Wall / ceiling dry after water damage?

andre_xs

Dear All,
we had two independent water damages in the upstairs bathroom. One was a bigger 'flood' (burst pipe for a couple of minutes), and the other one was a bathtub silicone seal which wasn't sealing anymore (so more of a dripping thing). The water damaged the ceiling and wall in the kitchen (which is underneath the bathroom). Probably the dripping from the broken seal went on so that you could also see some dampness on the other side of the downstairs wall (living room).

The house is built in the mid 1950s, and the ceiling is standard wood beams/rafters (kitchen ceiling plasterboard). The walls are plastered brick walls. In the kitchen, it was so wet that the plaster bloomed up quite a bit.

Both types of water ingress have been stopped in last December, so at least 6 months ago. The floor in the bathroom allows a bit of ventilation for the space between kitchen ceiling and bathroom floor (we lifted part of the floor, so that there are only the floorboards, which have gaps). It hasn't been repaired/touched since then, but we'd like to get it repaired now.

1) Is it save to assume that the walls and ceiling are dry now?
2) Should we check for anything, e.g. mould?
3) If we should check, how best to do this? upstairs, the bathtub sits on the damaged part (= difficult to lift the floorboards). We could cut out a bit of the plasterboard ceiling downstairs?
4) Should we replace the plasterboard, or is just painting it fine?

Any tips and experiences would be greatly appreciated

Best wishes,

Andre

Bendy_House

1) Yes, if there's been no more water, it should be bone dry.

2) There shouldn't be mould, as it should have dried out, and any mould that 'may' have formed should have died away. The 'slow' leak is the most concerning of these, as long-term damp can cause wet and/or dry rot, but this usually requires MANY months of dampness, and - again - once it's fully dry, it should stop. I think... The 'slow' leak, how long do you think that went on for?

3) If the ceiling plasterboard is still flat with no sagging, then it should be fine to just repaint. Any stains on it? If so, you'll likely need a stain blocker first.

The kitchen wall plaster - what does 'bloomed up' mean? Has it actually swollen? Does it sound different when tapped to an unaffected area?

andre_xs

Thanks for the reply.

2) I'm not sure how long it went on for, maybe 3-5 months or so?

"bloomed up": I just had a look again. When tapping, it all sounds the same. It may actually not have swollen, not sure. The paint is flaking (which may leave the impression), and it may have been somewhat uneven already before without us really noticing. That part has been chased up before to lay the cable for a further outlet and may have been just poorly plastered before.

Bendy_House

Continuous dampness in timber over 3 to 5 months could start the germination of rot spores. That's pretty much all that should/could have happened, tho' - germination has begun. However, once 'dry', the growth stops. I cannot see any way that any actual damage has been caused in that short period of time.

I would personally not be concerned about any continuing rot in your circumstance, and certainly wouldn't bother taking down a ceiling/lifting a floor (unless it's easy to both do and replace) in order to check. If it was easy to do, tho', then I probably would, and might even spray the ex-damp area using Everbuild Lumberjack Triple-action preservative (a pleasant stuff to use, even indoors).

This has to be your call. For instance, if you are 100% certain that ALL the leaks have been stopped, and that there aren't any other potential sources of damp in that area, then I'd - personally - be happy with that. If, however, you cannot be certain, then I would like to lift a floorboard and use an endoscope camera (pretty cheap to buy and use with your phone) to check the area. Once a f'board is up, it should also be pretty easy to lance-spray (cheap garden sprayer) Lumberjack over that area, tobesure tobesure.

Again, if this is a modern build - cavity walls, good insulation - I wouldn't worry. If, instead, you have a single-skinned Victorian property, and this affected area was against an exterior wall, then I'm pretty sure I would investigate - and spray. It takes a lot to begin to germinate dry rot, and it dies away when the % moisture drops to below, ooh, 20%. But, once it has started, if the dampness doesn't fall to the level you'd expect in a house construction - say it hovers around 25% or a bit more due to a tiny amount of penetrating damp from the walls, an amount that in itself wouldn't START germination on its own - it could now continue. 

Modern house, 5 months damp, 5 months to dry, and no more leaks = not to worry (imo).