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How do you fill a hole in a concrete floor where an old 5" pipe came through ?

Hi - I'm not sure if I've selected the right trade as such but I'm looking for a bit of help/advice if anyone can help please? I've recently removed all of the redundant ducting from an old warm air heating system. On the ground floor the ducting went below the concrete floor and it looks like the origin builders got trigger happy on the breaker when creating the hole in the floor. There are two holes that need filling - One is located just inside the inner skin of the external wall and can just be filled up to floor level but was wondering what is required to get it there? Prep work, materials, damp proofing etc. The other duct came through the floor next to the soil pipe (again, just inside the inner skin of the external wall). How do I fill the hole and screed to floor level and leave an appropriate "clearance" around the soil pipe etc as I want to get the boxing around the soil pipe in the room as small and neat as possible? Many thanks for any/all help, much appreciated.

1 Answer from a MyBuilder Bricklayer

Best Answer

Hi Grant

Firstly widen the top of the hole slightly to create a wedge shape, then you drill the sides of the hole and insert first start twist ties, (which is effectively a brick tie) this will help keep the the two elements joined.

You then need to provide support for the concrete mix, depending on the distance to the ground you can loosely stack bricks as close to the bottom of the hole or you can use two small rectangular pieces of ply each 50% the size of the hole and secure using fast setting impact adhesive. The first can be put in place by hand the second will require a large screw so you can hold it in place.

Once you have secured a base either way, mix up a thick concrete mix using rapid set cement or a ready mixed fast set concrete. Leave it for an hour and then with a wet float smooth. That plug will never come out without breaking the floor around it.

Hope that helps!

Kind Regards


Answered 28th Sep 2020

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