by Sean Griffin, September 4, 2009
Pool owners often overlook caulking the joint between the pool coping and the pool deck. Because of the time needed to allow pool deck and coping to shift and allow proper curing time, pool builders often refrain from including caulking your pool when building operations are complete. When the expansion joint is not caulked you are at risk of damage.
The expansion joint allows for the deck and pool to expand, independently - that is, without hitting each other. Without a "True" expansion joint, all the way through to the earth, when the deck expands, it can crack and break the top of your pool wall.
The pool caulking is designed to prevent water from entering the expansion joint. Water can erode the supporting earth beneath your pool deck. Damage can also occur during the winter months as water freezes and expands and can lead to structural damage. Coping stones can become loose and/or crack, tile line can crack and lead to fallen tiles, and the bond beam of pool structure can become compromised.
The bond beam is the top section of pool wall that holds the coping for your pool. When caulking is forgotten or is in need of a repair it can often lead to major renovations that can include removing coping stones, building up bond beam, resetting stones and re-tiling the pool. The best remedy is to make sure your expansion joint is properly caulked.
When caulking your pool expansion joint follow all the instructions set forth by manufacturer to achieve the best results. The majority of the work will be in the preparation. All debris and moisture will need to be removed from the joint. You can achieve this by using a brush, shop-vac, leaf blower, etc. I typically use a portable torch to go along the perimeter of pool and burn out any moisture and any debris. Sunlight will also help dry up any moisture in joint as will a heat gun or hair dryer.
There are several options when choosing your pool caulk. Different manufacturers and different kinds of pool caulk will depict the exact prep work needed for job. The three most common pool caulks come in self-leveling, semi-self leveling, and gun grade (used by professionals). They all have a different viscosity and your selection should reflect your skill level and the job you are undertaking.
When using gun grade pool caulk you will need to tape off either side of the joint (masking tape works best). You will also need a hand tool, typically a trowel, to put a finish on the joint and work caulk down into joint. Remember to use backer rod to fill voids so as to prevent excessive caulk usage. Backer rod also gives caulk a place to sit on as it cures.
With self-leveling and semi self-leveling caulk, the pool caulk will settle at the lowest point. This is ideal for 100% even joints that can be sealed off to prevent caulk from running out of joint. Backer rod is recommended even more, to fill any void and help form the joint. Most importantly, if foam backer rod is not used, the caulking will just run down into the joint, as it is very runny. Chilling your caulk, and applying during a cooler time of day will make it less runny.
Caulking your pool prevents damage from ice expansion during the winter, and prevents the joint from filling up with debris over time. If the joint fills with debris and sand, then movement of the deck will also move the coping, eventually loosening the coping. More advanced damage breaks the top part of the pool, under the coping, and through the tile line. A very expensive repair. So, do some preventative maintenance, and caulk your pool!