Damp coming through floor

[Fastmonkey]

Having just self levelled an uneven floor this weekend I checked to see if it was all dry last night and noticed a small ( 12" by 6" approx) patch of damp in the corner of the floor. Now I remember seeing this area before just after construction but put it down to drying out / spilt water etc but obviously this is not the case. There is nothing coming through the walls it is just a small area rising up through the floor.

I was hoping to lay a laminate floor down soon with the correct damp proof membrane. Can I "get away" with doing this, maybe putting a damp proof sealant first or am I asking for trouble ?

Sorry should add this is not new construction it is an old lean too that has been extended to make a study and downstairs toilet.

Any help / advice would be much appreciated.

 

[WoodYouLike]

I was hoping to lay a laminate floor down soon with the correct damp proof membrane. Can I "get away" with doing this, maybe putting a damp proof sealant first or am I asking for trouble ?

If you don't know the cause of the moist then yes you are looking for trouble.
Any water pipes in that area?

 

[Fastmonkey]

Thanks for your response. As far as I can tell there are no water pipes in the area, and it is very sporadic it is only the 2nd maybe third time I have seen it in the last couple of months.

How can I best find out the source of the damp ?

 

[WoodYouLike]

Is it near outside wall? And does it happen after heavy rain? Then perhaps water is coming through from garden/patio/outside?

 

[Fastmonkey]

Yeah it is on an outside wall but there is no evidence of penetration from the wall, guttering run off or anything so can only presume it rises up from underneath the floor, and you might be right actually it does seem to be after heavy rain.....................

 

[WoodYouLike]

Have you checked if any air-vents (if that's the proper name) are blocked?