Pool Caulking Damage - Repair or Replace?

Repair or Replace Pool Caulking Damage?
by Rob Cox, August 28, 2019

Repair or Replace Pool Caulking Damage?

Before and After pool caulking by Caulking Unlimited, Fred., Md.


Now is the time to get those pools caulked before we are once again in winter's icy grip.

For inground pools with coping stones or brick coping, it is very important to keep your expansion joint caulking in good repair, to keep the joint clear and free from debris and water, both of which can wreak their own forms of havoc.

Without caulking covering the expansion joint, leaves, dirt and sand will fill the joint over time, removing the room for expansion of the deck and pool in warm weather. In time, the vertical pool wall will lose the fight against the horizontal pool deck, and cracking through the beam of the pool, at the tile line could be the eventual result of not maintaining a true and clean expansion joint around the pool.

Another reason for caulking around the pool is to prevent water from freezing in the joint during winter, expanding inside the joint, putting pressure on the pool wall or the back of the coping stone. Loose coping stones and popped tiles can result. Over years of freeze/thaw cycles, ice in your expansion joint can possibly lead to an expensive repair.

example of FROST HEAVE, notice the deck is raised over 1 inchA third reason is to help stop frost heave by blocking water. Frost heave is when the wet ground under a slab of concrete freezes and lifts the slab, as shown in the image below. See an earlier post on the topic of frost heave on a concrete pool deck.

And that is the topic of the day - pool caulking repairs. The caulking joint around the pool is an important part of an inground pool. The caulk covers an expansion joint between the pool and the deck, to allow them both to expand and contract independently, during temperature swings.

How Long Does Pool Caulking Last? 

Generally speaking, it's about 5 years before enough movement and deterioration will need repair or replacement. Sections of your caulking run can last up to 10 years, so it begs the question - Repair or Replace?

To replace just a portion of the caulking, you can simply cut out the old sections with a razor knife, and fill-in those areas with new caulk. The color will not be exactly the same however, even if you use the same caulk and color. The older caulk will have a faded appearance next to the new caulk - but, if you only need to do 10 feet, why do the entire pool? 

DIY Caulking vs. Professional Pool Caulking

An experienced caulk professional can caulk circles around any homeowner. Fast, clean and smooth. If you say to yourself, "I've caulked my bathtub, how hard could it be to caulk the pool?" It's not hard, but it is a much larger bathtub, and is a bit more complicated.

Caulk Pros generally use what's called Gun Grade caulking. Mixed on site, it is troweled into the joint by hand to a consistent depth and angle. It's also the only way to caulk vertical joints or a joint where the coping and pool deck are not at the same level. This method is best left to the pros, in my opinion. It's difficult for a novice to tackle, especially with brick coping, or when the pool deck and coping aren't evenly lined up.

Poolcenter's pool caulking suppliesHomeowners can more easily use self-leveling pool caulk, such as our popular Vulkem 45 SSL caulk shown here, available in Grey, White and Tan colors. After cleaning the joint and installing backer rod foam to keep the (costly) caulk from running down, a large caulking gun (29 oz) delivers the semi-runny caulk into the joint, where it self-levels and bonds to both sides of the joint - pool deck and pool coping. Self-leveling caulk is easy to apply, but won't work for angles or vertical joints.

If you want to have your pool professionally caulked, search online for swimming pool caulking, and you'll find some local companies who will give you a price per linear foot, to remove and replace your pool caulk. The average cost for a company to remove/replace pool caulking is around $6-7 per linear foot, more if the joint is over 1" wide. Most pool perimeter expansion joints are in the 100-130 linear foot range, putting most pools in the $600-$900 range.

If you want some DIY pool caulking however, read this post on how to caulk your pool's expansion joint. With a spare sunny Saturday, you can caulk your own swimming pool expansion joint and could save $500 in the process.

Pool Caulking Tips

  1. foam backer rodMeasure your joint width and depth carefully, to buy enough caulk.
  2. Use a razor knife carefully to remove all old caulk.
  3. Scrub the joint with a mild soap to remove any grease.
  4. Blow the joint dry with a large leaf blower, or compressed air.
  5. Insert foam backer rod to a precise depth, in spots where missing.
  6. Wear old clothes, move around the pool slowly with a large piece of cardboard.
  7. Lock up the dog and cat, and maybe the kids - for the day. ;-)



  1. Be sure that the joint is very dry before caulking, and check for a dry weather forecast.
  2. Keep a few 1/2" pieces of twine handy for any 'runners', voids where the caulk starts to run through.
  3. Remember that self-leveling caulk will seek the lowest level, or the lowest side of the pool or deck.
  4. Keep paint thinner, goof-off other solvent and a rag handy, to clean-up hands or spills quickly.
  5. Taping the deck is not necessary and will not stick evenly, except on finely cut stone.

 Caulking Unlimited - before and after pool caulking repair

- Rob


Thanks to Caulking Unlimited of Frederick, MD for these great before and after photos of their pool caulking skills.