Introduction
Noticed a hairline crack or a deeper fracture forming along your pool wall? Don’t panic—fixing a cracked pool wall is possible with the right materials, a little time, and a careful approach. In this complete step-by-step guide, you’ll learn how to assess, repair, and prevent cracks in concrete, gunite, or plaster pool walls, restoring both strength and appearance.
Why Fixing Pool Wall Cracks Matters
Cracks in a pool wall can start small but turn into big problems if left unaddressed. Even hairline fractures allow water to seep behind the wall, weakening the structure and potentially causing:
- Leaks and water loss
- Algae growth inside the crack
- Further expansion due to freeze-thaw cycles
- Damage to the pool’s rebar or shell
- Aesthetic issues that ruin your pool’s appearance
Timely repair helps maintain the integrity, safety, and value of your swimming pool.
Step-by-Step Guide to Fixing a Cracked Pool Wall
Step 1: Identify the Type of Crack
Before you fix anything, determine the type and severity of the crack:
- Hairline cracks: Small surface cracks often caused by shrinkage. Mostly cosmetic.
- Structural cracks: Wide, deep, or diagonal cracks that may run through the shell. These are more serious.
- Spider cracks: Multiple small cracks fanning out in a pattern—usually surface-level.
- Leaking cracks: Any crack that actively loses water is a priority repair.
Pool Owner Tip: Mark the ends of the crack with a waterproof marker and monitor over a few days to see if it spreads or leaks.
Step 2: Gather Your Tools and Materials
What you need will depend on the type of pool (concrete, plaster, or fiberglass). For concrete or plaster pools, gather:
- Safety gloves and goggles
- Wire brush or grinder
- Chisel and hammer
- Pool putty, hydraulic cement, or crack filler
- Trowel or putty knife
- Waterproof epoxy (for structural cracks)
- Paintbrush or sponge (for cleaning)
- Pool patch plaster (optional)
Caution: If you have a fiberglass pool, crack repair usually requires a gel coat patch and may be better handled by a professional.
Step 3: Drain or Lower the Pool Water (If Needed)
If the crack is above the waterline, you can fix it without draining. If it’s below the waterline or leaking, you’ll need to lower the water level at least 6 inches below the crack to expose the repair area.
Safety Tip: Don’t drain the entire pool unless absolutely necessary—especially for fiberglass or vinyl liner pools, which can shift or collapse without water weight.
Step 4: Clean and Prepare the Crack
Use a wire brush or angle grinder to clean out the crack and remove loose debris. For deeper or structural cracks:
- Use a chisel and hammer to open the crack into a “V” shape, about 1/2 inch deep and wide. This helps filler bond better.
Wipe or rinse the crack to remove dust, dirt, or algae. Let it dry completely before applying patch material.
Step 5: Apply Crack Filler or Hydraulic Cement
Depending on the crack size and location:
For Hairline or Small Cracks:
- Use pool putty or a vinyl concrete patch.
- Knead or mix the compound per instructions.
- Press it firmly into the crack using a putty knife.
- Smooth the surface and let it cure for 24 hours.
For Deeper or Leaking Cracks:
- Mix hydraulic cement quickly—it sets fast.
- Push it deep into the crack using gloved fingers or a trowel.
- Apply firm pressure until the crack is fully sealed.
- Hold in place for a few minutes, then smooth the surface.
Pool Owner Tip: Hydraulic cement expands slightly as it sets—great for sealing leaks under pressure.
Step 6: Apply Waterproof Epoxy (If Needed)
For structural cracks or large cracks below the waterline, an epoxy injection kit or pool-grade waterproof epoxy is a long-lasting solution.
- Follow the kit’s instructions to mix and inject epoxy into the crack.
- Use a cartridge gun for deep crack filling.
- Smooth the outer surface with a putty knife.
- Allow to cure as directed (usually 24–48 hours).
Step 7: Finish With a Pool Plaster Patch (Optional)
If your pool has a plaster surface and the repair area is visible:
- Mix pool plaster patch according to manufacturer’s instructions.
- Apply over the repaired crack to blend with the existing surface.
- Smooth with a trowel and let cure before refilling.
This step improves aesthetics and adds a protective seal over the repair.
Step 8: Refill and Monitor the Pool
Once your repair has cured completely, refill the pool to normal water level and turn the pump system back on.
Keep an eye on:
- Water levels (watch for signs of leaks)
- The repaired area (check for discoloration or re-cracking)
- Filter pressure (in case of debris or leftover cement particles)
Common Mistakes to Avoid
- Ignoring Structural Cracks: Cosmetic repairs won’t fix a deep crack—get a professional assessment.
- Skipping Surface Prep: Filling a dirty or loose crack will result in early failure.
- Using Household Sealants: Only use pool-grade materials made to withstand water and pressure.
- Filling a Wet Crack With Cement: Most patching compounds require a dry surface unless labeled as underwater-use.
- Overlooking Rebar Damage: Exposed rusting rebar should be removed or professionally treated.
Extra Tips & Pool Hacks
- Mark Your Pool Walls Annually: Use waterproof markers to track changes in small cracks.
- Underwater Repair Products Exist: If you can’t drain the pool, underwater epoxies or two-part putties can be applied directly.
- Use a Leak Detection Dye: Add colored dye near a suspected crack to see if water is being pulled into it.
- Consider Waterproof Sealants for Preventive Use: After repairs, apply a pool-safe sealant to vulnerable areas like steps or corners.
For major issues or deep structural cracks, consult a licensed pool contractor for permanent solutions.
Conclusion
Fixing a cracked pool wall might seem intimidating, but with the right tools and step-by-step process, you can handle most minor to moderate cracks yourself. Regular inspection and prompt repair will prevent leaks, extend your pool’s lifespan, and keep your swimming area looking its best.
✅ Bookmark this guide for your next pool inspection or maintenance day!