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Discussion Starter · #1 ·
This is a 32" door that I want to expand into a 64" archway. As you can see from the photo, the top of the doorway is built like a header - it's a plywood sandwich - but it's only built with 2x4s. This is the centerline wall (i.e. directly under and parallel to the roof ridge) for a one story house. The attic has a finished floor so I can't see anything up there at this point, but it's a truss roof. Is that code for any load bearing header, even one as short as a doorway? As you can see the cripple studs, or at least one of them, is not even resting on the header. I'm trying to figure out how much trouble I need to go to. (If I treat it as load bearing, I'm not going to do a bunch of calculations to save 50 cents in wood, I'm just going to install 2x12s over 2 jack studs.)


Furniture Door Fixture Wood Handle
Brown Door Wood Window Rectangle
Brown Table Wood Rectangle Plank
 

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retired framer
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Well like I said looking above is very problematic. I will still look in the crawlspace.
Looking at the joists above the drywall maybe.
Do they join over the wall or pass right over, or do they run the same direction as this wall?
 

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Looking now won't tell you anything. You should remove at least 6" of ceiling and try to see what kind of truss. If you have finished flooring above, is it a truss that allows a room in the middle? Anyway, if load supporting, you may have to add a footing or make sure wider load is supported by the house structure.
I don't know about truss. Find out all you can about the truss you have and structure of the space above then that will tell you a lot about what kind of load support the framing below needs to do. Figure out what kind of truss you have then ask.


Image shows truss roof with room. Floor joist is joined in the middle. I don't know if that kind of floor will need support. 2x4 header does not seem to tell much since trusses seem to be spaced 24" too. Just guessing.
 

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If the wall is extends under all the trusses, it could be a load bearing wall, even with that small header. Not typical, but possible.

I can tell you that the bending load on span with a uniform load increases by the square of the length of the span - so double the span = 4 times the bending 'force' (engineers call that "moment", which is similar to torque). The good news is that the capacity of the beam also increases with the square of the depth, so double the depth = 4 times the bending capacity (for a solid rectangular section of the same material, such as 2x lumber of the same grade). That means since you're doubling the span, the header only needs to be double the depth (2x8s), not 3 times (2x12s), to have the same capacity as the existing.
 

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If you are going to make the door larger you will be putting in a new header anyway so I would just put in a load bearing header. I would say the evidence says it is load bearing, but with attic above they may not consider any live load. Thus a small header for a short opening. It does look like there may be two top plates in the picture also indication of a bearing wall. easy to break a little hole to see if there is. However some framers do put two top plates on all walls bearing or not.
Funny, there is never enough time to do things right. but there is always enough time to do it over again.
 

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Naildriver
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How tall with the apex of your arch be in relation to the existing wall? I'll ask the simple questions.
 

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Discussion Starter · #16 ·
Single top plate. "Header" is there to carry the cripples above, and a place to nail the door trim.
Yes I'm pretty sure it's a single top plate, but my question would be, why did anyone go to the trouble of building a plywood sandwich for something so simple? If I frame a simple door I just put the studs cross ways.
 

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Yes I'm pretty sure it's a single top plate, but my question would be, why did anyone go to the trouble of building a plywood sandwich for something so simple? If I frame a simple door I just put the studs cross ways.
The plywood sandwich is the customary way of building a header. The reason it is constructed of a 2x4's instead of 2x10 or 2x12, is because it is NOT a load bearing wall. The header is just a cross member to support the vertical load, but also a spacer for drywall and door trim. The 1/2” plywood is just a part of the spacer to make two 2x's as wide as a 2x4.
 

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Yes I'm pretty sure it's a single top plate, but my question would be, why did anyone go to the trouble of building a plywood sandwich for something so simple? If I frame a simple door I just put the studs cross ways.
I was thinking along the same lines. I don't really know. One flat 2x4 across the top of the opening would seem sufficient, if it's not carrying any load, but maybe what you have is the 'standard' way to do it. It seems possible, at least to me, that the built up header was used because there is some load from above being carried. Not knowing for sure, I would sandwich a piece (or some scraps) of 7/16" OSB between a couple 2x8s and put it in as a header, just in case.
 

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retired framer
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I was thinking along the same lines. I don't really know. One flat 2x4 across the top of the opening would seem sufficient, if it's not carrying any load, but maybe what you have is the 'standard' way to do it. It seems possible, at least to me, that the built up header was used because there is some load from above being carried. Not knowing for sure, I would sandwich a piece (or some scraps) of 7/16" OSB between a couple 2x8s and put it in as a header, just in case.
A double 2x8 with 2 jacks studs under each end to cover any load that might be carried, if you put a 2x4 sill below that for drywall, no need for plywood or glue. 3 nails 16" on center for the header.
 

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retired framer
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I was thinking along the same lines. I don't really know. One flat 2x4 across the top of the opening would seem sufficient, if it's not carrying any load, but maybe what you have is the 'standard' way to do it. It seems possible, at least to me, that the built up header was used because there is some load from above being carried. Not knowing for sure, I would sandwich a piece (or some scraps) of 7/16" OSB between a couple 2x8s and put it in as a header, just in case.
When the less experienced are building house and plan for a stick built roof, don't know exactly were there might be point loads, so they put headers in every door. It is likely nothing but replacing it with a header instead ripping the house apart is the quick and easy.
 
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