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Engineerd Floor Joist Repair - Damaged by Exterior Water

Engineerd Floor Joist Repair - Damaged by Exterior Water

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  #1  
Old 10-21-12, 05:54 PM
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Engineerd Floor Joist Repair - Damaged by Exterior Water

I have two adjacent engineered (I-beam) floor joists that have been water damaged from exterior seepage which made it through the tyvek and down an exterior wall. The damage to the floor joists is small, maybe two inches on the end of the I-beam as it sits on a 2x 6 (or 8) sill. Replacing whole joists would not be easy, but to ignore it will not be good as I have to replace some rotted wall studs and plates above it.

All the posts just deal with stiffening. How do I repair? My guess is filling the web for about 3' with plywood, adhesive and framing nails and then adding 2x wood the same height as the i-beam for 3' would suffice.

Advice?
 
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Old 10-22-12, 04:43 AM
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Any way you can post a few pix (not close ups) of the areas in question? That way we can see what you see. http://www.doityourself.com/forum/el...your-post.html
 
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Old 10-22-12, 04:20 PM
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Old 10-23-12, 05:34 AM
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Yikes, that does look bad

I'm just a painter but the fix you described in your first post sounds good to me - I'd do it on both sides of the joist. I'm sure one or more of the carpenters will be along later to either confirm or give better advice.
 
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Old 10-23-12, 01:34 PM
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I'm not a carpenter, but will chime in anyway. If it were mine, I'd completely remove the rotted ends by sawcutting, then splice in identical replacement pieces of engineered joists, using glued-and-screwed 1/2" plywood on each side of each joist's web plate. Since the ends of joists are subject to mostly shear loads (as opposed to bending moments out near the centers), and the webs are what resist shear loadings, you probably wouldn't even need to splice the top/bottom flange plates.

You definitely need to stop the water intrusion before doing anything, or you will be doing it all again (joist, stud, sill plate, sheathing repairs) in the not-too-distant future.
 
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Old 10-24-12, 02:40 PM
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You might also consider using an epoxy wood-filling and -preserving process, so that you wind up with a structure that resists water damage. Here's one example: Wood Restoration & Maintenance

Do get rid of the water first, if you haven't already done that.
 
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Old 10-24-12, 10:41 PM
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Thx all; in the interim, I did locate Weyrhauser's (sp?) silentfloor truss specs and guides. There was a really handy guide that I can post the link to if you're interested. If so, I will do when I get the pictures posted to help close out the thread.

As bridgeman45 will know from the other post on brick/masonry, I have stopped the major water flow issue with some step flashing. This will keep it dry enough to repair, then I will get after the other 10% (counterflashing, added downspout).

In the interim, based on the tech specs, I filled the webs with 5/8" plywood, from the edge back for 3', glued and screwed in the allowable "zones" (basically, a no hole zone in the first six inches from the joist edge). I then added 3/4 ply across the entire height of the joist for the three feet, glued and nailed (4 corners on the perimiter, 4 rows of two in the interior). This provided ample strength and beef to nail the new rim joist into. Also toe-nailed the resulting beam into the sill so it all seems very stable. If shear is still a concern, could add blocking to the sill to further stabilize.

Am onto a different problem with framing which I am going to start a different thread on. Thanks for the help, and, as I said, I will post pictures to help this thread support others in the furture.
 
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Old 11-01-12, 11:51 AM
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you might just want to cut those ends off and sit a beam on the top plate and bucket those I joists into that
 
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Old 11-01-12, 12:21 PM
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I'm not a structural engineer so I may be all wrong about this, but I don't think your repair is adequate. These are two adjacent load bearing members and if I'm reading your post correctly you have replaced a piece of engineered wood, that depends on the integrity of all the pieces, with some glued up plywood. What happens when the rotted pieces of wew and flange continues to rot even after the water source is removed?

I didn't see squash blocks alongside the ends of the joists. When I built my garage I changed the plans (after the permit was issued) to I joists instead of traditional dimensional lumber. The building inspector approved the change but added the requirement for squash blocks at the ends of the joists and where they crossed a support beam. Anyone know if this is regional or is it a code requirement?
 
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Old 11-10-12, 08:22 PM
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How does a squash block differ from filling the web, both sides, with 5/8" ply and then gluing 3/4" ply on both sides of that. That's 2-3/4" of new wood, running back for 3' from the end, reinforcing the original Trus-joist. If the OP used CDX or better, it sounds like a structure that can support a lot of weight and a bit of torque too.
 
 

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