I-Joist Repair


Old 11-14-11, 12:40 PM
Thread Starter
Join Date: Feb 2008
Location: USA
Posts: 37
I-Joist Repair

What is the best method to repair a short ~4ft section of I-Joist whose entire bottom flange sits along a 4ft section of the foundation outer wall and then along a steel I-beam.

Here is a pic showing the water damaged sub-floor looking up from the bottom and about the 1st 16 inches of the I-Joist being affected:

The pic below shows how the I-Joist runs along the foundation wall sitting on top of a steel I-beam as opposed to having just it's end resting on the foundation.

the following pic is a view from above after having removed the hard wood flooring and drywall in this area:

Here the bottom plate has been complete rotted out and what you see is the damaged "top flange" portion of I-Joist. The brown material adjacent to the flange and the brick veneer is the sheathing that has also rotted. finally you can see the one of the corner posts studs has lost about 4 in of material.

How do I need to cut out this section of the I-joist and replace it?

Since it its full length sits on top of a steel beam which sits on top of a poriton of the fundation, how would I jack the supporting wall to replace the damaged section of I-Joist?

All of the examples I have seen are when the wall being supported is perpendicular to the floor joist. In this case the wall supported by the I-joist is parallel to it and directly on top of it.
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Old 11-15-11, 10:30 AM
BridgeMan45's Avatar
Join Date: Oct 2011
Location: USA
Posts: 3,196
Don't do anything to the rotted/corroded members until after you've corrected the seriouswater intrusion problem. If you don't stop the water from getting in, damage to replacement members will just continue to occur.

As you appear to have a somewhat complex situation, you might want to consider bringing in a qualified engineer to evaluate things and develop a repair plan. Without knowing more of the particulars of the complete structural support system in place, it's hard to give specific repair suggestions. The presence and orientation of the steel beam would normally indicate it supports a load-bearing wall above, but that does not appear to be the case based on the view from above (last picture).

In very general terms, the damaged steel and wood material all needs to be removed and replaced, after installing appropriate temporary supports to hold things up while the work is being done. The normal processes to cut out and splice in a short length of steel beam involves flame-cutting and welding, which in your case would pose considerable fire risk to adjacent wood members. In view of it appearing to be somewhat light-weight steel, it might be better to remove the existing steel end by saw-cutting and then angle-grinding to clean things up. There may still be sparks, but they will be minimal, and can be addressed by frequently wetting things down with water spray. A mechanical splice connection (bolted flange and web plates) could be used to attach the replacement piece of beam. As for the rotten engineered wood joist, a custom (fabricated to fit) replacement piece of built-up wood could be tied in, using recommendations furnished by Truss-Joist or one of the other engineered joist manufacturers.
Old 11-22-11, 04:34 PM
Join Date: Jun 2008
Location: Southeast, Pa
Posts: 358
You definitely need to bring in an engineer to let you know how to handle the repair properly and it's probably not a do it yourself situation. I doubt he will make you remove any of the steel beam. I agree that you should get the leak repaired before doing any of the structural work.

I believe the way the I-joist is sitting on the beam will make any repair easier than if it did not sit fully on the beam.

Good luck,


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