Need to figure out the weight capacity of double 2x6 header?
Question:I am doing a remodel, and the building inspector is coming Friday for my rough-in. I installed new windows, but used the existing headers. The windows are 36" wide, and the headers are doubled 2x6's. I thought they would be "grandfathered' in, so I didn't change them, but have since found out that nothing in the old building will be gradfathered. There is also a double top plate on top of the header. It is only carrying one rafter, and the building is only 20x24, so there is only about 10 ft of roof being supported. To me, 2x6's should be plenty, but I would like some strength/stress data to show the inspector in case he gives me a hard time. Can anybody help? Thanks.
Answers:
i would suggest calling a few structural engineers or construction companies and see if they can provide you an answer. hopefully they all supply the same info.
It doesn't matter what you show the inspector, if he says no, then it's no. Technically, it is strong enough, but the code is the only thing that matters.
My back porch uses a double 2x6 with 1/2" OSB in the middle. The posts are spaced six feet apart with 3/4 tongue in groove plywood and shingles. The headers haven't sagged a bit in seven years.
Headers on new construction are still done with 2x6's (the 2x6's sandwich a 1/2" piece of lumber to get you the 3.5" width of the 2x4's framing the outside of the opening). From the way it sounds, you are just fine.
http://www.rd.com/familyhandyman/content...
FIG. B
HEADER SIZE
MAXIMUM SPAN
NUMBER OF TRIMMERS
Double 2x6
4 ft., 0 in.
One
Double 2x8
5 ft., 0 in.
Two
Double 2x10
6 ft., 2 in.
Two
Double 2x12
7 ft., 1 in.
Two
Most inspectors will work with you, but your best bet is not to mention the windows, and he might not remember to notice.
I would play stupid on this one. If he (or she) brings it up, claim you didn't think about it. It held it up for such a long time, why would it be a problem now?
If he wants to give you a hard time about it, figures and diagrams you can get from the internet will not help, and often arguing the case will cause you more problems with other items that may be a real issue than it is worth. If it is going to be a problem, you will save time and money by replacing the headers with what he wants. If that is not practical, find a local engineer to draw something and stamp it.
I don't think it will be an issue anyway. Your double 2x6 is at about 29% capacity if you have trusses with no mid bearing, less if you have rafters. A single 2x6 would do it. If your inspector has much experience, you will not have a problem.
If you glue(PL400) and screw a peice of plywood(not OSB) to the face of this double 2X6 you'll have more than enough strength. OSB to me is nothing more than garbage board. It's garbage with lots of glue to hold it together. PLywood is still the best, although it is more costly.
for a 36 in window, double 2/6 would be ok. but double 2.8s would be better. but you dont need them. if inspector doesnt say anything, you are home free.
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