PEBBLECRETE / MATERIAL LIBRARY
Why pool tiles come loose in hot climates, and how to choose between repair and replacement
Pool tiles usually come loose because of ageing grout and bedding, heat and moisture movement, poor original fixing, aggressive water or a moving shell, so establish the cause before choosing a repair or a new finish.
Pool tiles rarely come loose because the tile has worn out. Usually the adhesive or render behind them, or the grout between them, has stopped holding, and in hot climates heat, movement, unsuitable water chemistry and heavy use can make this happen sooner. Have the cause professionally diagnosed and any leaks ruled out before you choose between local repair, re-tiling and a new finish.
Why tiles come loose
Ageing grout and bedding
On most tiled pools, the joints and bedding age before the tile does. Cement-based grout gradually wears in circulating water. Grout deterioration and loss of bond behind the tile can develop together until tiles sound hollow and lift. For that reason, assess the whole immersed system, not just the joints you can see.
Thermal and moisture movement
Tile, adhesive, render and concrete expand and contract at different rates. In the tropics and the Gulf, the exposed waterline band, and the walls of an empty pool, can get very hot and then cool quickly in rain or when the pool is topped up. Refilling an empty pool with cooler water adds a further thermal shock to the old tiling. Without enough movement joints, stress builds up in the weakest layer.
Poor original bedding
Tiles fixed with spots of adhesive rather than a full bed leave voids that can fill with water. Other shortcomings can show up years later:
- adhesive or grout not suited to permanent immersion
- tiling onto render that had not finished shrinking
- filling the pool before the bedding had cured
Water chemistry
Water that is aggressive to cement-based materials can soften grout and expose the bedding. When investigating this, assess calcium hardness, pH and alkalinity together rather than treating each as a separate cause. In Southeast Asia, filling water from wells, rivers or lakes can be acidic. Trichlor (stabilised chlorine) tablets can lower pH further and add cyanuric acid, so record the treatment product as well as the readings. The same water can also affect the cement matrix of an exposed-aggregate finish, so do not assume a new surface is immune to it.
Movement in the shell
Settlement, ground movement, cracked concrete or a structural leak can move or wet the shell behind the tiles. Tiles that crack or lift in a line may sit over a crack. Unresolved substrate movement can cause failure, and the designer must specify appropriate repairs or movement details.
Diagnose before you decide
Carry out a sounding survey
Get advice from a structural engineer or an experienced pool contractor before you drain the pool. High groundwater can put an empty shell at risk, and an empty pool is exposed to the same heat that may have caused the problem. The exposed waterline band can be sounded while the pool is full.
Once draining is safe, the surface is tapped in a regular pattern with a light hammer or sounding tool. Hollow spots are marked on a plan of the walls, floor, steps and waterline. Visible loose tiles may come with hidden loss of bond elsewhere, so have its extent established professionally.
Read the pattern
Where tiles fail can suggest where to look:
- Along the waterline: heat movement or repeated wetting and drying.
- In a line or around a crack: movement in the shell.
- Around lights, inlets and fittings: leaks or poor detailing at penetrations.
- Across much of the pool: water chemistry or poor original bedding.
These patterns narrow the investigation. They do not prove a cause on their own. On a tile that has come off, check where the adhesive ended up: on the tile, on the wall, or pulled away with render attached. This shows which layer failed. Also review water-test records, treatments, any periods when the pool was drained and recent building work. Read the records in date order, because a single reading rarely explains a failure.
Check for leaks
Measure water loss over a period when the pool is not in use, and allow for evaporation. A bucket test is a simple place to start. If the loss cannot be explained, have a specialist investigate the structure, pipework, joints and fittings. Never treat a new finish as the fix for a leak you have not explained.
Your options
1. Local repair
Local repair may be suitable once assessment has confirmed the cause, the extent of the hollow areas and the condition of the surrounding layers. Ask for a professionally assessed repair scope using materials suited to immersion. Agree what the repair will look like beforehand: it may stay visible, especially if matching tiles are no longer available or the surrounding grout has aged.
2. Re-tile
If tiles have come loose across much of the pool, stripping and re-tiling may be the realistic answer. Ask for a coordinated specification for a permanently immersed pool, with a named contractor responsible for compliance. Unresolved causes can affect the replacement finish.
3. Change to a continuous exposed-aggregate finish
Some owners use the renovation to switch to a cement-based exposed-aggregate finish, such as PebbleCrete Classic, PebbleCrete Supreme or PebbleCrete Glass. It forms one continuous layer, nominally 10 mm thick, with no grid of grout joints. Movement joints are still included where the design needs them. A different finish has different maintenance requirements, but tile and exposed aggregate both depend on sound construction and good water care.
PebbleCrete supplies the material and technical support. Application is carried out by independent professional applicators. Unless agreed otherwise in writing, the finished result is the responsibility of the owner and their applicator.
Preparation still matters. Loose and hollow layers must be removed, and old tile that is still attached in places is not automatically a suitable base. Before finishing, agree who is responsible for substrate acceptance, waterproofing and preparation, in line with the current Method Statement and Substrate Acceptance Protocol. For more, see the “New pools and renovations” section of our application techniques page.
Plan for these points:
- Clearances: allow for the extra thickness at lights, drains, grilles, steps and coping.
- Waterline: a band of pool-suitable tile above the aggregate creates a separate zone that can be maintained on its own. Specify the tile, adhesive, grout and joints as one immersed-pool detail set to the operating water level, and agree how it will be cleaned.
- Colour: choose from a physical sample viewed wet. The owner approves the applicator’s on-site panel and agrees the appearance criteria. Natural stone and glass vary between batches, so the finished surface is judged against the approved panel and sample, not against photographs.
- Start-up: once the applicator gives written release, fill the pool promptly and without interruption with clean, tested water. Then follow the approved start-up instructions for brushing and testing.
The finish is decorative. It is not structural repair or waterproofing, and each of those needs its own scope of work.
Get the scope right
A quotation for the finish and a quotation for the renovation cover different work. Ask for the preparation work in writing, with a named person or firm responsible for each item:
- removing loose and hollow layers
- structural and crack repairs
- waterproofing and water testing
- render and levelling
- fittings, lighting and equipment changes
- the finish itself, filling and start-up
Whichever option you choose, keep the water balanced afterwards. Our water treatment guidance lists the readings to record and explains what they mean.
In Thailand: Pebble Pools (pebblepools.co.th) offers tile repair and regrouting and pool inspection with a written report. Their local guide: pool tiles coming loose in Phuket.
Frequently asked questions
Can an exposed-aggregate finish go straight over existing tiles?
Not straight over. If tiles are coming loose in a pool, any tile you keep needs careful assessment for that project, because the finish is only as secure as the layers beneath it. Whether tile can stay, and how it is prepared, should be agreed under the current Method Statement and Substrate Acceptance Protocol.
Will changing the finish stop the problem coming back?
Not on its own. If the cause was shell movement, a leak or aggressive water, fix that first. A new finish brings different maintenance requirements, but it still needs sound construction and good water care. As a planning figure, an exposed-aggregate pool finish is generally expected to serve for 15–20 years. This is an industry estimate, not a warranty term. Where an individual pool falls within or outside that range depends on substrate preparation, application quality, water chemistry and routine maintenance.
Will a new finish fix a leaking pool?
No. Find and repair the source in the structure, pipework, joints or fittings. Then complete the specified waterproofing and water test, and record that it has been accepted before the new finish goes on.
Photographs and screen colours are illustrations. Confirm colour and texture with a current physical sample viewed wet and an approved on-site mock-up.