Composite I-beam question

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papakevin

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Not sure this is the correct thread for the my question, but since it involves structural integrity, might be the best place.

I have a finished ceiling in the stairway going into my basement and there is a low area at the bottom due to the composite I-beam which runs across it. This beam is supposed on both sides by load bearing walls. If I were to add 3/4 plywood to either side of the beam, using liquid nails and screws to secure to both sides, could I cut into the beam and remove the bottom 1/2 of the beam (about 6”) to increase headspace? I would only do this in the stairwell area. If this isn’t appropriate, what are some other suggested fixes? Photos of the stairway attached along with a photo of a beam from another location for reference.
 

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Steve123

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There are rules for maximum size notches that you can put in a joist. I assume you have already googled them.

On an engineered I joist like you have, the joist is engineered to specifically have the load taken mostly by the upper and lower members of the joist. So cutting one of them away is particularly problematic. I don't see how screwing and gluing to the OSB web is ever going to restore the strength,

If its only the one joist, only thing I can think of is put a steel I beam right beside the existing joist.
 

papakevin

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I like the idea of adding in a small steel support to help carry the load and reduce the risk of failure due to the compromised composite beam. I would be cutting the composite I-beam only in the stairwell - which is probably 3 feet wide or so. I’ve read adding support on either side of the webbing reduces deflection (stiffens the beam), so was assuming it would add some structural value as well.
 

bud16415

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I agree with oldog’s post above.



The material can be removed and additional support can be added sistered to the I-joist to make up the lost strength.



If it were mine and I were there to see the big picture I think I could over design a solution to solve the problem safely on my own.



It is my opinion though that you are new enough to this to need some help on the solution and the process to make it a DIY project for yourself. We see just the area of the problem and what is important is what is in the walls adjacent below the I-joist and also what loads are being carried above.

If we were to guess at a solution for you and then some problem were to arise that would be a bad situation for everyone. I feel that once you have a plan there should be no problem in you doing the work and we will be happy to review what you find out and assist in doing the work if you need help from afar.
 

68bucks

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+2 on consulting a structural engineer for all the reason that have been stated.
 

rbm328

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+3 for a structural engineer.
we removed a wall in our late 80s 2 story house and by trade, im a civil/mechanical designer, so I looked up the loads and came up with 2-2x12's sandwiched, BUT I also contracted it out after talking to a General Contractor and he came up with the same support. We did have some fly by nights say they'd put in a 4x6! we said thanks, we'll let ya know!
 

68bucks

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+3 for a structural engineer.
we removed a wall in our late 80s 2 story house and by trade, im a civil/mechanical designer, so I looked up the loads and came up with 2-2x12's sandwiched, BUT I also contracted it out after talking to a General Contractor and he came up with the same support. We did have some fly by nights say they'd put in a 4x6! we said thanks, we'll let ya know!
I'm a mechanical designer too and we removed a section of wall under a support beam to make a hallway. I figured what I would need for a header but still brought in a structural guy to confirm. Cost me $150 I think. Found the guy through some contacts.
 

papakevin

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Thanks for the advice. I’ll start looking for a structural engineer and get his thoughts before I do anything too stupid.
 

bud16415

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Thanks for the advice. I’ll start looking for a structural engineer and get his thoughts before I do anything too stupid.
I think some of us might be willing to venture a guess to what you want to do but feel there is not enough information to venture that guess.



All beams that are loaded get their strength from the extreme fibers as an example the top of the beam loaded from above is in compression and the bottom in tension and right down the middle is called the neutral axis. These manufactured beams put most of the fiber where it is needed most and then have greater height per a given weight moving the extreme fibers farther apart. The same is true if you look up in Wal-Mart the roof is built from what is called bar joists where you have angle iron top and bottom laced together with small rods. Steel I-beams of course do similar.



Wood is stronger under compression than tension so in your case cutting out the bottom cord all the way to the neutral axis is about like chopping out the whole joist in that area.



When you remove the support of one the ones beside it are forced to take on the extra load and how close they are spaced is a factor, along with what the beam was designed for and what it actually is seeing as in the floor loading above. When your house was designed some factor of safety was built into the numbers and that is an unknown as well to us. Then there is what’s behind the drywall walls framing the staircase that may also be supporting the I-joist on each side of the area you would like to remove and is the floor it is resting on up to the task of taking extra load.



They will factor all this in and then determine how much extra strength the cut area will require.



They maybe will not be able to give you a 100% structural evaluation given you wont want to pay them for a long study and testing. But be able to give you some idea just based on having done similar many times in the past. They may also give you what seems rather excessive in terms of what you would need to do than a handyman like myself as a home owner would give a try and the project could balloon to where you won’t DIY and to hire it done you will live with the head knocker rather than hire it done.



It will be up to you in selecting someone to take a look at it all and then evaluate what they tell you. I would strongly suggest do not find someone that also owns a or is connected to a company that will do the work for you. Sometimes word of mouth etc is not a bad idea if you know someone that just had some project designed. Even a retired builder etc might offer an opinion.



You may have to pull some drywall to get the big picture also.

Good luck and let us know what you learn.
 

oldognewtrick

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Just to echo Buds comment, choose an independent engineer that's giving an assessment not there to bid the job.
 

Eddie_T

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I wouldn't offer any long distance advice but if it were me and other factors considered I might go for vertical members R&L in the beam, lally columns on each side, sandwich the web with 2x6 then remove material.
 

Steve123

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Am I missing something here ?

We are talking about a joist, not a beam, right ?

Hire an engineer to specify a 4 foot long joist ?????
 

oldognewtrick

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He described it as a beam, from the stair pic it appears to be the main center beam. From my house I can't tell. Better safe than sorry.
 

Eddie_T

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If it's a joist there will be more of them above the dropped ceiling tiles of the lower level.
 

bud16415

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I'm not a structural engineer, but for such a short span, it seems like nealtw's idea in post #17 would work.
It most likely would. What we don’t really know is when a staircase cuts thru the floor both sides of it have to support the load around it on both sides. Where the staircase ends at the bottom we don’t know from the photos how all that framing is run and how the loads were carried and if there is footing below at that load points or not. with a finished basement you can’t see how the framing run and the photo that shows it open I’m not sure if that is the area or not as in some photos that seems to be finished over.



If the OP wants to do more investigation maybe removing drywall in a few places folks might offer more opinions. If I was going to do something like Neal suggests I would glue and clamp the pieces in and then use a lot of construction screws that would go thru the whole stack from both sides and likely run the 2x6 headers out past the support walls as far as I could gluing and screwing.



A lot of judgment goes into these things when you don’t work to numbers and in my case I really over-design if I don’t know.

It is not a good feeling to start into cutting something and get about half way thru and hear a loud crack. Not that it can’t happen after having someone come and give you advice but at least then you have someone to blame it on.
 

Mike/21

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I was looking on Bailey floor joists (lsf system) and they specifically mention their being an alternative to engineered wood. I'm sure you could look at the load tables and get something of similar strength and gain the space you want. While I would never argue against having someone take a look see, if the joist you are cutting is supported on both sides of the stairwell I highly doubt it's the keystone piece that will bring your house down. or tear out the stairs and make them steeper(jk)
 
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