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How to increase slab height 1" for sill plate

3161 Views 9 Replies 3 Participants Last post by  ront02769
New to forum.
I have a possibly unusual problem with an addition to my house.
I had concrete slab poured for a back porch and addition to interior of house.
I couldn't figure out how to add images. I don't have enough posts in forum to provide a link to flickr, so you will have to ad the www part to the link.

(www dot)

I will be removing a 10' section of wall, and replace it with a 20' wall.
The new pour is level with the main part of the floor in my house. But for some reason the existing interior floor has a down-slope to where the existing wall is (that I will be removing/replacing).
So the existing wall is sitting on a slab that is 1" lower than the new pour.
So when I remove this wall I will have to fill this 1" space before I install the new 20' wall.
I would "like" to pour a section of concrete that is 1" thick x 10' long, and about 5" wide, to raise that section of existing slab to the same height as the surrounding slab, so that I have a continuous surface to lay my sill plate for the new wall.
I do not want to leave the old wall in place and add to it because I need to re-design the wall to put in a patio door where the window now is. Also the new wall needs to come out about an inch to line up with some PVC pipes embedded in the new pour Not shown, but is where the cinder blocks are laying).
Question is, can I successfully add this relatively thin section of concrete, and what specifically should I use (think something from Lowes or Home Depot here).
The rest of the interior floor will also have to be addressed, as it slopes down to that 1" low point in about a 10' run. The finished floor will be some sort of ceramic tile.
Thanks for input!
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Around here the bottom plate is double, first layer pt, second is the bottom plate of the wall going up. So just put on your PT first plate, stick half inch plywood on top of the low one, and have at a nice level base for the bottom
Ate of your wall. Ron
I would personally get the area that the wall is at raised. Even with pressure treated, after a while it drys out and becomes food for Carpenter Ants, rot, etc..
I tried to embed, but couldn't. Forget the remodel. Lets talk about that MG.
I would personally get the area that the wall is at raised. Even with pressure treated, after a while it drys out and becomes food for Carpenter Ants, rot, etc..
Not sure what area of the country you live in....but in the northeast there is sill seal.....which is insulating layer.....and then plastic...below the PT. leaving that aside,
if PT was susceptible to all of the perils that you listed houses would be collapsing all over the land. Ron
Ron wood is wood, regardless what they do with it. Anything with Cellulose in it, attracts critters.

I would never place a bottom plate where it will be even with soil.

I have seen PT 4x4's broken at the ground and rotten when buried after 6 years.
I'm leaning more towards raising the cement vs building up the gap with lumber. Seems it would tend to keep the lumber drier. I already screwed up by not having the outside porch slab poured lower than the inside slab part, so I'm worried about water intrusion as it is.
So I want to choose the right concrete product to form this ledge.
I thought I read somewhere (on the internet so it must be true!) that minimum concrete pour thickness should be no less than 2", but perhaps that is for a full slab, not a "patch."
I would prep the old cement by cleaning and using a bonding agent.
By the way I added more pics of my project.
I'm in north Mississippi, so we do get some driving rain at times.

(@ gregzoll, which one? LOL. The pics show my daughter's '80 (daily driver), and also a late '74 that I saved from the junk yard (rusty floor pans, needs an engine re-build, at the least). I also have a "rust-reinforced" '67 parked in a garage, been setting at least 15 years, used to be my daily driver)
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Well it was too late to edit my previous post, so here's an update.
I called Quikrete, and they recommended to use Sand Topping Mix, with Concrete Acrylic Fortifier mixed in. They said that would be good from 3/8" up to 2" thick. So I think I'm good to go here.
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A whole lot easier then going with one of the options. Just make sure that your municipality is fine with that fix. Otherwise you may end up having to have that area cut out and rebar with pins put in to raise that ledge.

I was thinking one of the composites, but for what you would need to meet the proper requirements, may cost more then this other fix.
I was unable to see the pix so didn't see where it is direct ground contact....even though there are PT boards rated for same. That said, a house on " a slab" does not mean that the top of the slab is where the dirt goes to. Just finished up a Habitat two bedroom ranch on a slab where the slab sat 18" above grade.
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