Mould under floors boards

[t1gerwoods]

HI i lifted my floor boards on which had been raised of a concrate floor by 25mm, it had damp course put down then 25mm wooden battons, kingspan 25mm then sheets of uniply. it had slight marks of mould where the 25mm battons were, i think the battons might have been damp when the floor had been layied. what can i do, should i get a dehumidifier to try and drt it all out.

 

[HERTS P&D]

First I would check for any pipes nearby, then try a dehumidifier for a week or so. It could be moisture in the concrete or timber that has not been able to escape.

Andy

 

[jadzy]

i'd go for your timber battens are thermal bridging down to the cold concrete slab. so moisture from the kitchen is getting down and condensation is occuring there, resulting in damp and then mould.

that or you have no or not enough air flow through the 25mm void you made with the battens, if the kingspan is sitting on top.

 

[stevethejoiner]

If the battens were damp when put down they should have dried out, if there is an airflow that is. How is the 25mm gap ventilated?
If no ventilation then it could be the original timber batten moisture content or condensation from humidity in room above or both. A dehumidifier will not permanently cure this problem. You should either ventilate or completely fill the 25mm void with either dry sand/cement or additional insulation material. But that will be a lot of work. If you do nothing you could end up with dry rot as that bugger loves damp unventilated spaces.