Ceiling – How to clean mold off the bathroom ceiling

First find out whether it is mold or not. What you do next depends on this.

Assuming it is mold you need to do two things.

1. Clean it off - disinfectant/bleach solution should do the job.

2. Find out why it's forming. This is the important bit as if you just do the first step it will come back.

The usual cause is condensation which in a bathroom means you have insufficient ventilation.

So the ultimate cure is to fit an extractor fan above the bath to remove the steam. You can get ones that wire up to the light circuit and then "run on" after the light is switched off to provide additional ventilation.

Once you've done this redecorate.

My guess is that the mould has grown into the grout; live or not, the bio-gunk they have produced has stained the grout.

A complete re-tiling should not be necessary; you should be able to simply remove the old stained grout between tiles and re-grout. You can remove and replace the stained/mouldy caulking as well. There are attachments for almost any rotary/oscillating/reciprocating tool to dig out grout, and there are also hand tools available for delicate areas. Simply work back down to either the depth of the tile or until the staining is gone, apply one last coat of bleach solution or Tilex, let try completely, and then sponge in a new layer of grout, making sure to get it into all the crevices as deeply as possible. To prevent mould growth in the future, you can apply a grout sealant; this will absorb into the grout and cure into a waterproof layer that will prevent the mould from "digging in" like it did.

If you are sure the mould is dead, there are also "grout restoration" kits that will cover the stain, and some of these products will seal the grout, preventing water permeation and thus avoiding mould in the first place. These are generally cheaper and easier than a re-grouting. But, if the mold's not completely dead, and the grout isn't completely dry, the mould can come back under a layer like this and remain visible, or even cause the repair to crack and flake off.