Last Updated: October 16, 2022

How To Caulk Your Inground Swimming Pool

Written By: Pool Care Guide

When was the last time you replaced the caulk between your inground swimming pool and the deck? Routine maintenance of your pool’s caulk can prevent serious damage to the structure of your cement or nylon swimming pool and the surrounding area. Old and flaking caulk looks unsightly but worse than that, it may be failing in its job to keep moisture out of sensitive areas.

Regularly replacing your caulk is a simple task that will result in a better-looking and longer-lasting pool.

Why Caulk Your Swimming Pool?

Pool caulking helps keep water out of areas where it can cause damage. But over time, cracks and holes can form and the caulk must be replaced. 

Just like caulk around your bathtub keeps moisture from rotting out your floor, pool caulk provides an important role in the structural integrity of your pool. 

As temperatures vary, your deck and pool expand and contract. To adjust for this, many pools have an expansion joint, which allows small changes in size without damaging the pool and surrounding area. Most newer pools have a foam strip installed that separates the deck from the pool for this purpose.

The joint is sealed with caulk to prevent dirt and moisture from entering the seam. Dirt and debris can fill the gap and prevent the joint from naturally expanding as needed. And if enough water gets into the expansion joint and cools, it can cause severe structural damage.

Under the heat of the sun, cement expands. And ice expands with such force that it can break cement, stone, and even steel. Repairing that sort of damage to the pool or deck can be extremely costly.

It’s crucial to check your pool caulk for cracks and signs of wear to avoid damage from expansion. If you live in an area where the temperature fluctuates, you should be extra vigilant.

If the caulk looks old or brittle, it’s time to remove and replace it.

How To Replace Pool Caulking

Caulking your pool is a fairly straightforward process for most DIYers, but it can be strenuous. You’ll need to spend plenty of time on your knees, bending over your work. You should work carefully to ensure the caulk is even and clean looking for the best results.

If you have doubts about the process, consider calling a professional.

What You Need

You don’t need advanced or expensive equipment to caulk your pool. Just make sure you have the following materials before you begin:

  • Pool caulking (semi-self-leveling works best)
  • Large quart-size caulking gun
  • A leaf blower or pressure washer
  • Foam backer rod
  • Damp cloth
  • Flat cardboard
  • Sand (optional)

A Step-by-Step Guide to Caulking

Now that you have your materials, it’s time to begin caulking. 

Choose a dry, temperate day between 50 and 80 degrees. Extreme heat and cold can interfere with the drying and hardening process, not to mention making this simple task much more unpleasant.

For the best results, don’t rush the caulking process, even if you’re sick of being on your knees. Not only will a rush job look bad, but the caulk may not do its job to prevent moisture from entering the seam.

  1. Use a leaf blower or pressure washer to remove any leaves or debris around the area you are about to caulk. 
  2. Scrape off and remove the old caulk that looks brittle or old. A sharp razor knife works well to cut off old pieces of caulk. Much of it can also be pulled up by hand.
  3. Blow off any remnants of old caulk and clean the area. The caulk will better adhere to areas without debris.
  4. Make sure the area is dry.
  5. Lay the cardboard flat and straight next to the area where you are working.
  6. Place the foam backer rod inside any portions of the crack where it is missing or damaged. The foam backer rod should be about half an inch from the surface.
  7. Insert the caulk in the caulking gun and snip off the end.
  8. Squeeze the trigger and run a bead of caulking over the foam backer. The caulk should be as even as possible. Fill the joint, but don’t allow the caulk to overflow.
  9. Wipe away any caulk that dripped in a place it’s not needed. Mineral spirits or xylene work best for cleanup.
  10. Double-check the area to make sure you haven’t missed a spot.
  11. If desired, sprinkle sand over the caulk to better match the color of a concrete pool or deck. 
  12. Allow the caulk to completely dry and harden for about 24-48 hours. Avoid the area as much as possible.
  13. Add another layer of caulk following the same steps if necessary.

Your caulk will be somewhat visible when you’re done, so make sure you work carefully. Smooth, even distribution will make the finished product look better.

More importantly, consistent application will work better to prevent moisture from entering any crevices. As the caulk dries, it will fill any nooks and crannies and keep water out, at least until it needs replacing again.

Do I Really Need To Bother?

Well, yes. It might seem like a pain, but regular maintenance of your pool’s caulking could save you thousands of dollars in more substantial repairs. 

You should replace the caulk every five to ten years and regularly inspect it for signs of wear. If you live somewhere with extreme temperature fluctuations, be extra vigilant about regularly replacing your caulk. And if you have kids, guests, or dogs who frequently splash outside the pool, you may also need more frequent upkeep.

Final Thoughts

If you can’t remember the last time you replaced the caulk, it’s probably time to pull out your caulk gun. All things considered, it’s a pretty easy and inexpensive chore. Putting it off year after year might be appealing, but you’ll regret it when cracks and distortions to your foundation begin to form.

So watch your caulk for signs of wear and tear. When it starts to look old and flaky, it’s time to replace it.

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