What plaster damage can you patch yourself?
Pool plaster is a thin cement-based finish over the pool shell. Small, localized damage is often reasonable for a careful homeowner to repair:
- Chips and small pits.
- Short hairline cracks in the plaster layer only.
- Rough spots in a small area.
Larger problems usually call for a professional:
- Widespread roughness, staining or flaking across the pool.
- Many hollow-sounding areas.
- Cracks that leak, widen or run across large parts of the pool (see how to fix a crack in a pool).
Check for hollow spots and leaks first
Tap the damaged area and the plaster around it gently with the handle of a screwdriver. A dull or hollow sound can mean the plaster has separated from the shell below. A patch applied over loose plaster tends to fail. If a larger area sounds hollow, plan to remove it or get a professional opinion.
Also confirm the damage is not part of a leak. If the pool is losing water, find the source first; our article on an inground pool leaking in winter has simple ways to confirm water loss.
Tools and materials
- A pool plaster patch kit or cement-based repair product made for pools. Read the label to confirm it suits your surface. Some products are not intended for painted or fiberglass surfaces.
- Chisel and hammer, or a small carbide scraper.
- Wire brush and sponge.
- Mixing container and stir stick.
- Trowel or putty knife.
- Safety glasses, gloves, and a dust mask.
Safety before you start
- Chipping cement creates dust and flying fragments, so wear eye protection and a dust mask.
- Cement-based products are alkaline and can irritate skin and eyes. Wear gloves and rinse splashes with water.
- Lower the water only as much as needed, usually a few inches below the damage. Do not fully drain a pool without advice from a pool professional, since a drained shell can be damaged by groundwater pressure.
- Be careful with ladders, wet surfaces and any electrical equipment near water. Turn off pool pumps and lights while you work.
Step-by-step: patching a chip or small crack
- Lower the water. Bring it a few inches below the damaged spot. Turn off the pump.
- Remove loose material. Chip away loose or cracked plaster until you reach solid material. Many kit instructions ask for a recess of about a quarter inch, so the patch has something to grip.
- Clean the area. Brush out dust and debris, then wipe with a damp sponge. Follow your kit’s instructions on whether the surface should be dry or damp when you apply the patch.
- Mix the patch. Follow the product ratios exactly. Many kits combine a dry mix with water or a liquid bonder. The target is usually a thick putty that stays put on a trowel.
- Press it in. Work the patch firmly into the damaged spot with a trowel or putty knife so it fills the gaps. Leave it slightly proud.
- Smooth it. Use a damp sponge or trowel to finish flush with the surrounding surface. Do not overwork it.
- Cure. Follow the cure time on the product label before refilling or exposing it to chemicals.
For color, patches often do not match old plaster exactly, and colored products are sold in a limited range. A slight mismatch is common.
Can you repair pool plaster underwater?
Some fast-setting or underwater patching products exist, and they are sometimes used for small repairs when draining is not practical. In general, results tend to be better when the area is above the waterline and can be prepared and cured properly. Treat underwater patches as a short-term measure unless the manufacturer states otherwise.
Can you plaster over old plaster?
Sometimes. Resurfacing coats designed to bond to sound existing plaster are sold for do-it-yourself and professional use. The old surface must be sound, clean and prepared as the product directs. If the old plaster is hollow, flaking or heavily cracked, the new layer is unlikely to hold. Some products are not suitable for painted surfaces, so check labels. For full resurfacing, many owners hire a pool plaster contractor.
How much does it cost to replaster a pool?
Costs depend heavily on pool size, finish type, region and the amount of prep needed. A pool of around 10,000 gallons is a smaller pool, but there is no reliable single number: quotes vary by contractor and by whether the old plaster must be removed. Ask for at least two written quotes that show what is included, such as demolition, finish type, water start-up and chemical balancing.
Curing and refilling
Fresh cement needs time to harden. Keep the patched area undisturbed and follow the manufacturer’s cure time before it contacts pool water. After refilling, keep the water balanced according to your plaster or product guidance, since poor water chemistry can damage new plaster.
When to call a professional
Consider a pool plaster or repair professional if:
- Large areas are hollow, flaking or rough.
- Cracks leak or keep returning after patching.
- You see signs of structural movement.
- You need to drain the pool.
- The pool has a fiberglass or painted finish where cement patches are not suitable.