Correcting the pitch of a concrete slab

[Daniel Prince]

One of the concrete slabs forming our back porch is pitched incorrectly. It is pitched towards the house so that we get about an inch of standing water against the house every time it rains. What is the easiest way to correct this problem?

I have seen a product called "concrete resurfacer" in the Home Depot advertisement. Could we use this stuff to build up the concrete near the house so that the rain runs away from the house? Is there something that would be better? Thank you in advance for all replies.

[ameijers]

If you are getting ponding an inch deep, that is beyond what the resurfacer stuff is intended for. Yeah, you could do it, but it would take layers, be expensive, less than durable, and look like crap. If there is enough clearance at door, you could pour another 2-3 inch slab over the whole patio, using anchor bolts and wire mesh to tie it all together.

Did slab sink near house, or (more likely) heave up at outer edge due to frost/bad drainage/poor footers? I'd look in concrete section of yellow pages, and have a mudjacking company come out for an estimate, and see if they think they can fine-tune reality for you. Compare their estimate to the correct fix of jackhammer and replacement with a properly engineered slab.

aem sends....

[Dennis J Sunday]

I agree with last post. Resurfacer has its limitations, which it sounds like you are beyond. You might be able to repour a portion of the slab.

-- Best Regards, Dennis J Sunday Home Inspection Systems

[EvoDawg]

There's not really much you can do but jack it out and replace it with the right pitch. If you leave it the way it is your asking for big trouble. All that crap you get at Home Depot is just a temporary fix that probably won't last a year.

Good Luck, Rich California Licensed General Engineering Contractor.

[Tom Baker]

ameijers brings up an important point: You've said one end of one slab is lower than the other. How does this compare to the other end of the same slab and to the house? Is the incorrect pitch the result of heaving of the outer end, sinking of the low end, or bad work?

The fix would depend on the cause of the problem and the room available to "play" with.

Tom Baker AIA

[rb608]

Rich, What do you think about roughing up the top surface & pouring a sloped couple inches on top? (Assuming Daniel can live with a raised slab.)

Joe F.

[RB]

If the slab is moving then this won't be any more than a band-aid. The root cause must be determined and fixed first.

RB

rb608 wrote:

[raven]

Mud Jack it. A pro will come in, drill a few holes in the slab, pump high pressure slurry concrete underneath the slab untill it's pitched correctly, then plug the holes. A small cost, a permanant repair, and yo'll never have to worry about it again.

Yes. You can use topping cement, and if you work hard at it you can get a good effect, but then the topping cement will be subject to spalling, as it's not going to be as strong as the original slab... If you positively can't get it jacked, say you _have_ to do it yourself, then this is the way to go, but it's definetly a poor second to geting the slab jacked.

The only other option is to bust the whole thing up, correct the bed (which has probably subsided) and re-pour to the correct grade. Way too much work.

Get it mud jacked.

John

[EvoDawg]

Unless concrete has something in it like crushed rock 3/4" it will fall apart. With only 2" the expansion will also cause it to crumble. I've seen this type of fix only to tell the customer it will not work and him calling me back months later to replace the entire slab or cutting out a portion and repairing that section.

Setup is 90% of the work. Most weekend warriors and fly by night so called contractors don't understand that concept. You get what you pay for! One of the first things you learn as a contractor and inspector is water grade drainage away from the house or foundation.

Rich

[MaxAluminum]

He could have a company come in and mud-jack the slab to the desired height. they would drill a few holes in the slab and fill them afterwords. The job would be done in less than a day. It costs far less than replacing, but perhaps more than the OP wants to spend. It is worth a call because the process is very effective.

[Chris Lewis]

As long as it's not _still_ moving. Hopefully the pro can figure that out.

[Daniel Prince]

I can not be frost heaving because we are in the Southern end of Los Angeles County and the ground never freezes. I think it was just bad work.