oh help! This is rot, for sure - but is it dry rot?? Bathroom floor.

[GlomOfNit]

We are, shall we say, rather lax about property maintenance and tend towards a 'shall we worry about that later' mindset. I know, this is very bad. And now it comes back to bite us on the bum!

House is single-skin brick semi, 1920's, ex-council stock. Has (rather cruddy) painted pebble dash on the exterior. We've been here almost 13 years. This is our en suite bathroom which previous owners put in, partitioning off a bit of the bedroom. The suite was horrible and a few years in (7 years ago??) we had it replaced, but NOT the shower tray or door, as those turned out to be non-standard size and very hard to source. Hence they are older and cruddier than the rest of the suite.

The vinyl flooring was fitted at the same time. The silicone sealant has since gone around the corner of the door frame but ... I didn't realise. Water has clearly been leaching round the hinge side of the shower door and seeping down behind the bust sealant. I had vaguely noticed that the vinyl floor in that corner was a bit discoloured but - hey. It was only a few inches across. Fast forward to this past week when I realised that a small patch of floor in that corner was ... bouncy. In fact, if you press on the vinyl it's sort of ... not there. 😱

I booked a guy to come in and replace the evidently rotten board, and he's coming tomorrow or wednesday. In the meantime, I carefully cut away the silicone seal and peeled back that corner of the vinyl, to find this. There's the dark rotting wood, yes. That's what's discoloured the underside of the vinyl. But there's also these white strands of mycelium/fungus. A frantic google seems to be divided on whether these white strands are wet rot, or dry rot. I don't know much about it, but I do know that if you have to have one of them, you do NOT want dry rot!

I'm in tears with anxiety about this. One of my recurring nightmares is when a house literally falls down around me from neglect, and I think our laissez-faire chickens are coming home to roost! Any crumbs of comfort to offer me while I wait for the man? (He's a plasterer and bathroom man, I asked round locally for someone who could help with replacing a rotting floorboard and he's done this sort of work.)

(pics hopefully, if not in post then in comments.)

Not easy to tell from the photos but likely wet rot as it doesn't look like it's spread beyond damp timber.

Dry rot only needs timber with a much lower moisture content than wet rot and will send tendrils in all directions looking for it including along/through masonry

But you know the floor has been leaking? And therefore wet rot surely?

Both can be started with damp timber, the main difference is dry rot is far better at spreading and has a much higher tolerance for drier (not dry) timber. Normally youd expect timber in a house to be significantly <15%

Dry rot only needs 20% moisture where wet rot needs 50%.

Yes, this was my thought - both types need a certain amount of moisture to germinate or get started but dry rot doesn't then need continuing wet conditions and can spread far, looking for more to eat, without it being damp.

I'm really, really hoping that this is wet rot! We had a scare when a minor roof leak (bad tile and leading in a shared gulley plus blocked drain pipe was causing water to pool and find a way through, onto and along a wooden roof beam that comes out in our bedroom ceiling) was associated with a tiny but rusty bloom of what I was sure were dry rot mould spores. but the roofing guy who checked the roof outside (and mended the leak) and inside checked the rafters, said there was absolutely nothing to be seen that looked like dry rot.

If the mycelium hasn't expanded beyond wood that has obviously got wet you can almost guarantee it is not dry rot.

What you are looking for with dry rot is mycelium well past any sign of wet staining. At the 20% moisture needed for dry rot the timber looks and feels dry which from what I can tell from your photos isn't the case.

I'm in the dark on my phone but that white stingy stuff looks like it might be partially decomposed/rehydrated adhesive. In any case I'd rip all the flooring off and get the sub repaired or replaced to a decent margin around any damage, seal the whole lot then new flooring on top.

It certainly doesn't look like dry rot, which has a distinctive brown-red powdery appearance and tends to 'bloom' from timbers unexpectedly.

I know a lot less about wet rot but the one thing it does have in common with dry rot, afaik, is that it stems from a specific fungus (a different specific fungus from dry rot).

Maybe your floorboards are just...a bit mouldy. I would dry them out and clean them up, then see what happens before panicking about either tbh.

I know what you mean, FrontEnd but it's not, it's very definitely organic and looks just like the characteristic white fan shape described/pictured on lots of online stuff about wet rot. Trouble is, I've seen this on pages about dry rot too!

I know that the 'mature fruiting bodies' of dry rot are horrible fleshy pinky beige bulgy things with rusty red spores, but the way dry rot spreads is via spider-webby filaments and I was freaking out a bit about this white fan stuff!

Bloke has popped in to have a look and thinks it'll (probably) be ok, the rotten boards are actually plyboard mounted on top of our floorboards (which are exposed in our bedroom and run under the flooring in the en suite - because of the ply and then the vinyl, the floor of the en suite is a tiny bit higher than the bedroom). He reckons the floorboards beneath are ok (how he knows this I don't know, but it's certainly true that there aren't any corresponding damp stains or anything at all on the ceiling below). He's going to remove the affected section of ply and replace it - I assume we'll have to let the area dry out first though.

I'm still feeling very spooked by this mould. Please don't shout at me, but are there any places you can send off a scraping of your household mould and get it ID'd?? Or is that entirely mad? :-D

I really don't think you need to panic.

Let's take the worst case scenario andxsay its dry rot. Cure the source of damp and it still cant spread to any timber unless it has a higher than 20% moisture which is virtually unheard of in any modern heated home without obvious signs of significant damp throughout the house.

50 years ago when expectations of internal decor and environment were very different it was a different story.

Unless you're decorating with limewash over wet walls, sleeping with coats over blankets and scraping ice off the inside of your bedroom windows in the morning you can relax