Fungal infection in the ply (fruiting bodies)

[Thomas C King]

We've found a couple of mushroom fruiting bodies growing out of the floor plywood, about two metres apart. The first thing to do is to find out why the ply has got so damp (a leaking pipe, I suspect). After that is rectified, does the ply need replacing because the fungus has succesfully infected the plywood. Or, is it sufficient to apply something to the ply? I am thinking that the infection will have affected the ply's integrity, but I don't know if that's an issue.

 

I know there have been a few threads on this topic, but I haven't seen (may have missed) the remedies that worked. Opinions welcome, thank you

Edited November 7, 2020 by Thomas C King

[BEngo]

If it is damp you quite probably have dry rot. (Paradoxically, dry rot loves unventilated wet timber.) RIP the ply out and treat everything for about 2 or 3 feet  around with a good clear wood preserver.  

 

N

[Tracy D'arth]

Yes, rip it out, dry rot will travel across steel, brick, concrete even plastic to find a water source, it will be under the floor in the ballast too.  You can buy proper fungicide to kill it.

 

[Sea Dog]

2 hours ago, BEngo said:

RIP the ply...

Not wasted on me!

 

[David Mack]

Yes you must remove any damaged ply, which means in practice you have to go back to the next support timber beyond so that the joint between new and old is properly supported.

But the spores which cause any fungal attack are in the air anyway. So if you have not sorted out the source of the damp the problem will return, although liberal use of preservative clearly helps.

Sorting out the damp may well involve areas which are not directly affected by the fungus e.g. provision of proper under-floor ventilation.

[Chris Lowe]

If the wood looks perfectly good on the outside but the core is all soft then it's certainly dry rot.