Changing the slope of a concrete slab
#1
08-31-09, 07:08 PM
Changing the slope of a concrete slab
I have a exterior concrete slab, half of it slopes towards my house so it is high in the middle of the slab. I'd say from the ridge to the house it is about 1" for six feet. What is the best way to fix the slope so water runs away from the house?
#2
09-01-09, 01:27 PM
Did the concrete settle near the house, but not out further? Is there a crack or joint at the ridge, or was it just badly finished so it sloped the wrong way? If it settled, then you can call a slabjacking (mudjacking) company. They can lift it up to it's original elevation.
#3
09-02-09, 09:28 AM
It was just a bad finish. No crack on the ridge. I think originally it was going to be a covered area. So maybe slope was not really taken into consideration.
I think I need to add in @ 2.5 inches at the house and slope it back to the ridge. What would be the best way of doing this. I read where I should clean the surface then just use quikrete for the first 1.5 inches then use some kind of concrete patch to finish off the last inch.
Should I do more to prepare the slab surface for the first pour? Is there anything I need to do so the new pour will adhere to the slab?
I think I need to add in @ 2.5 inches at the house and slope it back to the ridge. What would be the best way of doing this. I read where I should clean the surface then just use quikrete for the first 1.5 inches then use some kind of concrete patch to finish off the last inch.
Should I do more to prepare the slab surface for the first pour? Is there anything I need to do so the new pour will adhere to the slab?
#4
09-03-09, 02:35 AM
It can be done the way you suggest, but it will probably look like a patch job and the longevity of the repair is questionable. Prep is a big part of the battle. At minimum a VERY thorough pressure washing will help, but I would do an acid etch followed by the pressure washing. Before pouring, apply a bonding agent such as WeldCrete or similar. A patch that is over an inch thick will require stone aggregate in the mix, so I would use something like regular quikrete to get from the 2.5 inches down to about 1 inch, then another product (ask someone where you're buying what is available) to feather from the 1 inch to nothing. Follow this with something like quikrete resurfacer over the entire patio so the color matches everywhere. That's the DIY version.
To do it the best way, rip it out and have it repoured correctly.
To do it the best way, rip it out and have it repoured correctly.
#5
09-03-09, 09:11 AM
thanks for the info. This was very helpful. I will look into acid etching and bonding agents/patch available here locally.
I agree it will look like a DYI project but a good interim measure until we can decide what we want to do with this area.
I agree it will look like a DYI project but a good interim measure until we can decide what we want to do with this area.
#6
09-17-09, 11:55 PM
I would recommend Sikatop 122. It can be applied from 1/4" to 1" and you can add peagravel to it to go thicker. It is a little expensive, but will last much longer than a bagged concrete mix. You do not need a bonding agent, but you will have to sacrifice one bag to mix as a slurry and brush on to prime the surface. As Pecos said, a good etching will only help the bond.
Good luck.
Good luck.
