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I want to lay down a natural stone patio over an existing concrete patio around my in-ground pool. I live in New York and I am worried about the new patio lifting from the frost of winter. Do I lay a bed of sand or stonedust or dry mortar over the concrete? Im trying not to tear up the old concrete and do I need to worry about the chlorine water from the pool affecting the mortar of the new patio? Any help would be greatly appreciated.
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I'll offer this thought, not to dissuade you from natural stone, but to make sure you're aware of an alternative. If you haven't already, check into "polymer overlays". You could get a stamped concrete look over the existing concrete, giving you the look of stone, granite, brick, etc without the maintenance of real stone with mortar joints, etc.
Only other thought is, with sand/stonedust I'd worry about dragging it into the pool be/c it's loose and would blow or stick to wet feet. That said, we're doing an outdoor hot tub of concrete and using a natural rock surround, set in cement and grouted. Still, nowhere near pool size and traffic.
Jim
*b WBA At Your ServiceNatural stone. Do you mean flagstone ? This is commonly used for this application with minimal concerns about pool chemicals. The installation is a serious job. The flagstone comes in varying thicknesses as a product. What I mean is that when you choose the 1" thick flagstone ( as opposed to the 2" thick material), you will get material that varies in thickness from 3/4" to almost 1 1/2". That's just the way it is. Stone like this is a natural product that doesn't split uniformly. This complicates the laying process. Our mason generally lays this material over concrete slabs (like what you have) in a portland cement and sand mix that is mixed with water and sometimes a latex additive to assist bonding. The mix is kept crumbly dry. The backs of the stones are buttered with a pure portland cement/lime creamy mix. You need to examine all of your stones looking for the thickest material and figure that you will need at least a 1/2" to 3/4" thick setting bed under your thickest stones. Obviously the thinner ones take much more than that. The stones are leveled as they are laid doing one at a time, setting it checking for level and how it meets the stones next to it and most importantly that the stones are fully supported by the mud below. You must pick up and relay each stone sometimes a few times. It's not like laying uniform thickness ceramic tile. It takes time. And then so does all of the cutting. A diamond wheel in a 4 or 5" grinder will do the job. You must have control joints in the flagstone that line up with the control joints in the concrete below. Consider what you will do at the edge of the pool where the stones overhang the edge of the concrete coping. The edges of all of these stones have a different edge treatment than the stones bought out of the crate which come with a sawn edge. You will probably prefer the look of a rough edge that comes from snapping the product in a special cutter or hand chiseling or spalling with an acetylene torch. Also consider at this edge you will notice that the stones are not all uniform thickness unless you hand select stones for this purpose. One last thing, will this elevation change of about 2" to the top of your pool adversely affect the step heights of your pool steps or ladders ? Don't make that last step out a doozy or you better keep your homeowner's policy handy.
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I want to lay down a natural stone patio over an existing concrete patio around my in-ground pool. I live in New York and I am worried about the new patio lifting from the frost of winter. Do I lay a bed of sand or stonedust or dry mortar over the concrete? Im trying not to tear up the old concrete and do I need to worry about the chlorine water from the pool affecting the mortar of the new patio? Any help would be greatly appreciated.