max header span length

Hi, If I am adding a large bay window with a rough opening of 8ft in a load bearing first floor of a two story home can I use 2x12s for a header? I would using douglas fir. Any thoughts are appreciated. Thanks
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Assuming it's a 2x4 stud wall, you'll have to put a piece of 1/2" plywood between the 2x12's to make up the right thickness. You may also want to use double king-studs on the ends. If you frame it in right and the load you mentioned isn't out of the ordinary, you should be OK.
--
hawgeye



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snipped-for-privacy@optonline.net wrote:

Visit the Canadian Wood Council's web site and online design tool, SpanCalc. http://www.canadianwoodcouncil.ca/design/tools/calcs/SpanCalc_2002 / Make sure you understand your local code load requirements and orientation of framing members, then start clicking away.
R
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wrote:

How long has that been there?
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MichaelB
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Michael Bulatovich wrote:

Long time. They have some useful tools; a worthwhile site to poke around.
R
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wrote in message

I thought I knew the site. They bombard me with snailmail all year long.
For a while I thought about buying their structural design program to save engineering fees, but then I realized if it weren't for engineers, I wouldn't see anyone except clients, contractors, immediate family and hockey parents ; )
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MichaelB
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On 27 Jan 2007 06:44:18 -0800, snipped-for-privacy@optonline.net wrote:

I would use Pine, and make them 2x10. Is it an upstairs window?
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This is a two story house. The bay window will be on the first floor and will need to support the second floor and the attic. I measured the width of the house in the basement and it is 24' I have already framed this window in after initially looking in a few books that say 2x12s in this configuration should go to 8'. I am now unsettled as I've seen conflicting recommendations and want to be safe. Any help is appreciated. Also, can I call my town hall and ask for building requirements?
On Jan 27, 2:27 pm, snipped-for-privacy@hotmail.com (Lamey) wrote:

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if your getting a permit, I would think/hope the town permit office will require an engineers seal not just a page from a book
good luck kickstart
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After looking at max span lengths in the above link it looks like I can only really go 7' 8" in my situation. Since I need the full 8' 1" I'll need to look at a another solution like steel or lvl, microlam, etc... Which is the cheapest solution with the same 2x12 sizing? I am also going to try and get a structural engineer to help with this. Thanks all for your help.

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If you are certain that (2) 2x12s will handle a 7'8" span in your situation, then a single 4x12 should handle an 8' span. The 4x12 is 3.5" wide, rather than 3" wide, so it has 7/6 the resistance to bending moment and deflection. 8'/7'8" = 24/23, and bending moment scales as the square of span while deflection scales as the cube of span. Since (24/23)^2 < (24/23)^3 < 7/6, the increased resistance of the 4x12 exceeds the increased load effects of increasing the span from 7'8" to 8'.
Yours, Wayne
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You're scaring me, Wayne. :)
For a second I thought Nick's influence had possessed you.
But good on those calcs!
cheers Bob
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snipped-for-privacy@optonline.net wrote:

Just go to your local lumberyard an tell them your sitation and you are looking for a couple 8'LVL's. You can look on a site like TrusJoist (http://www.ilevel.com/literature/2020.pdf )for their span tables. Often times the lumberyard will call their distrubutor (or may do it on site) for a spec. on what your situation will require.
For reference, the span table above shows for a 24' wide building, snow area (115%), supporting a single floor above(40LL/12DL) and an attic, with a roof load of 40LL/15DL (highest) you would require a 3 1/2" x 9 1/4" Microllam/LVL. Many places stock 1 3/4" LVLs allowing you to gang them. This would mean you would need two 1 3/4" x 9 1/4" LVLs however you could simply go with a pair of 11 1/4" if you already have the opening framed for a 2 x 12.
It would be best to just let your lumberyard or their distributor call out the beam therefore eliminating any guess work.
Mark
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On Sat, 27 Jan 2007 19:27:42 GMT, snipped-for-privacy@hotmail.com (Lamey) wrote:

I would talk to an engineer or architect
--
+-Grant

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All, Thank you very much for your recommendations.

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My first thought is why you're using douglas fir other than its convenience in cutting and weight vs. yellow pine.
--
Jonny
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Hi, I had this sized for me and it came out to be a 2.0E Parallam PSL 3 1/2 x 11 1/4 which will fit in the existing framing. Two jack studs are needed on both ends. Anyone know the calcuation/code for king studs? I know it falls between 2 and 3 but do not have the code sheet. Thanks
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