Max door size for load bearing wall

[thetruck454]

I have a cross gable addition 24' x 40' being added to my garage using scissor trusses spanning the 40'. Garage doors are going in the 24' load bearing wall. I had an idea of two 10'x10' doors (Already have a 9'x8' door in one of the bays in the current garage and it limits me in what I can put in that bay) but I'm not sure I can remove that much of the load bearing wall. It's going to be a two bay garage so if I can help it I'd like to stay with two doors because I feel a single door wastes space in the front of the garage and then I'd have to span even more of the load bearing wall with a single 16' or 18' door. Does any one know of any online calculators or can point me in the right direction to figure out if it can be done and if so how big of a header above the doors I need?

 

[signcrafter]

You can open up as much of the wall as you want with the right header up there. You shouldn't have any issues with single doors. A 10 foot span isn't that big of a deal. The exact specs will depend on a few things like roof loads and footings and what not. But to answer your question a couple 10' wide doors aren't a big deal.

 

[Innovate1]

If you have the truss specs it will give the max load at each end. From there you can put that loading in at 2' intervals (or if number of loads is limited like on a program I use from WWPA you can convert to a distributed load). Or you could look up the required design loads for your area and use that. WWPA (western wood products association) has a free calculator that will give you the needed sizes. Very handy for beam, joist and post loading.

If you go with two 10' doors that only leaves 4' total width of walls between doors to resist racking sideways. Look up "portal framing" for details on how to reinforce the wall against that. Pretty sure that is below code width for the remaining sections but it also depends on how high the walls are.

 

[WNYflyer]

If you have the truss specs it will give the max load at each end. From there you can put that loading in at 2' intervals (or if number of loads is limited like on a program I use from WWPA you can convert to a distributed load). Or you could look up the required design loads for your area and use that. WWPA (western wood products association) has a free calculator that will give you the needed sizes. Very handy for beam, joist and post loading.

If you go with two 10' doors that only leaves 4' total width of walls between doors to resist racking sideways. Look up "portal framing" for details on how to reinforce the wall against that. Pretty sure that is below code width for the remaining sections but it also depends on how high the walls are.

As stated by Innovate1, you need to get a handle on how much of the wall may need to remain to act as a "shear wall" or in lieu of a "shear wall" some kind of system to replicate it. That wall needs to be stable in the direction parallel to it's length by some means such as wood "shear wall", steel portal frames, Simpson Strong-Wall, etc.

The header can be easily designed but being able to tear up the wall that much with openings will take more thought from a stability/racking standpoint.

 

[signcrafter]

If you have the truss specs it will give the max load at each end. From there you can put that loading in at 2' intervals (or if number of loads is limited like on a program I use from WWPA you can convert to a distributed load). Or you could look up the required design loads for your area and use that. WWPA (western wood products association) has a free calculator that will give you the needed sizes. Very handy for beam, joist and post loading.

If you go with two 10' doors that only leaves 4' total width of walls between doors to resist racking sideways. Look up "portal framing" for details on how to reinforce the wall against that. Pretty sure that is below code width for the remaining sections but it also depends on how high the walls are.

I didn't even think about sheer of that wall. But yes with only 4' of wall besides garage openings you are going to have issues. You will need to talk to someone like an engineer about this because you are basically going to have a 18" wall then 10' door then 1' wall then 10' door and then 18" wall to corner. Or some other variation of small numbers for the walls. They do make special systems for situations similar to this but it's going to have to be designed most likely and not going to be cheap if it's even possible. Simpson strong wall is one type of system to look into.

Sorry about my first post I hadn't had my second cup of coffee yet and missed the part about no shear walls with those big of doors.

 

[kbs2244]

If it an addition can he use the existing wall as a shear wall?

 

[Innovate1]

I would think so if is attached such that the existing structure prevents racking. Probably but not knowing the details it's hard to know for sure.

 

[thetruck454]

I would think so if is attached such that the existing structure prevents racking. Probably but not knowing the details it's hard to know for sure.

The garage that it's attached to is a 30'x40' that is trussed partially with attic trusses and partially with normal trusses and uses 2x6's for wall construction. The 30' gable end of the existing garage has a 9' &15' door. The addition will attach to the 40' side.

I've attached a picture of where the addition will attach. Obviously the shed will have to be moved. Also need to move the electrical meter, just not sure the best way logistically to minimize the time the house is without power.

 

[YukonXL04]

My engineers allowed me to do a single 20ft door on a 24ft wall, 2 ft on either side. Portal wall framing for sure.
New garage has a 9ft door on a 12ft wall.

You just need to get with an engineer and see what they think and what they will sign off on.