blackened floorboards dues to old leak

[frankjones]

Hi while replacing some carpet I've found a couple of blackened (does that mean moldy?) chipboard floorboards. These were damaged serveral years ago by leaky tiles in a neigbouring bathroom. The source of the leak in the bathroom was fixed long ago and the bathroom replaced.

The damaged chipboard area is about 2ft square beside a wall. Its black and patchy with a pattern. The chipboards have not blown too badly, feels reasonaby stable and it doesnt seem to smell or be damp. I could easily lay a carpet over it and no one would know it was there.

My question is- is this likley to give any future problems with mold or damp. Also, ths is going to be the room for our soon born baby - are there any likley health dangers if its fully covered up?

[The Natural Philosopher]

IME no, it won't be a problem.

Soaked chipboard swells, goes black, but if dried out, although its not perfect, it usually goes back together fairly well.

If its seriously structural, replace it, but if its just a small patch, probably sand it and put a soaking sort of resiny varnish over it or even PVA. That will stop it leaking dust spores and stabilise any crumbly bits.

[BigWallop]

The Natural Philosopher wrote in news: [e-mail]:

I'll second that. If the surface of the flooring feels like loose sawdust, then it's better to replace the board because it has lost a bit of its integrity. If it all feels solid and not springy / spongy, then it's not worth worrying about. These boards are treated for mould resistance, because houses do have moisture in the air that penetrates naturally into the fabric of the building.

The board has blackened because of an old dampness problem, but it sounds like, from what you describe, it has not caused the flooring to be comprimised in a major way. Try sanding off the surface and see if some of the normal colour comes back to it. If it does, then forget it.

An example of how robust these floors are. A new build project. Flooring left for a whole week in a cold damp room. Boards showed blackening on both sides. The boards were allowed to dry out properly in a heated room for a few days. laid and sanded to bring the colour back, and all was perfect.

Cost seventeen quid to hire a floor sander for half a day, but it was a lot cheaper than the 700 hundred quid to replace the boards. :-) Don't tell anyone I told you that. LOL

[ConfusedCarbuyer]

Dear Frankjo On our pro bono terms - free advice - you indemnify! "The chances are that the blackness is a mould, probably Aspergillus niger. Opionions differ as to the health risks but if it were my floor I would not sand it off but would wash off with a mouldicide any surface spores, let it dry well and then seal it with PU varnish or the like. This is all assuming structural integrity which can be determined by a simple deflection test (jumping on it!)and having an observer see if there is any more movement than on sound boarding. That is most unlikely given the circumstances described." Chris

[Andrew Gabriel]

I wouldn't use PVA. It's quite good at supporting mould.

[The Natural Philosopher]

Only if its still damp.