Mud jacking or Poly jacking choice

[jarhead]

I have just moved to a different home and the shop was added onto in 2003. The original structure is a 20x28 floating slab with stem walls for the structure to set on.

They added a 4x28 section in the back and it is monolithic. It has sank about 1 and 1/2 inches in a back corner which has left a large gap nearly the whole 28' length.

I had a well known company give me an estimate of 7K for poly jacking. I have a mud jacking company coming out in a few days to give an estimate.

7K seems a bit excessive, and their recommended repair was piers at 27K

Which method is better?

 

[jarhead]

Pics

 

[andyvh1959]

Wow, that is high just to lift the slab. Since it would not be holding any structure underneath as would a slab to support a vehicle I'd say either is workable. Though, I like the idea of a mud jacked lift that eventually hardens/sets to an almost concrete like hardness.

I wonder though, how'd they keep the poly or mud slurry from getting under the current slab. As I read it you need only the 4x28 section lifted up to the original structure level right?

 

[jarhead]

yes just the 4X28 section has sunk.
Really curious about longevity of mud jacking. I have been reading that mud jacking will eventually settle again.

 

[duneslider]

Jacking (mud or poly) is only as good at the base. It will lift it now but if the base is poor (which sounds like it is) it will sink again and you will have to jack it again. You might have to do this several times over the years.

Doing it right would probably be the piers, the point with those is to get down below the poor base you have and give it a solid footing so it doesn't keep moving.

 

[Jrad235]

They did a monolithic pour addition that's only 4 ft wide? That's terrible. So the outer wall is sitting on a narrow slab that's very long with a thickened edge(Heavier) along that side and no proper footer. That's why it is settling, too much ground pressure.
Neither Poly or mudjacking is a good fit for this long term. You need a row of piers along the edge to support the wall, and then if you want to fill the void under the slab I would go with mudjacking as it is a more cost-effective option, especially as the piers will be carrying the weight.
If you only do mudjacking or polyjacking, the slab will "walk" towards the wall of the building and make the gap wider. Piering is usually somewhere around $2-3k/Pier, and usually they are placed every 4-8ft depending on load.
Ideally the two sections would have been pinned together with rebar to keep it from separating.

 

[Fav Onefour]

Another factor is that mud jacking will not move the slab sideways. The slab has already moved quite a distance. Do you think it's done sliding? It looks like the exterior was redone awhile back. The siding hasn't split apart much after that point.

The whole deal kinda stinks. I can't imagine why they went through the effort to do a hack addition to add just four feet. The reason doesn't really matter now, but it sure is confusing.

Did they just tack on the structure to the side of existing building? If that was hacked up like the pad, maybe you can take it off and start over. In the end you could tear out the pad, do it right, and size the building to your desire. You'd spend a little more but not a huge amount to get it right.
Is your property maxed out on finished building sq ft?

 

[billconner]

You day dunk in back corner. Do you need to lift entire long edge of addition or just near that corner?

 

[jarhead]

Thanks all, thinking about tear down the 4X28 section and starting over

 

[jarhead]

You day dunk in back corner. Do you need to lift entire long edge of addition or just near that corner?

Bill,
The corner would be adequate since that is where most of the drop is. Unfortunately it has dropped a little along its entire length.

 

[jarhead]

After living here for 2 1/2 months and more thought i am really considering taking out the offending 4' x 28' monolithic slab.

I am considering putting in a 4' wall with a footer out beyond the monolithic slab another 2-4'. I would then build a new wall on that and extend the roof line. I would tear out the old monolithic pad and then tie in a new floating slab to the original floating slab. I left out allot of the details but i am curious what you all would advise?

The 4' X 28' monolithic slab is opposite of the overhead doors. Inline with the red.