Leveling a slab foundation

[dwg]

I have a bedroom addition to my house (about 10'x14')  whose floor is out of level by about 2"-3".  Both the house and addition are "slab on grade."  The two methods presented to me so far are to use Helical Piers or Steel Push Piers to raise the slab at one end to make it level.  I was wondering if anyone favored one method over the other?
Thanks.
Don

[K. L. McReynolds]

Would mud jacking work? Less/more expensive?

[dwg]

I don't think "mud jacking" would work as the slap and footing are poured together'

[Cooler]

Was the addition originally a porch?  The incline might have been put in for drainage away from the home.  It might be solid, just not level.

If that is the case  you just need to level with wood stringers and a sub-floor.

[Mr_Mike]

Cooler, good question. If he fixes the slab, does he screw up the ceiling and roof?

Needs to be thought of as a system.

[Robert Adams]

Was the addition originally a porch?  The incline might have been put in for drainage away from the home.  It might be solid, just not level.

If that is the case  you just need to level with wood stringers and a sub-floor.

 That method works pretty well. Have done that to to a few garages to turn them into living space or shop space. 

       Here sinking slab foundations are very common. Older slabs will have trenches dug around the perimeter and a few internal to act as beams. Newer houses are post tension as its cheaper and faster to do than a traditional slab. 

         The preferred jacking method here varies on soil type. IE is it all clay or is it clay and rock or is it rock with a little clay. Screw piles are the most common repair here. Lots of different big names and just as many that are the same thing but without the big name to raise the cost.


         If it's fairly stable now you could just pour concrete on top and level it off. Something like gypcrete if it's available(very uncommon to find a contractor that can do it). Or the above mentioned method.  
 
           All up to you and what it's worth putting into it.

[dwg]

This slab was never a porch.  It was definitely poured to add a bedroom.  There is no cracking in the ceilings or walls inside nor is there cracking outside either.  The roof looks good but you definitely see a slope there.  The doors all work well and I just replaced the windows about 3 years ago so they work well too.  The soil here is mostly clay but there is Palos Verdes stone somewhere beneath the clay (maybe 10 to 30 feet).  The slab has been unlevel since we moved here 18 years ago but has slowly gotten worse (maybe dropped an inch or so in that time.)   


As I posted the slab has sunk about 2-3 inches so I don't think I could pour over the old concrete as the concrete would be as high (or higher) then the sole plate so I think some type of jacking is the only option.

Thanks for the responses.

[jteneyck]

You need a structural engineer to answer the question.  I talked with a company that does helical piers when my porch sagged enough to crack the brick veneer.  The first thing they told me was that I needed a structural engineer to evaluate the problem and recommend a solution.  His calculations showed helical piers was a good solution and I ended up hiring that company.  Two piers, nearly 18 ft deep in our heavy clay soil were installed under the footer, and then the whole thing was jacked up until the porch and roof line were level again.  That must have been 7 or 8 years ago now; all good.  Not cheap, but much cheaper than a porch rebuild.

John