Question About Paving Stone Installation

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poolneophyte

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Jul 1, 2009
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Long Island, NY
Our pool has been filled and operational for almost a month now and we are getting quotations from contractors for a paving stone deck around the pool. I have been getting different opinions from contractors on how to set the pavers around the pool. Some companies pour a concrete slab which is tied into the pool rebars (which are currently bent flat against the ground) and others use a recycled concrete aggregate (RCA) base. I was told that at least one of the paving stone manufacturer's (Cambridge) void their warranty if the pavers are set on top of concrete.

I am leaning towards a contractor who will excavate around the pool and install a 6" RCA sub-base and compact it to 95% density. He then sets the pavers on top of a 1" layer of blue stone dust and then fills the joints in with fine sand. I am worried about future settlling around the pool. The other contractors who pour a concrete slab as the base state that the slab is supported independant of the excavated earth around the pool and will not settle. By the way, the pool builder also installed sonotubes around the pool to support the pool deck from undisturbed soil below.

So, I am looking for opinions on the best method of installation. Also, how long should I wait for the ground to settle if I don't go with a concrete sub-base?
 
I would not place pavers on top of a concrete slab in an environment where freezing occurs.

Take a look at this website:

http://www.hanoverpavers.com/index.html

Even for their commercial applications for vehicle traffic, they don't recommend anything other than compacted stone bases. Water needs to get away from under these surfaces since they are not impervious.

In NY if water gets under the pavers it will likely get trapped between the pavers and concrete. When it freezes, your pavers are going to move EVERYWHERE.

Of course once the base issue is settled, I would also not recommend regular sand between the pavers. I would recommend Polymeric Sand.

http://www.groundtradesxchange.com/pave ... c_sand.htm

Once swept in and installed properly, polymeric sand sets up very hard- like concrete so that it won't get tracked into your pool or house and you won't have weeds in your nice new patio.

If it were mine, I would go with a STONE base, POLYMERIC sand, and I would install myself.

But it's not mine and I'm just a stranger on the internet- so a good contractor is probably the most important part of the whole job.
 
Hi. Im fron Scranton Pa. The only way contractors even do pavers around here is on a concrete base. I just had 900 sq ft of them installed on concrete with the polymetric sand .. My friends both have paver driveways with concrete bases and havent had any movement in 3 years , even though we do get freezing temps. Like anything, if not installed properly , youll have trouble. give me your email and ill send ya some pics. cant figure out how to post pics on here. Chuck
 
Thanks for the responses. It seems that there is a difference in opinion about which installation method is best. I have talked to several local contractors and can't seem to get a definate answer about the installation of a concrete slab as the sub-base for paving stones. I had one contractor provide a ten year guarantee on his installation but the pavers must be installed on top of concrete. This same contractor ties the slab into the concrete pool walls and supports the slab from undisturbed soil using sonotube piles. Basically, even if the soil settles under the slab, the pavers will not settle.

Still not sure what to do.
 
I've got pavers and they are set on crushed stone. Since most of the backside of my pool had to be built up with fill dirt, I have had a little bit of settling. Correcting that problem has been pretty easy though, pull up and area of pavers, put a bit more crushed stone down and put the pavers back in. Much easier than dealing with cracks in a concrete decking.
 
This same contractor ties the slab into the concrete pool walls and supports the slab from undisturbed soil using sonotube piles. Basically, even if the soil settles under the slab, the pavers will not settle.
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I would certainly defer to this guys knowledge but I question that the support tubes will prevent cracking. Concrete has little tensile strength. Once the soil settles away from it, it cracks. I am also not clear that tying into the pool is helpful. Almost every pool built is intentionally constructed seperately from the decking because the expansion and contraction is in different directions........that's why that 1/2" bead of caulk is around most pools where the coping meets the deck.

That said, he's in the business as a profession and if he guarantees concrete for 10 crack-free years he seem confident in his methods.

I'm personally with Crabboy........your dirt will settle and not using slab concrete makes for easy compensation as it does.
 
I agree that we would probably be better off without a concrete slab for maintenance reasons. My wife and I are discussing if we should let it settle until next spring before we do the paving stones. Our entire back yard is presently unusable and I would like to get it back into shape as quickly as possible. I went to a masonry yard over the weekend and was speaking with the daughter of the manager who agreed that it would be best to let it settle until next spring before we do anything.
 
I'd be concerned about tieing the slab (if you go that route) to the pool! Pools and decks expand and contract at two different rates, and tieing one to the other would not be something that I would do. I have seen many skimmer failures when they are encapsulated in the deck instead of blocked out as part of the pool (like they are supposed to be). The same would be true in this case.

I would think that the road base and sand combo would be ideal, and the great part about pavers is that they can be lifted out and reset if they need to be. If you have highly expansive soil then no matter what you put down you will get movement.

Good luck!

Bruce
 

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You're asking about "paving stones." Are you talking about pavers or are you talking about natural stone like flagstone? I think you're asking about pavers.

I just got through researching and installing about 600 sf of flagstone under my deck adjacent to my pool. Filling the dang joints was the biggest headache.

I'm a structural engineer and deal with retaining walls a good bit. You said you were considering tying the slab to the pool. Is this a shotcrete pool? In retaining/basement wall design on buildings it's very common to tie the slab to the wall to stabilize it. You also will typically reinforce the slab with extra rebar because the soil behind the wall rarely gets compacted adequately. The extra steel helps the slab span over the softzone. If you have a liner pool then I'm not picturing what this rebar is attaching to on the pool.

You mentioned sonotubes. It almost sounds like they're drilling shafts at some spacing then placing a slab to span from shaft to shaft. As long as the slab is adequately designed then this sounds like a dang good system. This is real common is areas with pool soils for buildings. I've done many projects where you do this. You basically act like the soil isn't there. If it settles, who cares. This is going to be more expensive, but your slab shouldn't move. As long as the paver vendor is good with his product on a slab then you should be good to go. I guess my only concern would be with how they manage water drainage to prevent heaving in winter. I think the last job I designed in NY we had something like a 40" frost heave depth to contend with so you're slab will definitely freeze.

Finally, movement was mentioned in several responses but I don't recall people talking about which type of movement. I don't think I'd be worried about thermal movement. The reason concrete is reinforced with steel is that they both have almost identical coeff of thermal expansion, ie, they move at the same rate. Also, concrete is as big as it ever gets when it is placed on site. It shrinks due to the loss of moisture when it cures. In the summer, it won't expand past that initial volume. I don't think I'd be worried about load movement. THe water pressure is pushing the walls out and the soils pressure is resisting this. There shouldn't be much movement in the horizontal movement. That leaves settlement movement which was discussed above.

Did any of that help or did I just muddy the water?
 
So I know this is an OLD thread but it so happens I am also on Long Island and am getting estimates for Cambridge Pavers in my backyard around my IGP. I have 2500 SQFT of pavers that I will need. I have had 4 estimates. 2 of them said 5 ft of concrete around the pool and the rest is RCA. The other 2, was all RCA (no estimate yet). What did you wind up doing, and why, and who did you use and were you happy? The one guy who I liked was the MOST expensive so far and he wanted to do ht concrete / RCA combo (it was $30k). I have not gotten back my estimates from the ones who only use RCA yet. I do have 2 friends who are in the business. Both say I should used either ONLY concrete or the concrete RCA combo. Cambridge said just the RCA is what should be used.
 
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