Tile and mosaic repair

When you need it

• Tiles have come away or sound hollow when tapped.
• Grout is cracked, washed out or missing.
• Cracks run along the waterline band or between the coping and the pool edge.
• Sharp edges or missing mosaic pieces create a cut risk.
• Tiles are lifting after a leak, a pipe repair or a long period with the pool empty.

How a specialist does it

Repair starts with finding out why the tiles failed. ARDEX describes the waterline as a severe environment of wet and dry cycling, rapid temperature changes and moving water. The pool shell and the surrounding deck are different materials that move differently, so anything bonded rigidly across that joint is very likely to crack.

A typical repair:

1. Survey. Tap testing maps hollow areas, cracks are checked, and the specialist judges whether the problem is local or follows a joint.
2. Remove loose tiles and failed grout back to sound material, and clean the bed.
3. Prepare the substrate. UltraTileFix guidance calls for removal of any laitance and release agents, with power washing often enough, and priming of absorbent surfaces.
4. Re-bed. Tiles are fixed with a highly modified cementitious adhesive capable of continual immersion. UltraTileFix stresses a full bed without voids and recommends a minimum bed depth of 3 mm.
5. Grout. UltraTileFix explains that standard grouts are water resistant, meaning they keep their strength under water, which does not mean they stop water passing. It suggests epoxy grout where a waterproof grout is needed, where aggressive cleaning chemicals are used, or where wave machines run.
6. Movement joints. UltraTileFix says movement joints should be planned before tiling, with sealant at least at wall and floor junctions. ARDEX recommends a movement joint at the boundary between the pool shell and the surrounding slab, or bonding the coping to the surround and sealing it to the pool rim with a flexible sealant.
7. Cure before refilling. Adhesive and grout makers state cure times before water goes back in. Ask for them in writing.

A small repair can sometimes be done by lowering the water rather than draining the pool. That depends on where the damage is and what the specialist recommends.

What to ask before you hire

• What do you think caused the failure, and will the repair deal with that cause?
• Which adhesive and grout will you use, and are they rated for permanent immersion?
• Will you add or renew movement joints at the coping and junctions?
• Can you match the existing tile or mosaic, or will a visible patch remain?
• Does the job need the pool drained, and how long before it can be refilled?
• Should the area be checked for a leak or waterproofing failure first?

UAE notes

Strong sun and large daily temperature swings put the coping and waterline under the most stress, so cracks often show there first. Mosaic from older pools can be hard to match, so ask whether spare tiles were left by the original builder.

Dubai Municipality's plan approval guidelines require pool floors to be light coloured with a smooth surface that withstands frequent cleaning. If you are retiling a larger area, check with the specialist that the new finish still meets that.

Shared and hotel pools usually need a closure while adhesive and grout cure. Check with building management on notice periods for residents and guests.