A bubble or blister in a shower panel is seldom just a cosmetic complaint – something is coming unstuck beneath it. The adhesive has failed, moisture has found its way in, or the panel is being pushed outwards from the other side. The sooner an investigation can be made as to which, the sooner an unsightly hole in a wall can be avoided.
This article covers the most common causes of a bubbly panel, how to identify their effect, what can and cannot be repaired, and how to avoid them when re-fitting a panel.
What Bubbling Looks Like
Bubbling is not always dramatic – it can appear as a rise in the surface that is only noticeable in direct light or a soft indention that yields to pressure. The bubble or blister will usually spread over time, and the surface might peel at the edges or feel spongy to the touch.
Pay attention to the location of the bubble. Bubbles at the base, along the tray or at a joint point suggest moisture has got in from there, and bubbles in larger panels away from a joint point suggest a problem with adhesion or the substrate. Bubbles near a radiator or heated towel rail could be heat related. Noticing any pattern can speed up diagnosis before a panel is removed.
The Most Common Causes
One of the most common reasons is water getting in behind the panel and pushing it away. This can occur if a sealant has split, a joint is not water tight or a hole has not been sealed. Water can remain trapped there, weakening the adhesive and swelling any core or board behind the panel, pushing it outwards.
This can be exacerbated if the panel is fixed to the edge of a tray – a small amount of water behind the panel along a joint is enough to cause an issue.
Panels that have been fixed to a dirty or damp wall will not stick to it well. Painted, peeling, flaky or damp walls, new plaster that has not dried out, tiled surface with residue and more are all possible causes. The adhesive may appear to be fine when the panel is placed on the surface, but it may fail weeks or months later, causing a gap to appear.
Using the wrong adhesive or too little of the correct product has a similar effect. Some systems require full coverage of adhesive, others use a bead, and either type failing results in unsupported areas.
Moisture in a wall can push into the adhesive and push the panel up. This can occur when there is penetrating or rising damp, new plaster that has not been allowed to dry and with walls that have otherwise been affected by water. In solid walled older properties, the moisture in a wall can be extensive and sealing in behind a panel can change how a wall dries.
Heat can cause some panel materials to distort, and adhesives to weaken. Radiators, heated towel rails and underfloor heating pipes are obvious sources, but a lack of ventilation or sunlight on a hot day can have a similar effect. Manufacturers usually state a temperature limit, so check the advice with your panel and adhesive.
Uneven walls or panels that have been fitted to bowed or uneven walls can have pockets of trapped air that expand as the room warms up. Some products are flexible and will conform to the wall, but some are rigid and the expansion can cause a bubble to appear.
Some panels are fitted to a backing board, or have an absorbent core that swells when exposed to moisture. When exposed to water, the panel expands and the structural integrity is lost, resulting in a bubble. This is more common with cheaper boards, or where a panel has been cut, leaving the edges exposed.
Changes in the structure of timbers or adhesives can cause a panel to lift and bubble, especially in conjunction with moisture. The movement can be increased in hotter weather. Panels that have been in place for a long time and bubble in multiple places may simply be reaching the end of their life.
How to Identify What You Are Dealing With
A few simple checks can narrow down the cause before any investigation.
Press the bubble – a firm, hollow feel suggests an air or adhesive gap, while a soft, spongy bubble suggests moisture and a possible weakening of the panel's structure.
Check the sealant – look along the joints near the bubble for any gaps, splits or discolouration.
Look for a pattern – several bubbles low on a wall suggest moisture at the base, while a single bubble in a larger panel suggests an adhesion issue.
Look at the room – is there a radiator or heated towel rail, or is the wall external?
Check for a leak – if there is a stain, mould or smell, treat it as a moisture problem first.
If you are unsure, a plumber or damp specialist can use a moisture meter or thermal camera to identify the cause without having to remove the panel.
Can a Bubbling Panel Be Repaired?
It depends on the cause and the extent of the issue, but in some cases, a panel can be repaired. A simple summary is: if it is a localised adhesion fault in a dry wall, it can be repaired by removing the affected panel and reapplying. If there is any moisture involved, the source must be resolved before the panel can be reattached – in most cases, it will have to come away.
Small, firm bubbles in dry areas can sometimes be repaired by injecting a suitable adhesive using a fine nozzle tool, pressing the surface flat and holding in place with tape or weight until cured. Use a recommended product to avoid staining, and take care when repairing to avoid marks. It is important to remember that the repair is unlikely to hold well, especially against a large failure.
If a section of the edge has lifted, it can sometimes be cleaned out, the area dried, and the edge reattched and resealed. Ensure that the wall is dry before refitting and that the cause of the failure has been dealt with.
Soft, swollen or water damaged panels rarely repair well – the internal structure of the panel has been compromised, and they should be replaced. The wall should be dry before refitting.
Panels that have been distorted by heat rarely recover, and should be replaced. Ensure that the product is suitable for the room or, if replacing sources of heat, address this first.
How to Ensure the Cause Has Been Addressed
A bubble is a symptom, and not addressing the cause means it is likely to return. Replace any failed sealant, address a leak and dry out a damp wall before attempting any repairs. Use a moisture meter where possible, as surfaces may feel dry even if there is moisture beneath the surface.
If you are looking to replace damaged sections or an entire enclosure, it is worth comparing options – a range of shower panels made for wet room use generally include a range of trim options and fitting advice, which reduces the risk of repeating the same fault. It is rare for older panels to match a new panel, so if the whole length of an enclosure is affected, it may be worth considering a replacement.
How to Avoid Bubbling When Fitting New Panels
The majority of bubbling can be avoided during installation.
- Fit panels to a clean, dry, sound and flat surface, repairing any damaged plaster.
- Use the correct adhesive in the pattern and quantities stated by the manufacturer.
- Ensure that panels are fitted to a stable backing where the wall is uneven, using battens or a backing board.
- Seal cut edges and holes, as these are the weakest points.
- Ensure that joints, trims and joints with the tray or bath are sealed correctly.
- Allow the adhesive and sealant to cure before using the shower.
- Ensure that panels and adhesives are rated to handle any heat nearby.
If you are considering finishes at the same time, textured or patterned panels tend to conceal imperfections better than high gloss colours, and this overview of Wall Panel Trends shows the range of finishes currently available.
Ventilation and Everyday Care
A damp bathroom will shorten the life of its panels. Ensure that an extractor fan is used during and after showers, and wipe or squeegee the surface dry. Maintain a warm enough room for steam to not condense on cold walls. Check the sealant every few months and replace any that has split. A well maintained, calm Spa-Style Bathroom depends on these routine care activities as much as the initial installation.
When to Call a Professional
Some issues are best dealt with by someone with the right tools and experience. These include panels that continue to bubble, a visible mould or smell or large areas of soft panel, a stain on a ceiling or wall, or if the source of the moisture cannot be found. A plumber can trace and cut off leaks, and a specialist can assess the wall. If the fault is with a recent installation, speak to the installer or supplier as the terms for a warranty or guarantee often depend on the product and the circumstances.
A Practical Next Step
Press the bubble and check the sealant around the area – what lies behind the wall? A firm bubble in a dry area might be a simple repair, but a soft one, or bubbling with staining or a smell, should be treated as a moisture problem. Stop using the shower if you suspect a leak, find the source and let the wall dry out before repairing or replacing the panel.
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