Installing multiple patio doors.

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  #1  
Old 03-07-14, 08:12 PM
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Installing multiple patio doors.

We are replacing an entire wall of porch windows with four sliding patio doors (6ft).

The lumber yard calculated the headers. Due to low ceilings we will be using two 7.25 lvl's per door.

I assume I will need two jack studs per side but do I need two king studs between the doors?

We would be looking at 9" between each door. I am trying to get them as close as possible.


It's a two story house but the porch is only 8 feet deep.
 
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Old 03-07-14, 09:38 PM
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You should update your location since it can affect the advice given. The answer also depends on where you live and what code the inspectors in your municipality go by, which we are probably not privy to. (IBC? IRC?) We would also need to know more information about your house. We assume the ceiling joists are perpendicular to this wall. Two story house but you say this is a porch? Is it a shed roof addtion? Snow load? Roof pitch? How far from this wall to the next load bearing wall or to the opposite exterior wall? Center bearing floor or clear span floor? An exterior picture might help us understand the construction of this part of the house.

Not least of all, will this be inspected? If so, why not call your building department?
 
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Old 03-08-14, 03:36 AM
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The house is a cape. At some point they added a full dormer to the front and back if the second floor. The area that I am calling the porch is within the foot print of the original house. It span stage entire width of the house. It is the back wall supporting two floors and the roof load. The joists are perpendicular. There is 8 feet to the next wall. I was told we need to plan for a 50lb per sq foot snow load.

I do not know what they follow for code. The offices are closed on Fridays.

And I am in Mass.
 
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Old 03-08-14, 06:05 AM
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Your headers would have been stronger if you bumped them up to 2x10's and cut out the bottom member of your double top plate, assuming that's what will rest on top of your header. I would suggest you look into that if it's not too late.

I think it would be safe to assume that each header needs its own king stud and that you will want 2 trimmers per header, for a total of 9" of framing between your 6ft openings. -IBC table 2308.9.5 and IRC table R502.5(1)

By next wall, I mean the next wall that is load bearing, either the opposite exterior wall on the other side of the house... in which case you would tell us the width of the house... or one in the center of the house that is supported to the foundation (you'd look for supporting walls or beams in the basement to identify this wall).

Back to the king studs, there may be another factor that is a little hard for us to determine, and that is your local wind load requirements... something else we do not know. Putting four 6' doors together is removing an awful lot of your load bearing wall, which creates a weakness in the wall- it means you no longer have a solid wall of studs that are 16" on center that can all act together to resist wind load. Since your king studs run continuously from top plate to bottom plate, they are what resist lateral forces (+ / - wind load) and so I CERTAINLY would not install just one king stud between headers unless you want your walls to snap and house to collapse during the next "Sandy" or nor'easter. This may be something that you want to run past a structural engineer just to make sure that you are not compromising the strength of the wall. The space between door openings is basically a "narrow wall", and depending on your wind load, it may be that he says you need to have 3 king studs between each opening for lateral strength... or that the distance between headers must be a minimum of 16" to act as a shear panel and to serve as an anchor to resist uplift. This is the sort of thing that is cloudy at best when interpreting code and much of it falls on a structural engineer to calculate all the factors involved... plus the code enforcement officer who performs the inspection may have another opinion.
 
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Old 03-08-14, 12:22 PM
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I agree with Brant's comments completely. However the only thing addressed is vertical weight. Unless horizontal movement is taken into consideration it may not be a good idea. I was asked to replace doors similar to your situation. The walls had minimal mull between the existing units. The walls would shake with the slightest push. This indicated too little support between the units.
I would at a very minimum get the blessings of a structural engineer and the permit department.
 
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Old 03-09-14, 06:12 PM
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Thanks,
The wall was made up if single pane window panels between posts that were 9 feet apart with a single rough cut 2x8 for a header.

I am sure that even if I went with singles it would be stronger than what was there but it has the be up to code.
 
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