Patching Coping Stone
What You'll Need:
When you build a pool and deck, you've got two separate concrete structures that can be joined together in any of four ways.
One of the original ways is to build the pool wall up to about the same elevation as the top of the inside edge of the deck and leave a small gap between deck and the top of the pool wall. You then cover this gap and the top of the pool wall with a decorative, cement coping stone. By cementing the coping stone to only the top of the pool wall, you're letting it float over the gap and deck edge. Built correctly, this is simple and effective blend of structures and will last decades without problems.
If the outside edge of the copng should somehow become attached to the deck surface, either by using a non-flexible gap filler, tile or a textured surface material (like Kool Deck or acrylic knock-down) that touches both deck and coping stone surfaces, the coping stone can no longer float and problems arise.
Now, any deck settlement or pool expansion pressure gets transfered to the coping stones and, being decorative and not structural, respond by cracking and splintering. And, sometimes they just seem to fall apart for no particular reason whatsoever.
Replacing coping stones is a simple enough process (and is covered on the Pool School PRO CD) when the stones are still being manufactured and readily available. But what happens when you have a cracked coping stone and they aren't making that particular size or style anymore?
This is a much easier job when the pool is drained, but do-able, with patience, in a filled pool. Understand that you cannot drive masonry nails into coping stone or grout joints to attach formwork so use the adjoining stones to reference form and elevation.
The basic repair material is color matched sanded tile grout. Buy it in the 25 lb. bag and get it from a tile or hardware store or the Lowes acrylic- fortified grout. Home Depot tile grout is noticeably grainy and needs a white cement (unsanded tile grout) boost to adhere properly.
Remove any loose material and hose the area well. To prevent rust bleed-thru, any exposed steel reinforcement rods should be spray painted or removed. Sponge cement bonding agent over the area. Remember that the bonding agent dries clear, so be generous in your application without causing puddling.
Mix the grout to a peanut butter consistency. Using the profile of the adjoining stones, roughly trowel the grout into shape and (depending on the length of the coping nose (what extends out into the pool) and you may have to form it by hand. Give the material twenty minutes to begin to set.
(photo above left) If you're having problems forming the nose (material falls into the pool), add a little dry cement to your mix and stir well and often. Keep the mixing bucket out of the sun and build out the nose as the material stiffens.
A pocked surface can be duplicated by troweling salt (pool or ice cream salt) flat into the surface and allowing the surface to set. Come back the next day, rinse the salt crystals away and Voila! A salt texture.
This particular finish featured small flakes duplicated by using an over-sized salt shaker to distribute black and white flakes sold in paint stores to decorate garage floors. The surface was troweled smooth, swiped lightly with a damp sponge for a little non-skid texture and the flakes applied while the surface would still absorb them.
Clean up comes an hour later with a weak acid (1acid to 5 water) sponge wipe, a solution that's also effective in removing cement from your hands so long as you have a hose handy.
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