subfloor Damp around new water pipe

[tonyramponi]

I recently had a lead water supply pipe replaced in my 1930's Semi with a MDPE pipe. While running an electrical cable I've had the floor back up and noticed that the sub-floor around the pipe entry is damp. The subfloor doesn't appear to be damp elsewhere - Just around the new pipe: -

I think the hole made in the subfloor/foundation has just been back filled with soil. Not sure how much or a problem this is as the sub-floor is well ventilated and there is an air brick not too far from the pipe entry point.

I'm currently planning on excavating the pipe back out, wrapping it in a bit of DPM and then cementing up the hole in the subfloor. Is this a bad idea?

 

[Notch7]

I assume this is a suspended floor: in which case the concrete is just an oversite capping with no damp membrane.

my guess is the the loose backfill just allows an easier route for damp than the concrete


surely That blue pipe visible is just a conduit and the water pipe is inside - in which case no need to wrap just concrete it

 

[tonyramponi]

Thanks for the response. I had a bit of a prod around and the ducting ends just below the surface so the pipe is exposed where i'll be putting the cement.

Yep, its a suspended floor. I have the same thought that the topsoil is an easier path for the damp.