BonnieW7

Thank you for the advice, that's very helpful. One additional question: if the pipes turn out to be bare copper, would it be advisable to cover them with a fairly thick foam pipe insulation sleeve before placing the repair mortar? My thinking is that the insulation would create a small separation around the pipe and allow for thermal expansion and contraction without the copper being tightly bonded to the repair material. Would that be considered good practice in this situation, or would simply wrapping the pipes with duct/gaffa tape be sufficient? Given that there is only around 20 mm of cover above the pipes, I'd be interested to hear how you would normally accommodate pipe movement when carrying out this type of repair.

Hello everyone, I'm looking for some professional advice regarding a floor repair issue in my kitchen. Approximately 10 years ago, a plumber completely redid the plumbing system in my house. To install the new pipes, he cut through part of the concrete floor, routed the pipes underneath the floor, and then backfilled and repaired the area before reinstalling the flooring. I've noticed that a small section of the floor (approximately 25 cm x 25 cm / 8–10 inches square, under vinal adessive tile) has started to sag and crumble. This area is directly above the plumbing pipes. My suspicion is that the concrete or repair material placed over the pipes was too thin, or that the fill underneath has settled over time, creating a void. The floor has not yet completely collapsed, but it appears to be heading in that direction. One concern is that this area is located in a regular walkway. If the floor eventually gives way completely, someone could step directly onto the pipes, potentially damaging or breaking them. A few additional details: The finished floor is covered with approximately 2.5 mm vinyl flooring. There appears to be only about 20 mm (3/4 inch) between the top of the pipes and the underside of the floor/concrete above. I do not currently know whether the pipes are PEX, multilayer, copper, or another material... probably copper. My current repair idea is: 1. Remove the vinyl flooring. 2. Remove all loose and damaged concrete/fill material. 3. Inspect the pipes and determine the extent of any void. 4. Fill any voids with a non-shrink structural grout. 5. Install a 4 mm stainless steel plate extending beyond the damaged area and bearing on sound concrete around the perimeter. I am not sure if this step in needed.. any thoughts? 6. Apply a thin layer of repair mortar above the plate. 7. Reinstall the vinyl flooring. My objective is to distribute foot traffic loads onto the surrounding concrete and protect the pipes from direct loading. Questions: Does this seem like a reasonable repair approach? Would you recommend a different method? Is the stainless-steel plate unnecessary if the void is properly filled? Are there any concerns with using non-shrink grout around plumbing pipes? If only 20 mm of cover exists above the pipes, how would you repair this area professionally? Is there a better material than a steel plate for this application? Any advice from plumbers, builders, or concrete repair specialists would be greatly appreciated. Thank you in advance.