Drying out after a long slow leak

SteveRobert5a · Dec 10, 2018

Had a slow leak in a first floor bathroom toilet cistern, and it's probably been going for weeks. This is an ensuite that doesn't get used much, and the water was dripping from the service valve and running down the pipe into the cavity, close to an exterior wall. Parts of the chipboard floor panels in the bathroom have become damp, although it's hard to say how badly without taking up the floor covering (the next job). The ceiling on the ground floor directly below the leak was hidden from view by wall-mounted cupboards, so we didn't notice the problem until the coving started going black. Closer inspection revealed the dry wall plasterboard is damp along with a square meter's worth of ceiling and a couple of meters of coving.

With the leak now fixed, the question is about lasting damage. I'm assuming that ceiling and walls downstairs can be fixed up fairly easily once they've had a chance to dry out but not sure about the effect of water on chipboard floor panels. Any views on the likelihood of having to replace them (and basically rip out the bathroom fittings and start again). Never had a leak like this before and I know it's not really plumbing, but the professionals here must have seen plenty of leaks - any advice?

Murdoch · Dec 10, 2018

It all depends on how old the property is and how long it’s been wet for.

Use of a damp meter will help you gauge how it’s drying out .... and they don’t cost much

Ventilation and warmth are needed to speed up the drying process

WC1 · Dec 10, 2018

Impossible to tell until it's all dried out. Dehumidifier not expensive from hire shops. Also airflow as said above, do what you can to open things up and get air moving will also prevent it all going smelly... 😉

Chuck · Dec 10, 2018

SteveRobert5a said:
With the leak now fixed, the question is about lasting damage. I'm assuming that ceiling and walls downstairs can be fixed up fairly easily once they've had a chance to dry out but not sure about the effect of water on chipboard floor panels. Any views on the likelihood of having to replace them (and basically rip out the bathroom fittings and start again). Never had a leak like this before and I know it's not really plumbing, but the professionals here must have seen plenty of leaks - any advice?

In my opinion, chipboard only has one good property: it's cheap. From every other point of view, including water resistance, it's relatively useless.

Water gets sucked into it by capillary action very rapidly. Over a matter of days this causes the fibres to swell leaving the boards distorted, swollen and crumbly, even after drying out.

If you've seen what happens to a wheetabix when you leave it in milk for too long, you'll get the basic idea.

That said, some types of chipboard claim to be water resistant but they aren't often used in my experience and IIRC they are a greenish colour. Also 'water resistant' and 'mosisture resistant' are not the same thing as 'water-proof'.

If you want to be sure, take out a sample and leave it standing in some water for a few days and then dry it out.

Edit: I've just thought of a second good property: it's not MDF, which I dislike even more.

Rob Foster · Dec 11, 2018

If the water damage is not visible...it’s ok. If it does not smell it’s ok. If it’s not structural,it’s ok . Lob a load of bleach on it and things should be ok . Rob Foster aka centralheatking

SteveRobert5a · Dec 11, 2018

Thanks for all the input. Will have a go at drying things out and then see where we are. I'll try probing the floorboards with a moisture meter and screwdriver to assess if they've become sodden. There's no cavity wall insulation so I presume if the inner wall breeze blocks have got damp they'll just dry out over time with no ill effect?

Welder · Dec 11, 2018

SteveRobert5a said:
Thanks for all the input. Will have a go at drying things out and then see where we are. I'll try probing the floorboards with a moisture meter and screwdriver to assess if they've become sodden. There's no cavity wall insulation so I presume if the inner wall breeze blocks have got damp they'll just dry out over time with no ill effect?

Where do we start?

Once std chipboard is soaked it loses structral integrity. Replace it.
DO NOT (IMHO) use dehumidifiers to dry it out. It does it too quickly and you will see more damage as a consequence.
Mould is NOT good for your health. It needs removing.
This whole thing is an insurance claim. You need to check your terms & conditions BEFORE calling anyone. What you have hear is 'consequential damage'. All of this should be put right by insurers. Ask a local plumber in to assess damage and list all out that needs to be done to 'set you back to teh position you were in prior to the event'. Yes it will cost you but only your excess and everything should then be back to perfect.
DO NOT call insurers BEFORE working out they are liable. If you do and DO NOT get paid out they will STILL charge you more.

Have fun.

Pickwickpick · Dec 11, 2018

I agree with @YorkshireDave the chipboard flooring has got to be replaced, it won't be structurally sound and you'll be storing up expensive problems for further down the line otherwise. I had a job last year with a similar situation, they'd had a bad leak previously that they thought they'd got away and didn't realise this was why their floor had started to bow and was falling apart under the lino.

Its one of the reasons why I hate it being used for flooring, even the green stuff for bathrooms gets trashed by a leak.