Beam size?

[Keel McDonald]

I'm currently trying to come up with a solution to a problem. Our living room is in our former basement. There is a support pole (metal) rith in the middle of the room. We have lived with it for several years now, but LOML wants it gone. My question is this: To replace it, I need to install a beam to support the second floor. The beam needs to span about 15 feet. I'd like to use as small of a beam as possible, but still adequate. The room is 24 feet wide, and the beam would be right in the middle, separating it into 12 foot halves. I hope that is clear enough. What size beam, and made of what, do I need? I'd really like to use wood, but will consider steel. Headroom is also an issue. A shallow beam would be much better if possible.

[Russ Filtz]

I would look at the engineered wood beams. These would be stronger than regular wood of the same size (at least the web!). Not sure if these engineered wood beams are shallower than steel for the same loading.

You'll probably not get much in the way of exact answers here. Too many variables involved. You'd need to know total load being carried (not clear if the house has 1, 2, or 3 stories!). The spans don't make sense if the room is 24 foot wide and you want to get rid of a column, you'd need a beam spanning the 24 feet. yet you state the beam only needs to span 15 feet and split the room into 12-foot halves?

I would go to a local supplier to see if they can help with sizing. Short of that, and messing with anything structural like that, you probably need local building inspectors involved, AND a structural engineer to sign off on it.

[Keel McDonald]

I was probably not as clear as I should have been. The room is 15' x 24'. The beam only needs to run 15' to divide the 24' in half. There is only one story above the living room.

[Rob Russell]

Keel,

I'm not a Civil Engineer, but I did the beam load calculations for our addition and my CE brother told me that I did them correctly ...

Saying that - for glulam/microlam wood beams - you're looking at a depth of 13-16" and 3-5" thick of beams to span the 15' and support the load without that center post. The problem is the distance you're trying to span. I wouldn't skimp on the beams, either - or you'll have a bouncy first floor. Steel would be shallower, although the logistics of tying all the floor joists into it are are bit harder.

No matter what beam material you're using, you will want to recess the beam up into the ceiling and that's going to be a project. Not something I'd try myself.

Rob

[Ken Fitzgerald]

Keel.....I had to replace a poorly constucted header on my carport with a glu-lam beam a number of years ago. I went to a full service lumber yard. I told them what I wanted to do. They picked up the phone.....called their supplier of engineered lumber....one of the company's structural engineers got on the phone with me. I gave him the slope of the roof, distance spanned......shingles....etc...all the mechanical load data. He spec'd the header for me. When I went to apply for the building permit, the head inspector asked me how I sized the beam....I told him.....They issued me the permit. You might try the same tactic!

[Keel McDonald]

Ken

We have a local truss shop, and they also supply glulams, I think. I also think they provide that same service of sizing the beam for you. I'll try that. Thanks for reminding me.


Keel.....I had to replace a poorly constucted header on my carport with a glu-lam beam a number of years ago. I went to a full service lumber yard. I told them what I wanted to do. They picked up the phone.....called their supplier of engineered lumber....one of the company's structural engineers got on the phone with me. I gave him the slope of the roof, distance spanned......shingles....etc...all the mechanical load data. He spec'd the header for me. When I went to apply for the building permit, the head inspector asked me how I sized the beam....I told him.....They issued me the permit. You might try the same tactic!

[Jim Becker]

You need the advise of a structural engineer to get the best/correct answer to your question...there are many variables including inspection of your house structure to judge where the loads are, etc.

[Bill Simmeth]

Boy, I'd proceed very carefully with this. If I understand the layout correctly, this post is most likely supporting an existing beam running the long dimension (24') which in turn is supporting floor joists running perpendicular to it. The process of sizing a beam to replace the function of the post needs to incorporate several factors including static and dynamic loads on the structure above. There are ready formulas for this, but someone needs to take care in running the numbers. I might be inclined to follow Mr Becker's advice.

[Jim O'Dell]

The next thing I would ask is, is this a walk out basement? If not, is there a way to get a piece of wood, or steel, down there to do the work? Or will temproary supports need to be built, joists cut to clear a path, and a hole cut in the side of the house to slide the beam in? I could see this as an expensive project in a hurry. I agree with Jim B. too, use a structural engineer for this. It's not something to play with and be wrong. Jim.

[Cliff Rohrabacher]

I really like steel for low head room applications.

You can also laminate steel plates inside wood beams.

[Keel McDonald]

Yes, this is a walk out basement. It would be no probem getting a beam in there.


The next thing I would ask is, is this a walk out basement? If not, is there a way to get a piece of wood, or steel, down there to do the work? Or will temproary supports need to be built, joists cut to clear a path, and a hole cut in the side of the house to slide the beam in? I could see this as an expensive project in a hurry. I agree with Jim B. too, use a structural engineer for this. It's not something to play with and be wrong. Jim.

[Keel McDonald]

Actually, the beam would support an existing beam running the other way, that is to say the 15' dimension, which currently support floor joists (12') running perpendicular to it.


Boy, I'd proceed very carefully with this. If I understand the layout correctly, this post is most likely supporting an existing beam running the long dimension (24') which in turn is supporting floor joists running perpendicular to it. The process of sizing a beam to replace the function of the post needs to incorporate several factors including static and dynamic loads on the structure above. There are ready formulas for this, but someone needs to take care in running the numbers. I might be inclined to follow Mr Becker's advice.

[Greg Cuetara]

Keel,
I am a licenced structural engineer. I would suggest that if you are really serious about removing the lally column in your basement you pick up the phone book and hire a licenced structural engineer in your area. It should only be a half days worth of work to go check out your house, the framing, and then design a beam fitting your requirements and your budget. The engineers time will probably be the cheapest part of this whole project. There are too many variables to just plug into a formula and out pops a beam size. There are also many different materials available and all will probably have to be investigated to meet your requirements. I would assume right up front that a steel beam would be your best bet but there are other issues with a steel beam. How to tie it into the existing framing etc..

The other issue is that you should really hire someone to come in and do the work for you. Unless you are a licenced contractor you probably don't have the required equipment to shore up the existing floor, take out the column and then put the new beam in place.

I would be careful of having vendors size up beams for you. The wood vendors are decent at sizing up beams for very typical situations but if it is anything but typical they falter and don't know what they are doing. Also building inspectors won't have a clue what to do or how to solve the problem. They will try to let you think they know what they are doing and they will try to follow tables or simple formulas but for your own safety hire a professional. You should be able to find a retired guy in your area who can come out for a few hours size up the situation and give you a good solution. Too bad I wasn't closer or I could stop by to help out.

Good luck with your endeavor.
Greg

[Charlie Velasquez]

I second ( or third or fourth) the suggestion to get an engineer to spec the beam for you.

I did the same thing in my basement to fit a pool table in it. I had to remove one lally column.

The engineer speced everything for me including the installation method. Made it a piece of cake to do. One thing I did not think of that he did was to check the original blueprints to verify the size of the footers under the other columns and supports to ensure they were of sufficient size to handle the added weight.

Finally, I really didn't have a choice... the insurance company required that a structural engineer sign off on it.