Flaking on bathroom ceiling

[Gwynston]

We have noticed in the past a small damp patch on our bathroom ceiling adjacent to the outside wall. It never got very big, so I wasn't sure if it was active or not, or caused by steam.

After a while mildew formed on it, so I treated that quite vigorously with a suitable cleaner (it took more than one attempt to kill the mildew). Having done that the ceiling paint dried and later started flaking. So I sanded the patch down to the plasterboard and covered it with BIN primer with the intention of then repainting.

Well, a few weeks passed without me ever getting around to painting and now the primer seems to be flaking off. The area doesn't look or feel damp, but I'm wondering what would cause the primer to flake and whether we have a problem?

 

[JohnD]

What leaks did you find when you looked in the loft above?

How long do you run the extractor fan during and after every bath and shower?

 

[Gwynston]

I haven't specifically looked in the loft for any leaks. As I said - there doesn't seem to have been any dampness since the original patch formed. Which is the basis of my question as I'm not sure what would cause the primer to come away if it there doesn't seem to be any dampness.

We don't actually have an extractor fan!
We tend to open the window for a while after the bath or shower has been used.

 

[JohnD]

I haven't specifically looked in the loft for any leaks.

I think you should.

The other very common cause of damp in bathrooms is condensation resulting from inadequate ventilation.

Damp is not a problem to be cured with paint.