Hi, currently doing a renovation on a 70’s townhouse. The ground floor screed (about 2” deep) has a 9-12” gap around where the soil stack runs into and under the ground floor, at the back corner of the house. The level here is about 2-4” lower than the rest of the screed and appears to be just loose sand around the soil stack.
What can I use to patch this so that I don’t get damp problems. Would Sika Waterproofer (or similar) added to a mortar/cement mix mean I won’t get damp rising though this patch. Another option I was considering was to patch an initial layer over the loose sand, then paint liquid dpm over this, before levelling some more mortar over the top to match in with the level of the rest of the screed. Again would this work?
Thanks in advance
Steve