Strength of a header
Can someone tell me the strength of a header? This header is made of two 2x12s of yellow pine, with 3/4 inch of osb sandwiched in between. It is well nailed up with 16d nails.
This header spans five foot six inches.
How much weight would this header take before it breaks?
I have been googling it up, I am getting "40 pounds live load, snow load may increase that, first floor header must be stronger than second floor header, 10 pounds dead load, piRsquared, e=mcsquared, etc etc."
I can't figure all that stuff out. Do we have a carpenter or engineer who is good with the math who can tell me what it would take to break this header?
This header spans five foot six inches.
How much weight would this header take before it breaks?
I have been googling it up, I am getting "40 pounds live load, snow load may increase that, first floor header must be stronger than second floor header, 10 pounds dead load, piRsquared, e=mcsquared, etc etc."
I can't figure all that stuff out. Do we have a carpenter or engineer who is good with the math who can tell me what it would take to break this header?
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Where is this header located? In an interior wall, exterior wall, is it supporting only the roof load above or does it also support a second floor, third floor? Also where is the home located, which state as codes vary with location. Also what grade yellow pine is the header costructed of? Assumming 2 and better construction grade the header will support around 1200 pounds safley. 0 -
It is high quality number 2 grade yellow pine, very few knots. 0 -
Allen,
It's hard to back calculate a header strength, and it's really subjective to a flaw on the lumber used to build it. One grain weakness grossly affects to overall strength, therefore, the 2000 International Building Code and it's standards uses overkill in the calculations it uses.
Calculating header size is complicated. You have to take into account: (1) the length of the window or door opening; (2) the combined weight of the floors, walls and roofs above; (3) the building width; (4) the snow load in the area; (5) whether it's a bearing wall (where joists, trusses and rafters rest) or a non-bearing wall (to which joists, trusses and rafters run parallel); (6) whether it's an exterior or interior bearing wall; and (7) what species of wood you're working with.
The 2000 International Building Code book contains two full pages of mind-numbing charts for calculating proper header sizes in different situations. Fig. B shows the maximum allowable spans for different size headers in just one situation. As you'd expect, the deeper the header, the longer the distance it can span. But trust me, you don't want to wade into all the technicalities. There's no simple formula. My advice is this:
1. Have an engineer or architect calculate the required header size for your window and door openings.
2. Ask your local building code official to help you calculate header size. It's usually not in their job description, but the nice ones will help you out.
3. When in doubt, build a double 2x12 header sandwich like we explain next. In all but the most bizarre situations, they'll easily carry the weight for 4-ft. wide window and door openings and, in most situations, be code compliant for openings up to 6 ft. wide-a common patio door width.
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
Hope this helps.0 -
I'll place bets it will hold a full size pickup truck. Your span is VERY short,..and when you sit 2x12's (attached to one another) up on their ends (hopefully with the crown facing upwards) you have one heck of a peice of reinforcement. Especially assuming it is setting on either concrete or steel pillars. If it is resting on 2 non-load bearing partitions,..then the top plate of those walls is the weak point,..not the beam itself. 0 -
This is a short span and should be very strong.
Here is an online calculator to figure beam sizes.
http://www.lamwood.co.uk/services.htm0 -
I'd get out my Architectual Reference Literature right now, but I gave them away to Lazerus? Hey where'd he run off too? 0 -
I cannot calculate the load it will carry for you, but it is plenty strong for the opening it is in. If you have any doubt, you can always use a micro/paralam...but it is not necessary in this situation. 0 -
We don't use Pine around here, only Douglas Fir (Pine isn't graded construction grade here). Unless you have something very heavy resting on it or it is a first floor header with 2 more floors above it, the header will carry the load. Your width is 3.75" and commonly we would make garage door headers (span of 16') out of 2x12s with a piece of 1/2" ply in the center. This would be done when the lumberyard didn't have any good 4x12 beams.
You will be fine.0 -
quote:Originally posted by Alpine
We don't use Pine around here, only Douglas Fir (Pine isn't graded construction grade here). Unless you have something very heavy resting on it or it is a first floor header with 2 more floors above it, the header will carry the load. Your width is 3.75" and commonly we would make garage door headers (span of 16') out of 2x12s with a piece of 1/2" ply in the center. This would be done when the lumberyard didn't have any good 4x12 beams.
You will be fine.
I hope you are talking about using them on a gable end. They are find on a gable, but a 2"X12" header, 16' long will not carry a roof load. I've replaced several that were SEVERELY bowed in this type of situation.0 -
This help? 
Don0 -
quote:Originally posted by dongizmo
This help?
Don
Hey Don...what book is that?0 -
ECC: If you have replaced a severly bowed header that was made up like I indicated then the ply THEY used was defective. I have done this on houses that are currently over forty years old and do not have any bowed headers. And this is before trusses. 0 -
Eric,
It was a sample we got in[:D]
I wish we had picked them up, they are quite helpful[:0][:D]
The ISBN is 0-9652171-6-7
Don0 -
If the book says 5980# safely supported How much weight would break it ? 0 -
quote:Originally posted by Alpine
We don't use Pine around here, only Douglas Fir (Pine isn't graded construction grade here). Unless you have something very heavy resting on it or it is a first floor header with 2 more floors above it, the header will carry the load. Your width is 3.75" and commonly we would make garage door headers (span of 16') out of 2x12s with a piece of 1/2" ply in the center. This would be done when the lumberyard didn't have any good 4x12 beams.
You will be fine.
I have done this on both gable and reverse gables, with a MI snow load with no problems, the key is the plywood lamanite[;)]
Don0 -
Thank you dongizmo. The book says it will safely hold 5980 pounds. It looks like the chart does not include 3/4 inch of osb. That would crack the 6 ton mark for sure.
I would be interested to know what would break it.
This header is alredy installed. It is on the ceiling of the first floor, there will be two floors above it. It is an interior wall but it is load bearing. It sets on 4x4 southern yellow pine posts [pressure treated]. These jack posts each have two two by fours nailed onto them. One two by four runs up past the 4x4, and up to the top of the header for stability of the header, the second two by four is nailed onto it. These two two by fours are some kind of white pine.
I knew that on such a short span that this header would be extremely strong, especially since it is made with Southern Yellow Pine. This is the strongest softwood that I know of, in a beam configuration it is similar in strength to oak.
I would like to pile the weights up and see what it would take to break it.0
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