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Upgrading floor system beam

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[#1] Posted: 10/24/2010 - 11:31:19 PM
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To supplement my meager Inspection Income I have been pounding nails for a carpenter friend and project has come up that needs a floor beam upgrade before we finish off a lower level living space.

The owner of the house wants a 24 foot clear space under the existing beam. The house is one story, built in the early 50's as a lake side retreat. the foundation is 24 feet wide and 36 feet long with 2X8 floor joist and T&G flooring. There is a center wall sitting on the floor that supports a 2X6 stick built roof. The beam in question runs 36 feet long and is made up of three 2X8's that are resting in steel post spaced 8 feet apart.

Head room is an issue, and as is always the case, so is cash. My friend has access to two 8"X1 1/2" L angles he was thinking of using by sandwiching the wood beam between the steel and bolting it together.

What we are looking to do is over-build the beam to prevent sag in the floor above. If this isn't strong enough, we may have to cut out the joists down the center and add some LVLs and hanging the joists. That would require reworking of the heating ducts and spending more money.

Comments and Suggestions appreciated.

Ezra Malernee
Canton, Ohio

Ezra Malernee
Canton, Ohio
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ezra@ezrashome.com

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Georgetown, KY
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Upgrading floor system beam
[#2] Posted: 10/25/2010 - 06:19:09 AM
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24' clear space is going to knock out two of the steel support posts leaving a beam/girder span of 24'.

That's tough with dimensional lumber.
TABLE R502.5(2)
GIRDER SPANSa AND HEADER SPANSa FOR INTERIOR BEARING WALLS

Biggest number on that chart is 11'9" & that calls for 4 2x12 on a 20 foot wide building. Adding a couple of angle irons to the 2x8 girder just don't seem near enough for a 24' span down the length of the 24' wide building.

I'd be looking for an engineer/architect type that could do the necessary calculations before I touched any of it.

By Guess & By Golly doens't seem to cut it with that long of a clear span.

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Erby Crofutt
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Upgrading floor system beam
[#3] Posted: 10/25/2010 - 06:38:35 AM
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Let me get this straight; you have a 2x8 platform with a built up 2x8 girder and a home owner that wants a clear span but he doesn't want to spend any money, right?

Good luck with that

Bolt an 18' LVL to each side of the girt and cut out one post for a 16' span. The cost to restructure it to gain another 8 feet would be close to a grand per foot.

Tom

http://clearcreekhomeinspection.com/

Life is tough enough as it is, it's tougher when you're stupid. Don't do stupid things.
Dr Joe Lstiburek
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Upgrading floor system beam
[#4] Posted: 10/25/2010 - 12:07:10 PM
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Thanks for the replies. This house is down in the sticks and most folks call people that live there Hicks. No codes, not building department, minimum government, they don't like uppity types (degreed professionals) telling them how to do it right. My carpenter friend moved into the area to raise horses. Most of his work is up here in the city or area cities that are willing to pay to have things done right.
As times are slow for him also, he has been looking at jobs down there knowing that 80% are a waste of his time. This job looked tempting (inside work, winter is coming) if he could get the beam built for a reasonable price.

If the homeowner (a woman) isn't willing to pay to have something engineered, we will walk. She will find some Hick to do it her way, most roofs down there have a sway in them, so whats wrong with a little sway in a floor.

Ezra Malernee
Canton, Ohio

Ezra Malernee
Canton, Ohio
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Upgrading floor system beam
[#5] Posted: 10/25/2010 - 1:15:18 PM
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In that case bolt on the steel, but I would set up some cribbing before pulling out the columns...just in case. I'd hate to hear about a couple of hicks getting squished in some Ohio basement.

The longest one I ever retrofitted was 19'. It started out as a triple 2x10 rough sawn hemlock. I glued and bolted on a fourth and then pulled out the column. It dropped just over an 1/8" mid span, and has stayed there for almost 20 years. There's even large format ceramic tile on the floor there, if the assembly moved the tile would crack.

Tom

http://clearcreekhomeinspection.com/

Life is tough enough as it is, it's tougher when you're stupid. Don't do stupid things.
Dr Joe Lstiburek
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Upgrading floor system beam
[#6] Posted: 10/25/2010 - 1:17:06 PM
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The problem with augmenting a wood structural member with steel is that steel and wood deflect differently under load. The steel would end up bearing the bulk of the load before the wood provided much support. An engineer on such a project as this would likely disregard the support provided by the wood and size the steel to carry the entire load. Also, steel tends to bounce more, so the calculations would need to consider that, keeping it within limits.

It's a simple calculation for the engineer. His fee shouldn't be too bad. I'd walk too if the lady refused the engineer's participation.

Marc

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Upgrading floor system beam
[#7] Posted: 10/25/2010 - 3:34:35 PM
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Hi Ezra,

About 9 years ago I rebuilt a front porch for a craftsman bungalow owner here in Seattle. The second floor extended out over the porch and there was a 25ft. clear span between the two corners that had sagged about 4-inches. The second floor overhang above the porch was originally nothing but a couple of 2 by 8's lain flat with a couple more oriented at right angles to form an L-shaped beam and then the cripple wall above that to the second floor was stood on top with some one-by sheathing skinning it. It was easy to understand how it had sagged.

I went over to the local lumber company and asked one of their designers to use his computer to tell me what size beam I'd need to span that porch and support that second floor overhang with minimal deflection. I asked him to spec something that he was certain would do the job but also something that two guys would be able to get into place. He came up with one LSL 3-1/2 by 16 by 25 or two LSL 1-3/4 by 16 by 25.

Be warned, if you use that stuff it is really, really heavy. A 1 by 12 by 16 of regular lumber weighs about 30 lbs and the same thing in LSL is about 43 lbs. Since there was only myself and one other guy, and we had to get the beam into place about 15ft. above ground level above that porch, we opted for the two beams so that we could raise them into place one at a time. Each weighed in about 240 lbs and were a #%*@^ to get into place. They did the job though. The stuff ain't cheap either. Each beam was about $10 a foot, my cost and that was in 2001.

We attached a huge ledger to the rim of that second floor, jacked it up 4-3/4 inches until it was straining the other direction, buttressed it with a series of heavy angled posts notched to fit against that ledger and wedged into pockets in the ground. Then we tore off that old header and cripple, tore out the two tapered corner "columns" of the porch, which were nothing but a pair of 2 by 4's nailed at right angle to one another, standing on end and wrapped with one-bys, placed reinforced footers and 8 by 8 pressure treated posts at the corners and spanned those with the two beams using 1-inch bolts flat washers and nuts and placing them crown up (They don't really have a crown, so we just eyeballed them and used the side that seemed to be the straightest). Then we took a strain with the jacks again, removed the buttressing and ledger and lowered the second floor 3/4-inch onto the beam. Afterward, I pulled a line from corner to corner and measured the sag. It was 3/8-inch; about half of what code allows today. After that, reframing the porch beneath it was a breeze.

When we started it was the ugliest house on the block. When we got done, it had been restored to what it looked like in a 1933 photograph. Sure, it wasn't a true period house, because the new clapboard siding was Hardiplank and we'd used engineered lumber for the bones, but when you consider that the owner was conflicted between trying to decide whether to bulldoze the house or build a new one, I think we did good.

When the painters were done it was the prettiest house on the block and with it's nice new 3-1/4 inch Douglas fir porch floors, new siding and trim and with the original craftsman style front door restored right down to the ironwork it looked like it was brand new.

I've gone over there about half a dozen times over the years to see how things are faring. It still looks pretty good. What's neat is that after that the neighbors suddenly got religion and began restoring their homes. Every time I go over there (It's in the central district), I have to marvel at the way that neighborhood has come back. Walking down that street now is like a trip in a time machine.

Go to your local supplier, Ezra, and talk to whoever specs lumber for their customers. The guy here sat down to his computer, asked me about half a dozen questions, made some assumptions based on his experience spec'ing that stuff and came up with what we needed in about 45 seconds.

ONE TEAM - ONE FIGHT!!!

Mike

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Upgrading floor system beam
[#8] Posted: 10/25/2010 - 7:07:28 PM
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Up my way, we would go drag a log off the beach, trim the top side flat with a chainsaw and pull it in there with a come-along.

It sounds like a steel I-beam might be what you need there.

Here's another thought - if you put 2 equally spaced beams in there on either side of the existing one, the span of the joists over 24 feet would be reduced to only 6 feet between the 3 beams. Then the beams could be down-sized accordingly. A couple of well-placed posts under the new beams would take the weight off the middle beam?

No, get an engineer to design a fix. Steel I-beam.





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