Paver patio over slab and grading

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Old 09-05-16, 05:51 AM
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Paver patio over slab and grading

I just purchased a house on Friday. we had noticed that the patio is not graded well and I had it on my list for top 5 projects. However, over the weekend I started looking at it more and found out that there us actually what looks like a 4 inch slab under the pavers.

Ideally I would jackhammer up the slab and do it correctly from the start but it's just not an option before winter.

Any suggestions as to what to use the level off and then grade away from the house on top of the slab that will move water before I put the pacers back down? Thankfully the pacers are not mortered into place.

Any suggestions are appreciated.

Adam
 
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Old 09-05-16, 06:16 AM
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How far out of level is the concrete slab? How much height/elevation do you have to work with before the pavers are too high like where they meet a door?
 
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Old 09-05-16, 06:21 AM
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Thank you for the reply. I have a lot of hight to work with. The patio is down about 2.5-3 feet from the main level.

I would say that I need to bring the lowest point up no more then 3 inches.
 
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Old 09-06-16, 09:04 AM
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Not ideal but the right thing to do short of removing the slab is put a compacted base on top of it with the necessary slope and then a 1" layer of bedding sand.
 
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Old 09-06-16, 10:02 AM
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I agree. I would do the leveling with a base layer no more than 4" thick. Level it and compact with a plate compactor. In some areas your base might be 4" thick while in others it might only be 1".
 
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Old 09-08-16, 06:04 PM
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Thank you both.

Would there be any benefit to using one of the epoxy based liquid leveling agents to create a level base to start with as they are water impermeable? And then use the compacted base to create the grade? Or simply stick with the base and sand?

Regards,
Adam
 
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Old 09-08-16, 06:57 PM
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You don't want a level base, you want a slope away from the building.
 
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Old 09-08-16, 08:45 PM
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Understood.

Right now the slab is sloped towards the house for about 4-6 feet of the total 15 foot depth. So with the solution you suggested I would be using the compacted base and sand to create the grade/slope away from the house. So the closer to the house you get the thicker the compacted base/sand layer gets in order to maintain the slope.

I guess what I was asking was is it worth using a leveling agent to essential make the slab flat vs sloping in the direction of the house as step one.

That way the compacted base and sand layers do not need to be as thick in order to maintain the negative slope.

Not sure if that makes any sense sorry typing on my phone in an airport.
 
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Old 09-09-16, 07:49 AM
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Do you have a basement? Do you have water problems in the basement?

If you are having water problems in the basement I might consider doing an over pour on the concrete slab but that's a long shot at best. Some small amount of water will get through the pavers but the majority will run off if you grade/slope it properly and that is enough for most/all applications. Consider that most don't have a concrete slab underneath to act as a water diversion.
 
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