Help With Garage Door Header Sizing

[Jawgarage]

Well, I think I am out of ideas and this is not one I want to guess at in anyway. I know lots about drawing plans, reading plans, and doing framing, electrical, etc. But I am NOT an engineer. I am expanding our 2 car detached garage and adding a second floor with an engineered Truss system. I did not use an architecht. Here is where I am stuck and nervous....

The current garage is framed with 2x4's and we plan on sistering 2x6's to that for added strength. The current garage door however is a full 18' door and has a Double 2x12 header which is on the gable end currently.

My redesign changes this wall to one of the bearing eve walls and is carrying the second floor with attic room above in addition to a 10' shed dormer with the piggyback girder for one side of the dormer landing in the middle of this existing header.

So my question is IF THIS CURRENT DOUBLE 2x12 HEADER IS SUFFICIENT to carry this new load or if I should triple up that 2x12, or???????

Similar question, but different on the other half of the garage that is the new 24 wide X 32 long addition as it relates to the garage door headers that are needed. Here though there will be two new 9' wide garage doors with a 2' wall in between them. What size headers should I use here? Same thing going on here too......bearing wall with second floor attic trusses with 10' dormer above.

I've attached a scan of the truss and building layout if that will help.

Thanks folks!!! I'd rather ask upfront.

Jeff

 

[racer-john]

No scan.

 

[pattenp]

I have a 18' garage door in a load bearing wall with a story above and the header was specified by an engineer as two 1-3/4" X 16" LVL's. I think it's safe to say your two 2X12's aren't going to be enough.

 

[csp]

This is where you spend a little money and get an engineer involved.

You included zero information about the loads or load requirements in your area so nobody can accurately tell you what the header should be. Given the fact that you're going to 2x6s why as a minimum wouldn't you consider three bearing members for your header? LVLs would probably more appropriate.

 

[Radix2]

The company that provides your trusses should be able and willing to answer questions on headers under their trusses. When you post the drawings, it should be easy to give a ballpark here on the the requirements. Without seeing any of it I would guess that there is almost zero chance that a doubled 2x12 could work.

 

[CNGsaves]

+1 for . . . . . . HELL NO . . . . your header of doubled-up 2x12"s over 18 ft span will NOT support an added story to the building !!

Need that info on loads so GJ guru's can try to help you out. Worst case scenario you'll need pro advice from Structural Engineer/Architect.

 

[couch67]

In canada that 18' with load above will minimum be LVLs or steel depending on load requirements. +1 on everyones advice to get a recommendation, starting with your truss supplier who can likely provide the beams as well.

 

[Jawgarage]

Well, I think I am out of ideas and this is not one I want to guess at in anyway. I know lots about drawing plans, reading plans, and doing framing, electrical, etc. But I am NOT an engineer. I am expanding our 2 car detached garage and adding a second floor with an engineered Truss system. I did not use an architecht. Here is where I am stuck and nervous....

The current garage is framed with 2x4's and we plan on sistering 2x6's to that for added strength. The current garage door however is a full 18' door and has a Double 2x12 header which is on the gable end currently.

My redesign changes this wall to one of the bearing eve walls and is carrying the second floor with attic room above in addition to a 10' shed dormer with the piggyback girder for one side of the dormer landing in the middle of this existing header.

So my question is IF THIS CURRENT DOUBLE 2x12 HEADER IS SUFFICIENT to carry this new load or if I should triple up that 2x12, or???????

Similar question, but different on the other half of the garage that is the new 24 wide X 32 long addition as it relates to the garage door headers that are needed. Here though there will be two new 9' wide garage doors with a 2' wall in between them. What size headers should I use here? Same thing going on here too......bearing wall with second floor attic trusses with 10' dormer above.

I've attached a scan of the truss and building layout if that will help.

Thanks folks!!! I'd rather ask upfront.

Jeff

Here is the missing layout...........I wont skimp here if I shouldn't......Just don't want to spend it if I don't need to.......with the above roof removed for the alterations, changing out these 2x12's or beefing them up will not be hard to do.

 

[LB-1911]

As previously mentioned - No on the 2x12's.

How about the foundation - Slab on grade or footing & stem wall?

Are you sure the existing foundation of the garage is sufficient to support a second story?

 

[Jawgarage]

As previously mentioned - No on the 2x12's.

How about the foundation - Slab on grade or footing & stem wall?

Are you sure the existing foundation of the garage is sufficient to support a second story?

Existing garage is 4" slab with block foundation. Did not dig down to see what is below the first course of block but we know the former owners and builders and everything was done well past code back in the mid '80's. I will dig down the couple of feet though to double check what is there to be sure.

 

[Radix2]

Post the truss drawing with the loads on it too. Again, the guys selling you the trusses and headers will size them for you at no extra charge (around here at least...). Give that they already have the loads coming down it is simple to do.

What is the sidewall height and door height for that 18 footer- you may need some complex solution if the truss cannot fit over the header due to space.

 

[Jawgarage]

Post the truss drawing with the loads on it too. Again, the guys selling you the trusses and headers will size them for you at no extra charge (around here at least...). Give that they already have the loads coming down it is simple to do.

What is the sidewall height and door height for that 18 footer- you may need some complex solution if the truss cannot fit over the header due to space.

fortunately (I think) the 18' door is only 7' tall and the side walls (slab to top plate) are 9' so there is no issue there. New addition is being built to match that same wall height.

 

[jdlong]

(2) 2x12's is pushing it over an 18 ft span if you're adding a second floor. The deflection could easily be enough to crack drywall. You need to come up with the square footage of the 2nd floor and roof that bears on that header. Unless you plan to store heavy equipment, figure 40psf live and dead load combined for the floor. The roof could be anywhere between 20 to 50 psf depending on snow load. There are published snow load charts for different regions of the country. LVL beam MFG's publish charts for sizing beams to these loads. They even give diagrams showing how take your plans and figure the actual square footage that bears on the beam. Unless you're dealing with heavy equipment and point loads, it doesn't take an engineering degree to do the math. Builders do it all the time. It's quite simple really. You just have to sort it all out.

 

[matt_i]

As stated above, around here, a "major" old-school lumberyard will help you size the beams that you need, it will probably be slightly conservative which means another "height upsize" on the LVL.

Personally I wouldn't do any dimensional lumber, the LVL is going to be better, its straighter, stronger, and maximizes the structure that can be fit into a 3-1/2" wall with its 1-3/4" wide standard dimension. In their catalog they also talk about "bearing length" which has to do with the contact area with the framing below...in other words the number of jack studs. So study that detail carefully, it could mean adding an extra jack stud, which could mean relocating the king studs outboard (iow the door opening isn't a good idea to make smaller).

You mention adding 2x6 studs to a 2x4 wall...I would just stick with original, millions upon millions of structures have been built with 2x4s. Personally, if you are worried about "strength of the structure" I'd pay attention to reinforcing the building corners with structural screws, and the nailing pattern on the plywood or osb. If in doubt you can add Simpson's flat strapping as "X" or "V" bracing to improve the racking resistance of the walls. In other words, worrying about pure vertical compression loads (other than at the bearing area of the header as mentioned) are likely going to be fine with 2x4s. If over 10' tall then I would install mid-height center-blocking if its not already there, and also nail that from the plywood/osb in.

 

[youwish2bme]

My 28 x 36 has a 18' door that has a double 24" LVL spanning it. The 28' span is 16" TJI to clear it.

There is no way I would think a 2x12 would span any of that....

HITCH

 

[kbs2244]

You are in NJ, so I expect this project will be inspected.
Ask the local inspector what he wants to see.
It should be free and you have the assurance it will pass.

 

[Jawgarage]

My 28 x 36 has a 18' door that has a double 24" LVL spanning it. The 28' span is 16" TJI to clear it.

There is no way I would think a 2x12 would span any of that....

HITCH

Thanks. This will need inspections. Permit was already issued off of my plans which are very very good with these garage door headers my only concern. LVL or Parallam sounds the way to go. Builder friend suggests a 3 1/2 x 11 7/8 parallam beam for the 18' span. I will be asking the Truss engineer today to spec this header and the headers for the two 9' doors.

I will report back.