Damp/Wet floorboards

[SALL2009]

The floor boards at the edge of my cloak room keep getting wet / damp. It seems to increase after rain, but I can't how surface water could be getting there. The problem has been there for a while and as I'm doing the house up, I dug up the concrete that meets the floor boards from the cloak room floor. My plan was to put DPM between the concrete and the floor boards. But the wetness came back on the edges, after 2 days of no heating and some rain.
If you look at the pictures, there is a clear gap between the two floors. So I can't understand where the moisture coming from. I have removed a floor board and the soil below is damp. on lifting a piece of rubbish (tile) from the soil under the floor board. It had droplets of moisture. Could this be air ventilation issue? Can anyone give any pointers on what to try.

Untitled

• SALL2009
• 3 Jan 2011
• 1

Close up below. The joist right below the boards, doesn't seem damp. There is no heating in the cloak room and it does get very cold, could this be a cause?

Untitled

• SALL2009
• 3 Jan 2011
• 1

 

[JohnD]

I'd suspect excessive moisture caused by a leak. Take up the floor and feel around. Is the void ventilated with airbricks? If not, expect rot. If the wet patch is on the boards where the plastic flops onto them, it'll be condensation caused by the excessive damp.

 

[SALL2009]

There have been leaks previously, but from what I can tell, all issues have now been fixed. The joists seem solid. There are air vents in the building. I'll check if they are blocked.

So could the moisture from previous leaks, be causing the current damp. Should I lift some floorboards and try to dryout the soil?

 

[JohnD]

yes, and also to search for wetness and ventilation.

 

[SALL2009]

yes, and also to search for wetness and ventilation.

Thanks,

Would it be worth hiring a dehumidifier for a week or so or heating on full should do the trick?

 

[JohnD]

If the wetness is on or under the floor, I think ventilation is the answer. Your heating will not have much effect down there.

 

[SALL2009]

well there is a bit of damp patch on the wall on the left side of the damp floor boards.

 

[JohnD]

leak, penetrating, or condensation?

 

[SALL2009]

I don't think it can be a leak. Because we have fixed a leaking stack pipe, with new one. I guess, it could be the moisture from the previous leak or condensation. Because the clock room does get very cold and ever water pipes freeze in the cloak room (or leading to it from the kitchen). Are there any sort of heating options for such areas?

 

[SALL2009]

I have lifted a couple of floor boards and the soil under neath is all wettish. There are 3 air brick at the back of the house and 3 in the front. I have unblocked these (front ones seemed blocked with mud).

There is a through lounge from the front of the house to the back. In the middle of one of the rooms, there is a wall to support the floor joists. There are around 3 inch gaps between each bricks of this wall. Are these enough gaps to circulate air from front of the hosue to the back (assuming there are same gaps in the wall in the other room.)