Internal drain cover cause of rising damp?

[silverfx]

After moving into his retirement bungalow, my father discovered mould in an extension bedroom, and threw out the underlay and carpet which was going to be replaced anyway. Applied antifungal wash to the concrete floor. The plaster was mouldy above the skirting board for about two feet upwards, so I took hammer and chisel to it for him and chipped off the skim coat plaster about 5mm deep.

Applied anti-fungal wash to the plaster but yet to skim it (been told that an anti-fungal plaster should be used?). That was several months ago and no mould has returned, so skimming soon

We think the cause was condensation rather than rising or penetrating damp; just a cold room where previous occupants may have dried clothes etc. However, taking up the carpet revealed an internal drain cover, fitted by a previous owner, where two out of four corner screws have corroded and gone greenish.

Question: Is the screw corrosion due to the damp underlay and carpet from condensation, or due to damp rising up from the drain below either around the screw holes or the cover seal?

Hoping it's not rising damp, but prepared to replace the cover with a new double sealed one if necessary, or as a cheaper fix, apply silicone around the existing screws and all around the cover seal if that made it rising-damp tight.

Any ideas much appreciated!

 

[Newboy]

They are brass screws and have slightly corroded. It's a screw-down sealed cover and you shouldn't have problems with moisture escaping from the cover.

I'd be inclined to go with the problem being from another source. It's unusual to see condensation problems starting at floor level and rising (usually see mould at high level and in the corners with condensation) - is there any chance that there has been any sort of flooding (water leak etc.) in the room?

 

[silverfx]

Hey, thanks for the reassurance about the sealed cover.

I agree about condensation usually causing mould at a high level and in corners and I wonder if it can cause damp and mould at floor level under circumstances.

Regarding a flood, don't think there's been, but who knows, there could have been one years ago (pretty low land) with flood water entering an air brick in the room 1 foot up, maybe flooded the room, soaked the carpet and it never recovered?

 

[foxhole]

Mould occurs at any level where ventilation is poor, could have been furniture there allowing mould to get hold, check the previous owner has not blocked any vents.

 

[silverfx]

A previous flood or condensation could have been the cause then. Well, I'll be keeping as little furniture in there as possible, using the vents, and praying for no floods!

Thanks guys