Updated 21 August 2026 · written by the crew that installs it
A chalking Kool Deck cannot be repaired in place. The acrylic and cement topping has lost its bond to the slab, so anything coated over it fails with it. It can be resurfaced: the failed topping is ground back to sound concrete, cracks are treated, the slab is primed, and a new seamless layer is poured on top. In South Florida that starts at 8 dollars per sq ft installed, takes 1 to 3 days on a typical deck, and needs no demolition and no dumpster.
Kool Deck is a registered product of Mortex, and for fifty years it was the default pool deck finish in Florida. It is also the surface most often failing right now, because the ones poured in the eighties and nineties have reached the end of their life at the same time.
These are different failures with different answers, and you can diagnose both yourself before anyone quotes you.
Chalking. Drag a thumb across the dry surface. If it comes away with fine pale dust, the binder in the topping has broken down under UV. The texture is washing off a little more with every rain. The slab underneath is usually still fine.
Delamination. Tap across the deck with a coin or a screwdriver handle. Sound concrete rings solid. A hollow, drummy note means the topping has released from the slab and is sitting on air. Press hard on a hollow area and you may feel it flex.
The tape test. Press a strip of packing tape firmly onto a clean dry patch and rip it off. If it lifts a layer of the topping, the bond is gone.
Chalking on a sound slab is the easy case. Widespread delamination means more grinding, and a slab that has settled differentially or is contaminated with oil or an old sealer may not be worth resurfacing at all. We say so at the estimate rather than after.
The instinct is to buy a bucket of deck coating and roll it on. It fails for a simple reason: a coating is only as good as what it is stuck to. If the Kool Deck under it is chalking, the new coating bonds to loose dust, and the whole thing lifts in sheets within a season or two.
The same applies to a second layer of Kool Deck over the first. The product was designed to go onto fresh concrete, not onto a failed topping.
Grind the failed topping back until the surface rings solid everywhere. Cut out and rebuild any crumbling edges at the coping and the expansion joints. Treat and bridge cracks so they do not telegraph through. Prime the slab, and check it for trapped moisture first, because South Florida slabs sit on a high water table and a slab giving off vapour will push a coating off.
Then pour the new surface. Poured rubber goes down at 0.4 to 0.75 inch and is soft, permeable and cooler underfoot. Stone carpet goes down at 0.3 to 0.6 inch and looks like natural pebble. Both are seamless, both drain through, both go over the slab you already have.
From 8 dollars per sq ft installed, with the number depending on how much grinding the old topping needs and how many colors you pick. A typical deck is 1 to 3 days, walkable in 24 to 48 hours and at full strength on day 7.
Compare that with the alternative most people are quoted: tear out the deck and lay pavers, at 25 to 40 dollars per sq ft, 2 to 4 weeks, a dumpster in the driveway and a permit in most Broward cities.
Kool Deck was sold on staying cooler than plain concrete, and it does. But by the time it is chalking it has lost the texture that did the work. On a 91 degree afternoon a bare concrete deck hands your foot about 134 degrees. A light sand poured rubber deck hands it about 99. The full table with the arithmetic is here.
Can you resurface over Kool Deck without removing it? Only where it is still sound and bonded. Anywhere it is chalking or drummy it comes off first, otherwise the new surface inherits the failure.
Do I need a permit? In most Broward and Miami-Dade cities a like for like resurfacing does not trigger one. We check your municipality before the work and say so in writing.
Will it crack again? Cracks come from the slab, not the surface. A poured elastic layer bridges hairline movement instead of telegraphing it, which is why the same crack that returns through paint every year stops showing.
Is Kool Deck still made? Yes, by Mortex. We are not affiliated with them and we do not install it. We name it here because it is what most South Florida decks are surfaced with, and it is the thing people are trying to fix.