Currently, I have an issue with damaged plastic sheeting for our concrete slab and am seeking advice on how to proceed.
Background:
Earlier this year, we had a leak in a drainage pipe from the toilet in our bathroom located on the basement level. The insurance company was involved, and we had to jackhammer the slab to expose the drainage pipes.
Problem:
Our house is from 1979 and was built with plastic sheeting under the slab and foam plastic insulation over the concrete slab. Unfortunately, the plastic sheeting under the concrete slab was damaged when the removal crew jackhammered the concrete, resulting in a large hole in the floor down to the gravel. The builder suggests that this hole should be filled with leca balls, coarse concrete, and then overlaid with EPS concrete, leveled, and tiled without any repair or other action to address the damaged plastic.
Question 1: As I understand it, the purpose of the plastic is to prevent moisture from seeping into the concrete slab, is this correct? The builder claims here that the plastic is only intended to separate the gravel from the concrete...
Question 2: Should we repair the plastic layer before casting, and if so, is there any proven/preferred method for repairing this?
Overview
Close-up: Before the demolition, there was approximately 50mm foam plastic over the concrete then a subfloor panel.
