Chipped, crumbling, or cracking pool coping is not only an eyesore, it can also be a safety concern. Stepping on a broken coping stone could cause injury. Broken coping can also lead to much more serious and expensive damage to your pool if not repaired. Luckily, fixing broken or loose coping stones is a project that most pool owners can do by themselves.
Why is coping important? Not only does it provide an attractive finished rim for your swimming pool, it is also the capstone for your pool’s bond beam and brings your pool edge flush with the deck. Pre-cast concrete coping with a bull-nose front edge has been the standard for many years and is the most common coping you’ll find. Bullnose brick and flagstone are also very popular choices. Regardless of what your coping is made of all coping shares the same potential problems.
Many coping related problems can be explained by a failure of the expansion joint between the coping and the pool deck. If caulk is missing, cracked, or delaminated from one side of the joint then freezing water in the joint will put pressure on the coping and break the mortar that attaches it to the bond beam. Another possibility is that the expansion joint is not true, the joint doesn’t extend all the way to the ground without either side touching. The joint may have intact caulking but at some point the deck contacts the coping. Concrete and most other materials will expand and contract naturally with temperature changes, when the pool does this the deck will push on the coping and the bond beam causing them to separate. If you can wiggle the coping back and forth then it is likely you will have to pull the coping up. Remove the old mortar and reattach the coping to the bond beam with an anchoring like E-Z Patch 3, E-Z Patch 5, E-Z Patch 8, or E-Z Patch 22. Re-apply mortar (same as you used for setting the coping unless color is an issue) either side of the coping. Assess the rest of your expansion joint. If the caulk is in bad shape in other places it may be worthwhile to go ahead and replace all of it.
Caulking your Expansion Joint
To re-caulk, remove all of the old caulk from the joint as well as the backer rod you should find underneath it. The caulk should pull right out once you have a good grip on it. Use a utility knife to remove any stubborn caulk that remains. Inspect the joint for any stones or debris and make sure that the joint extends to the ground. If you find any place that the deck touches the coping you will want to remove part of the deck. If the problem area is small, you may be able to chisel away the deck. If the problem covers a wide area then it could be worthwhile to rent a demo hammer or a quick saw from your local hardware store.
Once the joint has had all the debris removed scrub the area with a stiff-bristled brush and a dilute solution of water and dish soap to remove any dirt or dust. Next, take backer rod and insert it into the joint until the top of the rod is at least ¼ inch deep. There are a few choices of pool caulk. Self-leveling pool caulk is runnier than traditional caulk and requires no taping on either side of the joint or finishing of the caulk bead. The caulk will flow, smoothing itself out. Self-leveling caulk will flow downhill so if your deck isn’t 100% level the caulk will pool in the low spots. For this reason you must use tape or putty on an open ended joint to prevent the caulk from running out. Semi self-leveling caulk has similar qualities to self-leveling caulk but is less runny. It will flow but not as much. For traditional caulk, called gun grade, you need to mask either side of the joint with tape before sealing the joint. Once the caulk is in the joint you need to trowel it smooth. The tape will prevent the caulk from adhering to your deck and coping, remove it before the caulk sets. All caulks are affected by temperature. The hotter the weather the runnier the caulk will be.
Crumbling Mortar Joints Between Coping Stones
If there is only a small superficial crack in your mortar it's probably not a problem. If a crack is large enough to allow water to seep in it can cause big problems down the line. There are a couple of possible reasons for a mortar joint to crumble. It could just be chemical breakdown, a bad concrete mix, or there could be directional force applying pressure to the area similarly to the causes of loose coping. If the coping is still firmly attached to the bond beam then you are in luck and likely only have to redo the mortar. Use a product such E-Z Patch 3, E-Z Patch 5, or E-Z Patch 8.
A piece has broken off of your coping or is simply missing. If you have the broken piece you can “glue” the piece back onto your coping using thin set mortar. First acid wash both of the broken faces of the coping and then rinse with plenty of water. When the coping is dry apply thinset such as E-Z Patch 3 to both broken faces of the stone, reattach the pieces, and sponge off the excess thinset.
If you are missing the piece you can use a repair medium such as E-Z Patch 5 or E-Z Patch 6 to sculpt the missing piece back onto your coping. Both of these products can be colored with masonry dye to match the color of your coping.
Typical costs for removal and replacement of pre-cast coping average $30 per linear foot. Add a few more dollars for bull-nose brick, and a few more than that for custom cut flagstone coping. To repair yourself, use a chisel and hammer and perhaps a quick saw to carefully pull up the loose stone. Carefully chip old mud off the coping stones and off the bond beam then reset the coping in a new bed of mud or thinset. Once set, fill in the mortar joints between the stones and then re-caulk as described above.When replacing or resetting a few coping stones bear in mind that the new coping stones will be much brighter than the old coping stones. Set Coping stones are difficult to pull up and clean without breakage. For this reason many people replace all the stones at once, even if not all the stones are broken. Especially if they're changing styles or colors.
Be sure to visit our Pool Repair Supplies page for your coping repair supplies