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Header Questions

kbirk

Registered User
Joined
Apr 11, 2023
Messages
4
Location
wisconsin
Hello, I am building a detached garage. My lumber company is helping with the design. I am just getting more support (confidence) with the design. Here is a picture of my layout. I want to get the headers correct. I don't mind over doing it. I researched building span and header sizes but cant find anything that describes my build. The 10 foot garage door and 8 foot garage door will have a span of 10'3" and 8'3". The building has a span of 26' with 6/12 hip roof. The walls will be 10 feet (ish) tall depending on me getting 9' 1.5" clearance for the 9' doors. The overhang will be 18".

Can anyone help with pointing me in the right direction on header sizes? I am hoping to use 2 LVL 9.5"x1.75" (I can get my 9 foot tall door clearance without a raised curb on my slab.) Thanks








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I can't give you aid, as I'm Canadian (different sets of codes up here), but you may want to provide your location.
I'm assuming that under 'murican codes, lintels in Maine will have to be beefier (snow loads) than lintels in Arizona.
 
It's not terribly difficult but snow load in your area as well as attic if any are important factors. Once you have pound per lineal foot, lumber yard can size. My gut says 9.5" deep won't cut it for a 10' load bearing header but I could be wrong.

Based on sketch and door sizes, you have some work to achieve the required lateral bracing in the wall with overhead doors. Google garage portal framing for a start.
 
I was going to write a response based on the IRC, but then I checked and apparently WI hasn't adopted the IRC. Instead they have a "Uniform Dwelling Code" which includes Administrative Code Chapter SPS 321, "Construction Standards":


I'm not familiar with that document, so I may be overlooking some global guidance on using it. But just jumping to the section on headers, Table 321.25-B for those supporting a roof/ceiling and no floors, it says that (2) 2x10s in Zone 2 (southern half of the state, 30 psf snow load) with a 26' building width can span 7'.

[I'm not aware of any prescriptive guidance on how to handle hip roofs, so I'm just treating the building width as the same in each direction, as the common rafters in each direction will span 13' horizontally from plate to ridge. Of course with the hip, there's only one common rafter on the short side, the others are jack rafters bearing on the hip rafter. And sizing the hip rafter itself is the tricky part.]

However, the footnote to the table says "These tables are based on wood with a fiber bending stress of 1,000 psi. For other species with different fiber bending stresses, multiply the span by the square root of the ratio of the actual bending stress to 1,000 psi." Apparently in this code headers are sized for strength only with no regard to deflection.

LVLs can have fiber bending stress values of 1500 to over 3000 psi, depending on what model you by. So if that guidance applies to LVLs as well as solid-sawn lumber, to span 10' 3" with the 2x10s, you'd need an LVL with a fiber stress that is at least (123"/84")^2 = 2.144 * 1000 psi, or at least 2150 psi. And that treats the LVLs as 1.5" x 9.25", smaller than the actual 1.75" x 9.5", which deviation is conservative.

On the other hand, ignoring deflection isn't really conservative, particularly as LVLs may give you a bigger ***** in allowable bending stress than they do in modulus of elasticity, which determines deflection.

You'll need to review the rest of that document to check on minimum wall depth (2x4 vs 2x6) depending on the wall height you have (since you mentioned 10' tall garage doors), as well as the required details for lateral resistance, as previously mentioned, among other things.

Cheers, Wayne
 
Have your headers run the full length of the wall from sheathing to sheathing. with your 2 foot wall section on each side of the openings you should be able to resist the lateral loads

FIGURE R602.10.6.3
METHOD PFG—PORTAL FRAME AT GARAGE DOOR OPENINGS IN SEISMIC DESIGN CATEGORIES A, B AND C

R602.10.6.4 Method CS-PF: Continuously sheathed portal frame.
Continuously sheathed portal frame braced wall panels shall be constructed in accordance with Figure R602.10.6.4 and Table R602.10.6.4. The number of continuously sheathed portal frame panels in a single braced wall line shall not exceed four.


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O my I have a new favorite web site. Thanks Thanks Thanks! I found this pic when I built the house of how the architect drew it up. The 18 ft. opening had a double 11 7/8 LVL and the 8 door had a double 9 1/2. My detached garage will be a duplicate to my attached. The material list from the lumber yard shows my new garage headers are double lvl at 9 1/2" and 14 and 12 feet long. sheathing to sheathing :) Starting to make sense :) MyMail-17241386915223831821.JPGFraming (36).JPG
 
O my I have a new favorite web site. Thanks Thanks Thanks! I found this pic when I built the house of how the architect drew it up. The 18 ft. opening had a double 11 7/8 LVL and the 8 door had a double 9 1/2. My detached garage will be a duplicate to my attached. The material list from the lumber yard shows my new garage headers are double lvl at 9 1/2" and 14 and 12 feet long. sheathing to sheathing :) Starting to make sense :) View attachment 10477View attachment 10478
I would say that does not comply with the IRC because of lack of adequate lateral bracing. Maybe an engineer can determine otherwise, but not a builder, because the header stops short.
 
If you cannot provide a reference to a proscriptive code provisions the building department should expect you to be able to show how you determined the headers and the shear walls. Hiring an engineer to assist will resolve your questions and answer the questions from the building department.
 
If you cannot provide a reference to a proscriptive code provisions the building department should expect you to be able to show how you determined the headers and the shear walls. Hiring an engineer to assist will resolve your questions and answer the questions from the building department.
I don't disagree, but it is nearly impossible for the average homeowner to find an architect or engineer interested in a small project. I contacted every engineer in my county and adjacent counties, and the very few who actually had the courtesy to return a call or email simply were no interested. Very frustrating.
 
If you cannot provide a reference to a proscriptive code provisions the building department should expect you to be able to show how you determined the headers and the shear walls. Hiring an engineer to assist will resolve your questions and answer the questions from the building department.
I don't disagree, but it is nearly impossible for the average homeowner to find an architect or engineer interested in a small project. I contacted every engineer in my county and adjacent counties, and the very few who actually had the courtesy to return a call or email simply were no interested. Very frustrating.
Thanks guys. I am working with Menards (lumber yard) design team for the design. I am here to learn as much as possible to have trust with their design. It will be me and my family that will be under them headers n roof with 4 feet of snow on the roof. After I receive the final plans I will forward to my building inspector for agreement. Trust but verify ole Ronnie use to say
 
If you cannot provide a reference to a proscriptive code provisions the building department should expect you to be able to show how you determined the headers and the shear walls. Hiring an engineer to assist will resolve your questions and answer the questions from the building department.

Thanks guys. I am working with Menards (lumber yard) design team for the design. I am here to learn as much as possible to have trust with their design. It will be me and my family that will be under them headers n roof with 4 feet of snow on the roof. After I receive the final plans I will forward to my building inspector for agreement. Trust but verify ole Ronnie use to say
That can work but consider erring on the if in doubt build it stout or if you prefer presidential idioms walk softly but carry a BIG stick.

You probably wont have too much problem with header but you really should pay very close attention to lateral bracing and the portal frame issues.
 
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