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16' Garage Door Headers

Discussion in 'Residential Structural Codes' started by vegas paul, Dec 24, 2009.

  1. vegas paul

    vegas paul Silver Member

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    Double garage doors, nominal 16' wide... I often see them on plans for detached garages. Given that the IRC is essentially intended to allow prescriptive design/building without engineering, how do you address the header span for a 16' garage door? Do you allow an engineered (LVL) or similar component, based on the spec. sheet for that beam? Or do you strictly enforce the IRC span tables (which don't address this)? I hate to require engineering on a 400-500 s.f. detatched garage.

    Just wondering how you look at these in your neck of the woods...
     
  2. Min&Max

    Min&Max Silver Member

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    Re: 16' Garage Door Headers

    The vast majority are using engineered wood products for these. Do not require an engineer to sign off. Manufacturer provides span charts and installation instructions in manual. If anal retentive, their is more info for the asking.
     
  3. Uncle Bob

    Uncle Bob Sawhorse

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    Re: 16' Garage Door Headers

    Paul,

    I see no reason not to accept an engineered (LVL) (gluelam) or similar component, based on the manufacturer's spec. sheet for that beam. That's all I've seen over the past few years. It's well within my comfort zone.

    Min&Max,

    How did you find out my real name? Anal Retentive. :)

    Uncle Bob
     
  4. vegas paul

    vegas paul Silver Member

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    Re: 16' Garage Door Headers

    Oh, I agree about using the engineered headers, per the mfg. instructions... maybe I confused the issue with my original question. What about using dimensional lumber (4 x ?, multiple 2 x ?, etc.) that aren't on the span tables of the IRC? Anybody allowing this without engineering? Even if it appears over-designed, do you allow it?
     
  5. mtlogcabin

    mtlogcabin Sawhorse

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    Re: 16' Garage Door Headers

    We run the numbers thru StruCalc if it passes fine if not they have to resubmit. We DO NOT tell them what size is needed.
     
  6. Uncle Bob

    Uncle Bob Sawhorse

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    Re: 16' Garage Door Headers

    "using dimensional lumber (4 x ?, multiple 2 x ?, etc.) that aren't on the span tables of the IRC"

    Get an Engineer for about $150.00.

    Absolutely, positively, unequivically, NO!

    Uncle Bob
     
  7. cboboggs

    cboboggs Moderator

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    Re: 16' Garage Door Headers

    We take the same approach as mtlogcabin. We run construction through a program either StruCalc or Plans Analyst. If it checks out fine if not they have to resubmit.
     
  8. conarb

    conarb Sawhorse

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    Re: 16' Garage Door Headers

    It's not that simple, almost all garage door headers require portal design, and usually narrow portals integrated with the header, this always requires engineering, listen to your uncle.

    [​IMG]
     
  9. brudgers

    brudgers Platinum Member

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    Re: 16' Garage Door Headers

    In areas with significant lateral loads from sesmic or wind, yes.

    In areas without such loads, it's not such an issue.
     
  10. Alias

    Alias Sawhorse

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    Re: 16' Garage Door Headers

    Like UB and conarb, not without an engineers stamp. As brudgers pointed out, I'm in a high wind/seismic/volcanic area plus I'm in CA.

    Luckily, the local contractors know this, it's just the DIY'er who is a potential problem.

    Sue, lost on the frontier
     
  11. vegas paul

    vegas paul Silver Member

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    Re: 16' Garage Door Headers

    Well, Sue, the DIYers is exactly why I posed the original question. I'm all for helping homeowners that want to improve their homes and I try to guide them through the IRC when they want to do their own designs/plans. Since detached two-car garage/workshops are a common project around here, I see them a lot, and I see some VERY interesting design solutions - most of them noncompliant.

    I often suggest LVLs or other engineered headers along with Hardy Walls or Simpson Strong Walls for lateral/shear on the open end. However, considering the cost of these vs. dimensional and sheet goods, usually the original design doesn''t include them.

    Thanks for the opinions... I keep striving to help out the homeowners!
     
  12. mtlogcabin

    mtlogcabin Sawhorse

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    Re: 16' Garage Door Headers

    The garage and other window and door openings are prescriptive see

    FIGURE R602.10.6.2

    ALTERNATE BRACED WALL PANEL ADJACENT TO A DOOR OR WINDOW OPENING

    A minimum 3" X 11.25" net header size is required for opening from 6ft to a maximum 18 ft. That would take care of the wind and seismic shear loads. Correct?

    A larger header may still required due to additional floor/roof loads.
     
  13. vegas paul

    vegas paul Silver Member

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    Re: 16' Garage Door Headers

    mt - As long as the walls adjacent to the door are 16" or wider, I've used exactly what you cited above - however, it seems that many want to maximize their openings (16' door) with a building that is limited by lot size, resulting in 12" in. or less by the doors! I get 18' wide garges submitted often. Won't work unless a strong wall is used.

    2nd point - It is interesting that the header in figure R602.10.6.2 goes up to 18' in length, with "min. 3" X 11.25" , which means that it might have to be bigger, depending on the actual use. But the table R502.5(1) doesn't go to 18' so how does one determine how much greater than the minimum is required? (Assuming dimensional lumber is used, not LVL). I assume the 3 x 11.25 is based on the alternate braced wall panel working for lateral/shear, and is NOT based on the header supporting the load above. That's why it's minimum for as little as 6' wide and the same up to 18'.
     
  14. Uncle Bob

    Uncle Bob Sawhorse

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    Re: 16' Garage Door Headers

    MtLogCabin,

    "A minimum 3" X 11.25" net header size is required for opening from 6ft to a maximum 18 ft. That would take care of the wind and seismic shear loads. Correct?"

    Does not state that header (6' to 18') can be "dimensional lumber"; only that the minimum net header size shall be 3" X ll.25".

    Maximum length for a "dimensional lumber" header for roof and ceiling only; would require 4-2X12s and be limited to a 14' 1" span (TABLE R502.5(1); which would require a 6" wide wall; provided the building width was not more than 20'.

    Now if they put double doors in; they could use double 2"x10"s (maximum span 8' 5"); with support in the center of the 16' foot opening; and your going to need every inch of that 20' building width. Requires braced walls to be minimum 16" wide each X 3 = 48" should allow two 8' openings (barely).

    I think, :)

    Uncle Bob
     
  15. mtlogcabin

    mtlogcabin Sawhorse

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    Re: 16' Garage Door Headers

    UB I agree and Under StruCalc what you stated is good by 85% with a .198 deflection 46lbs snow 15 lb dead loads. That's why we use StruCalc to double check submitted design loads that are not prepared by an engineer.
     
  16. Uncle Bob

    Uncle Bob Sawhorse

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    Re: 16' Garage Door Headers

    MtLogCabin,

    Thanks, I don't know that stuff; so I have to either go by the codes or Engineered. Heck, at 65, I don't want to know that stuff. :)

    It's good to know that some of ya'll learn stuff beyond the requirements of just knowing the codes.

    Uncle Bob
     
  17. fatboy

    fatboy Administrator

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    Re: 16' Garage Door Headers

    We allow and check submitted engineered products, do not do design though. Seismic and winds are not an issue here.
     
  18. brudgers

    brudgers Platinum Member

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    Re: 16' Garage Door Headers

    From my time behind the counter, it's probably a good idea to spot check designs submitted by engineers as well.

    The Braille method of plan review is not very reliable.
     
  19. Uncle Bob

    Uncle Bob Sawhorse

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    Re: 16' Garage Door Headers

    Brudgers,

    "From my time behind the counter, it's probably a good idea to spot check designs submitted by engineers as well."

    I'm afraid that as an Inspector; I'm not qualified; nor should I be expected to be qualified to judge Engineered Designs (signed and sealed) that execeed the codes. In that case, I am required to be able to read the Engineer's plans; in order to insure that the construction is per plans.

    "The Braille method of plan review is not very reliable."

    As far as plans that are submitted that are within the "Design Criteria" of R301; I also don't consider using the code requirements, to review plans as "the blind method"; and I believe my answer to the original question reflects that.

    Would be so kind as to show me what part of my answer that was wrong; or where I used the "Braile method of plan review"?

    "A minimum 3" X 11.25" net header size is required for opening from 6ft to a maximum 18 ft. That would take care of the wind and seismic shear loads. Correct?"

    Does not state that header (6' to 18') can be "dimensional lumber"; only that the minimum net header size shall be 3" X ll.25".

    Maximum length for a "dimensional lumber" header for roof and ceiling only; would require 4-2X12s and be limited to a 14' 1" span (TABLE R502.5(1); which would require a 6" wide wall; provided the building width was not more than 20'.

    Now if they put double doors in; they could use double 2"x10"s (maximum span 8' 5"); with support in the center of the 16' foot opening; and your going to need every inch of that 20' building width. Requires braced walls to be minimum 16" wide each X 3 = 48" should allow two 8' openings (barely)."

    Thanks,

    Uncle Bob
     
  20. JBI

    JBI Sawhorse

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    Re: 16' Garage Door Headers

    U B - I don't think brudgers was suggesting you were wrong. I think he was just reinfircing that plans should always be checked, regardless of who prepared them. I agree with that 100%, some of the worst plans I've seen have come from engineers... WITH a seal/signature on them.

    Simply looking for that seal/sig (or feeling for the raised seal... the 'braille' method) doesn't cut it.

    That's twice in a week I've agreed with brudgers... :eek:

    :)

    :D

    :cool:

    :lol:
     

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