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wood beam strength

11/28/17       
RIck Member

I hope someone can shed some light on this question. I am moving a wall were the beams that run across the 2nd floor meet and run about 3 feet past each other. Im no engineer nor I have the money to hire one. What im proposing to myself is to run a 8x10 doug fir beam across to support the beams that run across. I will cut into the beams that run across (about 10 of them) and stick the 8x10 into them and attach framing brackets on each side of the beam attached to the 8x10. its a 12 foot span and theres nothing but a hall way above and a bathroom, so i cant see it taking much weight?? Also it will be sitting on 1 4x4 on each end. Im just worried about the 8x10 sagging or worse not supporting the weight... Any insight? the 4x4 will be sitting on a formed part of the foundation by the way. thanks! Any information will be greatly appreciated.!

11/29/17       #2: wood beam strength ...
Leo G Member

Call an engineer. That's the only way a building inspector will pass it.

12/1/17       #3: wood beam strength ...
Mark

While carpenters are often tasked with making "seat of the pants" span and load calls, I agree with Leo here- go to your local building inspector and ask him what to do and who to call, since you've never done this kind of framing change before.

The "beams" in the floor are called joists
The "framing brackets" are known as joist hangers
If you are using an 8" wide beam, you should support it with an 8" wide post. And installing it between the joists as you describe is installing a flush beam. Also, laminating 3 LVL's will carry more load.

Again, talk to your building department, they're there to help

12/2/17       #4: wood beam strength ...
Alan F

The UBC and other building codes have span tables in them, that will help size the beam. You need to know the live and dead loads of the floor above to size a beam. Part of that is local code and part of it is intrinsic to the whole design.

The bigger issues is generally a structural 4 x 4 would be supported by a footing underneath and if you are in high wind country the connection to the footing needs to resist upward movement.

So this is the long answer that gets us to Leo's short answer. You could also work with an experienced structural contractor.

This is not seat of the pants math.

When I was younger I held a contractors license that allowed me to build up to 6 story buildings and I built a lot of office building as well as other structures. I could figure the math from the tables if I had the plans and knew the facts, but its a call the engineer type question

What you can't afford is to have it fail and because you didn't permit or hire a professional have your insurance deny any claims.

The risk reward on not calling an engineer is the potential loss of life, home and finances.

sample span tables

12/3/17       #5: wood beam strength ...
rich c.

Yup, you need the loads on the second floor. Guessing and saying you have no money for an engineer could only spell disaster. Maybe it's only your own building that is at risk, but can afford to loose it? An 8x10 sitting on a 4x4 is also a disaster waiting to happen. You might not even have to worry about the beam when that 4x4 fails.

12/4/17       #6: wood beam strength ...
Adam

If you don't have enough money for an engineer. Find some money to pay a good carpenter who can see this with his own eyes for his opinion and recommendation. Based on your questions it is obvious this project is above your experience and skill set. You need some real help...not WoodWeb.

12/6/17       #7: wood beam strength ...
Mark

+1 with Adam
I tried to say the same thing, perhaps a little softer.


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