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heybales 08-25-2011 12:34 AM

Repair/replace sill plate and joist ends
Well, done some research on this project (much on this site too, great advice) that must be done, hoping for corrections or thoughts to my plan, plus need a couple suggestions.

60 yr house, where I discovered that through the years, there must have been many problems with keeping windows open during rain storms, and bath tub flooding/splashing/water proofing was bad, and kitchen spills/leaks/flooding.

End result is in several stretches in the crawl space, the ends of the floor joists are rotted out up to a couple inches, and/or the sill plate is rotted and crushed/collapsed where the joist rests on it. So the floor sinks across those 2-4 joist areas. The rim joist is not as bad, but I'm sure rusty nails from rim to floor joists have been useless, never mind no wood to bite in to anymore. Sill plate sitting on the outside of a concrete block foundation, with a termite shield that has rusted out in few spots, and termites got in at some point in past.

My plan is:
1. Cut out the sill plate wood back to the rim joist, except what is under a joist.
2. Sister joist equal sized wood up to rim joist, and 3 ft past the problem area. Not bolted in yet.
3. Lift those joists and sisters in that span as one, with couple 12 ton jacks and couple lally columns, following rule of max 1/8" day.
4. Once enough room, stick new pressure treated sill plate and termite shield under joists and sisters, butted up against sill plate still under the rim joist. The block wall has the space for both.
5. Bolt the sister joist in at the far end, and as close as good wood provides to the damaged area, with 3/8" x 3" lag bolts and big washers.
6. Lower that stretch and move on to next.

So questions:
Is it that bad I won't be gluing the sister joists?
Because I figure until I lift the span of joists, it wouldn't be in correct place anyway, and the gluing would just be ripped apart.

Does a solid 3 ft of good to good wood sistering sound like enough?
Purpose is not for floor flex or such, just to provide good ends for support on sill plate. Some in the bathroom may end up longer because the top of existing joists rotted out too. Ya, they had upwards of 8 kids in a 1 bathroom home for first 20 years. Ugh.

The lifting aspect, I got the top figured out. 4x4 cross supports and 1/4" steel plates against jack/columns, ect.
But the bottom part, with crawl space earth not exactly compressed as the base, I'm iffy about.

I was thinking those concrete pyramids used for decking as a base. Not sure if 4 of those (2 jacks and 2 lally columns) could really share the load of 4-6 joists and 1 story house section?
I'm sure I'd spend some time sinking them into the ground until they "bit", but is there a better idea?

And how close to the wall does this lifting need to be?
I figured within the 3 foot of the sister joist, hence my thought of putting it in place before lifting. Because trying to position it in while the lift mechanism is in place sounds like a bad idea too.

Any other suggestions, or gotchas, or you forgot this major item, or you gotta be kidding me thoughts?

Thanks much.
At least it's not literal crawl space, just hunkered over space.

Juyaya 02-16-2013 12:33 AM

Hi heybales,

This sounds like the exact same problem I have at our house. Do you mind uploading a couple pictures so we can see?


oh'mike 02-16-2013 05:36 AM

Pictures will help----3 feet is not long enough----6 to 8 feet minimum---best is full support but that is not always possible----

Jacking the floor joists one at a time causes much more damage, to the structure above, than jacking several--or the entire wall if possible----

Avoid using any masonry blocks ad cribbing --they can crush/crack/shatter with the pressure of the jack----wood cribbing is best----

It's to early for a long description----more help from others will come----

Post a few pictures if you can---look for a thread by 'alan'---he is going through this process as we speak----

joecaption 02-16-2013 06:26 AM

Use at least doubled up 2X6's, not a 4 X 4 horizontal beam to do the lifting.
Sistering full lenght joist will bring the floor back to original strength, short little patches like your suggesting will do nothing.

Gary in WA 02-16-2013 09:35 PM


Originally Posted by Juyaya (Post 1118076)
Hi heybales,

This sounds like the exact same problem I have at our house. Do you mind uploading a couple pictures so we can see?


He hasn't been back for almost a year and a half... post some pictures for us of your project!


joecaption 02-16-2013 10:33 PM

That's strange Gary because the exact same post came up on three other DIY web sites at the same time.

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