

I would very much like to hire a structural engineer but at least for now, I just don't have the cash. I had one over to give an estimate and he seemed confident it was feasible but quoted 1500-2000 dollars
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Old 08-19-2010, 07:22 AM   #10
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When cutting ceiling joists, how thick should the header be?


You're getting the same advice here as you got in your thread 'looking to utilize attic space'.You also expressed concerns in that thread about the existing rafter framing.I really think you should pay for a qualified on site appraissal.
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Old 08-19-2010, 07:45 AM   #11
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When cutting ceiling joists, how thick should the header be?


Quote:
Originally Posted by dwoloz View Post
I'm attempting to create a new bedroom by using a small portion of a 500sqft bedroom. This new bedroom would have a very small floorplan utilizing mostly vertical space. To make that room feel less clostrophobic, get light in and create access to the sleeping loft, I'd like to open a portion of the ceiling

I was wondering if there was some steadfast calculation for this kind of thing. ie max size of opening or how much timber to use for an opening, etc

I would very much like to hire a structural engineer but at least for now, I just don't have the cash. I had one over to give an estimate and he seemed confident it was feasible but quoted 1500-2000 dollars
There is no, "steadfast calculation" It is specific(unique) to both the location and the structure.
How many people in how many threads have to explain this to you before this becomes clear to you?
This is my last post on this.
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Old 08-20-2010, 03:58 PM   #12
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When cutting ceiling joists, how thick should the header be?


Looks like you could do something like this but first support the joists from the floor below before cutting.
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Last edited by eastside; 08-20-2010 at 04:01 PM.
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