Utility room, damp from breached concrete slab.

[MadeUpName]

Been in my house a year. Noticed laminate floor degrading, lifted laminate and saw damp all around the concrete/screed that previously encased the CH supply, flow, and return pipes. Suspecting leak from pipes I chiseled and dug to expose them. No leaks, so I suspect the (non-slab) concrete, underlay and laminate had been sucking up the damp from the bare earth below the slab - pics attached. The utility room is reclaimed from part of the garage which is attached to the house. Property was built early to mid seventies.

Question is, how do I reinstate this and prevent damp problem from recurring?

I can't see any evidence of dpm under the slab and I'm not sure if what's left of the brick wall will complicate matters.
Would this work:
Protect pipes, backfill and compact with sand, add some sort of dpm layer, cover with screed?
Or would this just cause the damp to reoccur?

I'm also thinking it would be best to leave the joints at either end uncovered. Would having small voids at either end cause a problem once covered with laminate?

Cheers for any pointers.

 

[MadeUpName]

 

[MadeUpName]

 

[crazydaze]

Back Fill to level, Apply Liquid DPM - something like F-Ball F77 and then self levelling screed over the DPM.

Floor will 'breathe' through walls but should'nt be an issue so long as no excessive heavy damp issue and floor is 'breathing' it out (no leaks)

 

[Scally-Ho]

OMG, I had to look away from all that mickey mouse 'plumbing' in plastic. Yes, liquid DPM is the obvious answer

 

[MadeUpName]

Cool, thanks both.

 

[endecotp]

You’re going to insulate the pipes first, right?

 

[securespark]

OMG, I had to look away from all that mickey mouse 'plumbing' in plastic. Yes, liquid DPM is the obvious answer

The original plumbers were disgusted seeing all the "new" plumbing done in metals other than lead!