Advice on bathroom floor damaged by leak - replace?

Bluegold1

Hello, I'm hoping for some advice/opinions to someone (me) with zero knowledge on flooring after a bad leak I’ll try to link to a photo.

I had a leak from behind/under my bathroom toilet and didn't notice it for quite some time due to it being under vinyl flooring. Eventually pulled back the vinyl and discovered the soaking wet (chipboard?) flooring which has mostly dried out very well now. A plumber fixed the leak but pointed out that the floor is soft/spongy and if pressed with foot could push down slightly (although he said won't collapse - I'm in a top floor flat so I guess he assumed the subfloor between flats is strong?). He says it may leak again as any pressure on the toilet due to the soft/spongy floor could easily loosen it from pipe again. Actually, 2 weeks on there is still small amounts of water coming from under the toilet so the leak isn't fully sorted so I'll need to get that fixed. The immediate wet patch around the toilet that is still wet(due to the continued leak) is soft and a screwdriver can easily break little bits off (it can't do that on the now dried remainder of floor). I'm thinking to ask the plumber not only to fix the leak but for a quote to replace/fit new flooring immediately under toilet (and the other 2 panels immediately there also that are most water stained). I'm worried it's damaged or unsafe and could collapse despite his assurance. I plan to move in a year or so, so don't want to pay for the whole floor to be redone if not needed - is it as simple as cutting out that bad 'wood' and replacing? Some of it is alongside wooden sink unit and bath and could run under there - ok to just get the exposed parts replaced? Or would the whole floor need replaced? He'd mentioned a new floor could be £600. I'm aware the existing chipboard or whatever may not be best long-term (especially for bathroom) but don't mind that as l have a limited budget and like I said hope to move in the long term. I expect any new buyer would anyway just fit a whole new bathroom as it's 20yrs old and quite dated looking. Grateful for any opinions/advice before I contact for quotes. 

Bluegold1

This is the photo, almost 2 weeks after leak “fixed”

Swasterix

Yes- only the damaged section needs to be replaced. It would be a case of cutting the existing bit out half way over a joist (taking care not to hit any potential cables/pipes beneath, or damage the joist), and replacing with a new section. Should be a fairly quick job and really cost no more than the cost of a replacement board plus labour. Wouldn’t be too difficult to do yourself if you’re that way inclined. Sure there’ll be YouTube videos out there you could watch!

Obviously it goes without saying that the leak should be sorted first and foremost. 

Good luck!

grumbler

Swasterix said:

Yes- only the damaged section needs to be replaced. It would be a case of cutting the existing bit out half way over a joist (taking care not to hit any potential cables/pipes beneath, or damage the joist), and replacing with a new section.

The boards, most likely, are tongue&groove and not expensive. If possible, it's worth replacing whole boards or parts.

Bluegold1

Thanks guys, any idea of reasonable price to replace 2 or 3 boards?

grumbler

A 2.4x0.6m tongue&groove board is £11-£13 at B&Q, depending on the thickness .

Workwise, it's difficult to say because the most damaged board goes under the cabinet and the skirting board.

Cutting, like Bluegold1 suggested, can be a simpler option. In this case it's probably better to use a bigger board.

As a side note, I guess the vinyl flooring was laid around the toilet. Ideally, it has to be under it, covering the entire floor area, so that small leaks can't get under the vinyl. At least all gaps around the toilet and on the sides of the room have to be sealed reliably.

FreeBear

grumbler said: A 2.4x0.6m tongue&groove board is £11-£13 at B&Q, depending on the thickness.

For a bathroom, use a moisture resistant grade of chipboard - Might cost a tad more, but should be more tolerant of an occasional leak.

Tip - Drill pilot holes through the chipboard and then use screws to fix it down. Nails are never a good idea, and if you don't pre-drill, bits of chipboard may get pushed in between the joist and board. This will result in a perpetual squeak & creak every time someone sits down.

grumbler

FreeBear said:

For a bathroom, use a moisture resistant grade of chipboard

I wanted to suggest this, but couldn't find any at B&Q.

Crumble2018

We had exactly the same issue this year - toilet was fixed to a tiled boxed off area, and we didn't realise until our vinyl flooring started to discolour. We ended up having half of the floorboards replaced, but it mean't removing all the boxing and a complete re-build of it, as the damp boards went underneath it.  So we replaced the sink and toilet at the same time.  £600 for flooring sounds steep - the new boards and ply laid over the top cost us about £50, and the labour charge for the whole job, including rebuilding the boxing, tiling and fitting new sink and toilet was £700.

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Bluegold1

Thankyou so much everyone for the advice. Thanks for the pics Crumble - very helpful

danrv

I have a similar issue with one small section of chipboard flooring in my bathroom.
A bidet used to sit here and the wood as become springy, probably due to over flowing or a leak.
Hope this is still relevant to the original post but was wondering, as they overlap, how to fit a section of tongue and groove chipboard (22mm) in between good boards.