Sealants & Waterproofing

Expansion joints are the most overlooked part of a pool — and the cheapest single thing you can keep up with that prevents catastrophic damage. The joint between your coping and deck exists for a reason: deck and coping move at different rates as temperature changes, and without a flexible joint between them, something has to crack. In our Mid-Atlantic freeze-thaw climate, that something is usually the bond beam at the top of your shell.

We re-seal expansion joints, deck cracks, and masonry gaps for pools across PA, NJ, and DE using a self-leveling polyurethane mastic engineered specifically for submerged-edge masonry applications.

What we seal and why

• Coping-to-deck expansion joint — the most important joint on the pool. Failed mastic here lets water down behind the coping and into the bond beam.
• Deck control joints — the saw-cut grid that prevents your deck from cracking randomly. These open up with age and need re-sealing.
• Coping-to-tile transition — a hairline gap that often gets ignored but is a direct path for water into the shell.
• Masonry gaps — between coping stones, between deck pavers and walls, or anywhere settlement has opened a seam.
• Crack repair — true structural cracks get rout-and-seal treatment with epoxy or urethane based on movement classification.

What we use

The mastic we install is a single-component, self-leveling polyurethane formulated for masonry expansion joints. It cures to a flexible, UV-resistant, chemical-resistant seal that moves with the joint instead of cracking out the second winter. We stock it in several colors to match the existing coping and deck — gray, tan, charcoal, beige — so the seal disappears into the joint visually.

Why our climate makes this critical

Mid-Atlantic pools see annual temperature swings of 80-100 degrees. Concrete deck and stone coping move at different rates with that swing. Without a working expansion joint, you get bond-beam cracking, coping push-up, and deck heave — all of which are dramatically more expensive to fix than re-sealing the joint every 5-7 years.

Frequently Asked Questions

How often should expansion joints be re-sealed?

Polyurethane mastic in our climate gets 5-10 years before it needs replacement. Older latex sealants often fail in 2-3 years.

How can I tell if my joint has failed?

Look for cracking, separation from the coping or deck, sponginess, missing chunks, or any visible gap you can fit a credit card into. If water is pooling against the coping after a rain instead of running off, the joint is gone.

Do you have to drain the pool?

No. Joint and crack sealing is done with the pool full.

How long does the work take?

Most residential pools take one full day for joint sealing and crack repair. Cure time before swimming is 24-48 hours depending on temperature.

Can sealing prevent a leak I already have?

Sometimes. If the leak path runs through a failed expansion joint, sealing fixes it. If the leak is in plumbing or in the shell itself, sealing the joint will not stop it — we pressure-test before quoting so you know which problem you actually have.