Breaking the Basement Concrete for Bathroom – DIY Plumbing

Learn how to break a concrete trench to run plumbing lines in the ground for future plumbing. The Coach shows you how in the basement of a renovation project.


Plumbing Helper says:

From one x-pro to all those watching. This is a dirty, dusty, and labor intensive job…then you have to dispose of the concrete. I truly hope this is Construction Coach’s house. Some recommendations for those watching:
1) plastic off the local area to help localize the dust, floor to ceiling, creating a ‘room’. Concrete dust will go everywhere…especially into the furnace, even if it is off.
2) wear a dust mask, please, the entire time.
3) double/triple the width of the trench at the exposed pipe. The Y fitting that needs to be attached needs the extra room for attaching. [Process is to cut out a section of the existing pipe (about 12-14 inches long) and ‘splice’ in a Y fitting using rubber couplings (preferably “banded”). The Y branch of the fitting is at a 45 degree angle to normal. If there needs to be additional, angled pieces, this locates the Y fitting up or down the existing pipe and more pipe will need to be exposed under the concrete.]
4) The chipper is at least a $400 tool (cheap one). His is probably $1000. Renting one will make the job much easier. A small jack hammer will do it too. The least expensive way to do it: 1) draw your trench lines on the floor, 2) ‘hammer-drill’ holes in a circular pattern thru the concrete, 3) then bang away with a sledge. The heavier the sledge, the better. The sledge will bounce off the floor for the first several hits..depending on the concrete. This process is several hours. Cutting the ‘score line’ does make for a cleaner trench and easier to finish when pouring the concrete. A lot of care needs to be taken when hitting the floor in the general area of the pipe. Pipes today are normally plastic. Pipes of yesteryear at cast iron. The cast iron pipes are brittle compared to the power behind a sledge. If you have a cast iron pipe, use the hand grinder and diamond blade to make a clean cut when splicing. Yes, you can splice a plastic fitting into a cast iron pipe and using rubber couplings (preferably banded).
5) Also remember, and the plumber will know this, there may need to be a back-flow valve put into the new branch line, somewhere. This is common plumbing code for all states and below-ground basements. Back-flow valves require a way to access it through the floor, so plan for this with the trenching. There are expensive cast aluminum and cast iron covers for this (commonly seen in commercial building floors), and I commonly used treated wood frames and plastic solid covers for residential jobs.
6) I normally filled the new-pipe-in-trench hole with the small pieces and fines from the concrete I broke out. Less waste to dispose.

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