How to treat black mould - very old floorboards (pic)

[TheRhythmlessMan]

Renovating a 300+ year old cottage, ripped up the bathroom floor tiles that were on a suspended floor on these old floorboards.

The plan was to make this room a nursery but not so sure anymore having seen this mould! Unless anyone has any bright ideas?

We'll carpet over it but need to rid of it so it doesn't get worse/reappear.

(I know it'd be lovely to keep them exposed but they're not in great condition and will worry with baby crawling etc)

it's a bathroom. As usual, it's had water leaks.

Poke them with a flat screwdriver to see if they're rotten or wormy. If not, sand them. Don't use anything pointy because the holes will make the next person who looks, think it's worm.

If you're as fussy as me, have a carpenter take them up so you can treat the joists and the board with wood preserver.

Stain and varnish them if you want.

if you're going to carpet (courageous in a bathroom) fit WBP ply first or all the nail-heads and gaps between the boards will show and cause wear spots in your floor covering. Fasten it with just a few small screws so you can take it up next time someone leaves the bath running and you get a flood, so it can dry out. you don't have to do that under the bath unless it is draughty.

Here's the floor under my bath (pre fitting it).

It doesn't look like black mould to me. Just dirt which has got wet at some point. I wouldn't treat it with anything especially if the boards are now dry.