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Replacement of rotted sill plate on slab

mxpro625's picture

Im an experienced general contractor trying to help out a good customer . My question is how do I replace a rotted sill plate on concrete slab? The home is a 2 story split level home in central New Jersey. I do mostly interior remodeling though i have taken on some pretty big exterior projects ( 8 section modular home , 2 story garage , 700 sq ft wrap around porch , I have some experience replacing interior beams and porch posts which require jacking up parts of home still this seems a bit out of my reach . The home has asbestos siding down to grade and a recent walkway replacement revealed rot along the back of home where previuos concrete side walk met home at just below slab. The side walk pitched in towards home. Paving contractor pitched new walk away from home,I know this will help shed water away. There appears to be no sagging or structural problems along back of home, no sagging roof line , cracks , and all doors and windows are operating ok. Still there is significant rot there and it appears to me the home would need to be jacked up slightly to replace this plate .

(post #101683, reply #1 of 8)

This is posted in the Fest folder.

You might get more responses if it was posted in the General Discussion or Construction Techniques folder.

That said.

I have one experience with this. I replaced the sill on a two story garage (upstairs apartment) on a slab.

I lag bolted (two per stud) a 2x8 to the outside of the wall (into the studs) and then used that to bear the jacks on. I think I did about eight feet at a time. You only have to go up a little bit.

It helped that vinyl siding was going up as soon as I was done, so the holes in the walls didn't matter.

Whether any of that would apply in your situation, I don't know.

It proved to be easier than I thought it would (I was scared to death of it), but it still took a long time. I doubt I got more than 16 feet done in a day.

Rich Beckman

Another day, another tool.

(post #101683, reply #3 of 8)

Thanks for the reply , it really helped in coming up with a plan. I actually thought up somthing like your idea so it was good to get some comfirmation on that . Ive worked up a worst case scenario plan as well working from inside and out , and using multiple jacks on 2nd floor joists as well as attaching 1st fl studs to top plate with metal tie plates.I also have some help from some one with rigging experience . The customer is prepared for the worst for my next trick ............. Ahhhhhh ! aint contracting great! Thanks again pray for me .  steve

(post #101683, reply #4 of 8)

"and using multiple jacks on 2nd floor joists as well as attaching 1st fl studs to top plate with metal tie plates."

Well, as I said, my experience is limited so I may not know what I'm talking about here...

If you jack the 2nd floor joists aren't you likely to leave the wall behind?? Or does the tying of studs to the top plate mean tying the wall to the joists?

Seems to me you want to jack the wall, not the 2nd floor joists.

But again, I've only the one experience.

Rich Beckman

Another day, another tool.

(post #101683, reply #5 of 8)

No your correct it seems I would need to do both if im not successful out side . again im not looking to jack up house as much as being sure to take pressure off 8 ' of sill plate at a time. The attached garage should be easier as its only 1 story and light weight .By jacking up joists at ends im more comfortable with the amount of weight and support below jacks due to being over footings. If I dont see measureable progress jacking up from out side Im going to plan B inside and also using outside . I recently completed a $19,000 bathroom directly above this wall and Im aware of how gentle Im going to need to be . My goal with attachment plates is to secure top plate , joists and wall studs so i move everything at once. Ill cut sill plate loose at start. thanks for the heads up , Im planning on starting 2nd week in august so Ill be continuosly looking for any new info.  Steve

(post #101683, reply #2 of 8)

I'd start by having a look in the attic to see whether this wall supports rafters and ceiling joists, or runs parallel to them.  If it supports them, you can transfer the load to a falsework wall.  If you don't want to mess with the asbestos and moisture barrier, you might figure on demoing the bottom couple feet of drywall and working from the inside.  But if the outside's already open, then that's the way to go. 



-- J.S.




-- J.S.


(post #101683, reply #6 of 8)

i got into this once and had no luck going up,even a little. my studs were fine so i put jacks similar to whats been described,then took a recip saw and cut the nails off the studs.then cut ,chiseled ,pulled the old sill out and sledged the new one in. it was a tight fit but got new wood in there. larry

hand me the chainsaw, i need to trim the casing just a hair.

the older i get ,

the more people tick me off

(post #101683, reply #7 of 8)

We usually use an LVL attached to exposed studs in the area in question with 1/4" x 4" timberlock structural screws.  The screws drive in quickly with a big drill and are quite tough.  LVLs are cheap and quite strong to jack against.

Warn the clients that the screws have the potential to puncture hidden pipes or wires and reach an agreement as to who picks up the bill if something is hit.

We'd rather cut an extra 1/4" from the studs to allow the new plate to go into place easier.  Add a structural shim (no cedar) to make up the difference after the plate is in place.

Finally, don't forget that the plate is still holding the house in place so drill and epoxy new hold down bolts into the concrete and bring any other hold down requirements up to code.

Good luck

(post #101683, reply #8 of 8)

Good advice here, I would just add that even though you've got serious weight involved, don't be intimidated - like it has been said, you aren't lifting a house, just taking some pressure off short sections long enough to whap in the sill. It's like changing a flat on a car -except probably safer because a car has to be raised ten or twelve inches and can wobble. Good luck

I'll. Be. Back.