Backfill internal drain pipe

[j007]

My old clay drainage pipe was replaced with a new PVC pipe underneath my hallway. The hallway floor was removed and the ground was dug up in small sections. The new drainage pipe was put on a bed of shingles and then once the pipe was in place, it was covered in more shingles. The ground originally had hollow core slabs before damp proof membrane, insulation and screed. Can I simply pour concrete (or cement?) over the shingles to essentially backfill the gap in the hollow core slab that was broken through? Or do I need to put something first like ballast or some plywood before concrete? Please see the photo of one dug up section to see what it looks like currently.

 

[noseall]

My old clay drainage pipe was replaced with a new PVC pipe underneath my hallway. The hallway floor was removed and the ground was dug up in small sections. The new drainage pipe was put on a bed of shingles and then once the pipe was in place, it was covered in more shingles. The ground originally had hollow core slabs before damp proof membrane, insulation and screed. Can I simply pour concrete (or cement?) over the shingles to essentially backfill the gap in the hollow core slab that was broken through? Or do I need to put something first like ballast or some plywood before concrete? Please see the photo of one dug up section to see what it looks like currently.

You have concrete floor beams and not easy to repair. You are going to have to try and fix a bottom shutter beneath that floor, by slotting it under, pulling it up and either screwing through any available concrete or suspending/clamping it from above via S/S threaded bar etc.

clamp.jpg

• noseall
• 28 May 2023

Either way, it would be wise to poke some rebar down into those hollows when about half full with conc.