---
title: "What Is Expansion joint? Pool Glossary | Marina Pool Services"
description: "An expansion joint is a gap between the pool and the deck that lets each material move without cracking."
url: https://marinapool.multisites.ai/glossary/expansion-joint
publisher: Marina Pool Services
phone: +1-817-896-1120
quote: https://marinapool.multisites.ai/contact
---

Surfaces and decks

# Expansion joint

An expansion joint is a gap between the pool and the deck that lets each material move without cracking.

Concrete and stone grow and shrink with heat and soil moisture. The gap gives them room. A flexible sealant fills the gap to keep water out.

When the sealant dries out, shrinks, or peels, rain and splash water can seep under the deck. That can wash out soil and cause cracks. Check the joint each season. Hard, cracked, or missing sealant needs replacing. Marina Pool Services offers [Deck-O-Seal joint sealing](https://marinapool.multisites.ai/our-services/deck-o-seal).

[Marina can helpDeck-O-Seal & Joint Sealing](https://marinapool.multisites.ai/our-services/deck-o-seal)

## Related terms

-   [Pool mastic](https://marinapool.multisites.ai/glossary/pool-mastic)
-   [Deck-O-Seal](https://marinapool.multisites.ai/glossary/deck-o-seal)
-   [Coping](https://marinapool.multisites.ai/glossary/coping)

## Need a hand with your pool?

Call or text and tell us what your pool needs. Estimates are free for qualifying services, and same-day estimates are possible when the schedule allows.

[Call (817) 896-1120](tel:+1-817-896-1120)[Get a quote](https://marinapool.multisites.ai/contact)

![A pool technician working on an equipment pad](https://marinapool.multisites.ai/_astro/technician-equipment-pad.BW5xZMNY_Zum1K5.webp)