Grout Failure

tile grout failure

If you have mouldy grout then it could be an indication that you have grout failure.

Put simply, grout should not turn mouldy.

Why? Because mould needs moisture to survive and if your grout is retaining moisture it is not waterproof.

There could be several reasons for this:

  • wrong grout used
  • bad application
  • cracked grout

Wrong Grout Used

Not all grout is waterproof. It should be but that is not always the case.

There are many different formulations of grout and some of these are not suitable for use in wet areas. If you have this type of grout in your shower or above your bath then you will soon know about it.

The grout will start discolour and eventually it will turn black with mould. This is very unsightly and also not great for ones health.

The only solution to this problem is to rake it out and start again. It is a bit of an onerous task but is is relatively straightforward.


Bad Application Of Grout

The application of grout is not an exact science.

It is applied with a grout spreader to force the grout into the joints between the tiles. It is possible to leave small gaps here and there which can lead to water ingress.

The second pat of the application process involves sponging off excess grout. This is another process that can lead to problems because if too much grout is removed gaps and pin-holes can appear. Water will get through these gaps and start to cause problems.



Cracked Grout

Most grout is extremely brittle and will not tolerate any movement. There are several sources of movement that can cause grout to crack.

The most common area where this happens is above a bath. When the bath is in use it can flex slightly, putting pressure on the tiles and grout. Baths with excessive movement can also crack the tiles as well as the grout.

Shower trays can suffer from the same scenario. And obviously this is a serious issue inside an enclosure as there is always going to be a lot of water running down the walls.

You can try to re-grout the tiles but in this situation the problem is likely to re-occur if the movement is not eliminated. See this article for details on preventing a bath from moving



What Is The Best Solution?

That will depend on exactly what has caused the problem in the first place (this article will help you find out).


There is a solution that will always work, will always eradicate the problem and will be permanent:

Install waterproof wall panels straight over the problem area. Quick, clean and cheap. It is an easy job to undertake and the results are amazing:


bathroom grout before


bathroom wall panels after







remember that these are not tiles, so there is no grout, no mould and no maintenance

look at some of the amazing panel designs available

vicenza grey bathroom wall panels

cover tiles with panels

Filo tle effect bathroom wall panels

vicenza blue marble

You Need To Take Grout Failure Seriously

Grout failure is not just a cosmetic issue. It can lead to serious structural damage if left to get worse.

Small amounts of water leaking through your tiles can cause wood to rot. So floorboard, wall studs and even joists can rot through causing major problems for the integrity of the property.

Once water gets through some materials can act like a sponge, drawing more and more moisture through the failed grout. Plasterboard is a product that displays these qualities. They never dry out,  so the house can start to smell musty due to the permanently damp conditions.

Seals around the bath and shower tray are also a vital tool in preventing water escaping the bath or shower area. So make sure these are in good condition too. There is more info on this here.