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4 inch waste pipe running through the subfloor..?

skimonkey · 2025-05-06 15:24:28

My builder has laid a 4" waste pipe for our new utility/extension sink that runns across the utility floor to the external wall and connected to an existing back inlet gully to the sewer pipe. the run is approx 3m long and about 60cm in from the utility side wall gully connection like this which connects to sewer pipe -…

06-05-2025 04:24PM

#1

skimonkey

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Join Date: July 2010

Posts: 4

My builder has laid a 4" waste pipe for our new utility/extension sink that runns across the utility floor to the external wall and connected to an existing back inlet gully to the sewer pipe. the run is approx 3m long and about 60cm in from the utility side wall
gully connection like this which connects to sewer pipe - https://www.goodwins.ie/products/Back-Inlet-Gully-Trap-Grid-110mm.html

However I realise that the waste pipe will lie in the middle of the sub floor when it is poured. ie top one inch of the waste pipe will be sticking out of the subfloor with the rest in the subfloor.

The subfloor is to be 4" thick. The existing sewer pipe outside is about 6" lower than the gully back inlet so in theory the waste pipe has room to be lowered albeit it would require a different connection.

This seems like a problem but the builder says its fine.
Any advice?

Post edited by skimonkey on May 6

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