Water damage under bath

[ragingwood]

Purchased a house a few months ago and had an artex ceiling skimmed over which had a small area with water damage from the bath above.

Figured it was historic damage from years gone by as the bath seal looks ok.

Allowed the plaster to fully dry and gave it a mist coat yesterday but today there are yellow spots near the repaired area. I figure some undercoat or stain blocker will fix that.

But I'm wondering why is it staining? The bath/shower hasn't been used in at least 2 months as we don't live there yet and the seal around it looks alright.

Had a look under the bath and things don't look good. I forgot to feel any of it, so I don't know if its actually still damp but there's plenty of damage.

Photos (see captions): https://imgur.com/a/xi03B

I hadn't planned on renovating the bathroom yet, but should I move the bath and get all that rot removed now? First time ever dealing with this.

Thanks.

 

[endecotp]

A drip from the pipe supplying the taps would continue to drip even when the bath's not being used.
But you need to get in there and feel around and discover where the water is actually coming from. Certainly the marks on the wall look like a leaking seal (is there a shower above the bath?) but there could be multiple problems.
You don't need to rush, unless you think the joists might be rotten - which I think is unlikely.

 

[Doggit]

Who renovated the bathroom and did the tiling. Did the previous owner renovate it because there were issues, and did a tart job rather than a proper refurb. The seeping damage to the walls may have been the reason for the upgrade (assuming they did it) but the ceiling getting stained again after being skimmed, suggests there's still wet plaster above it.

If there is rot, then you'll definitely need to get rid of it, but you don't want to do to much damage in the bathroom unnnecessarily. Feel everywhere underneath the bath to check if anythings damp or leaking. And use a screwdriver to dig into any wood that's questionable, and see if it's weak or rotten. If you can, leave the bath in place, and remove what boards you can to get at the area underneath, and once you've ascertained the extent of any damage, then you'll start stripping the bath out.