What is a good rule of thumb for how wide to cut the trench when adding new drain/waste/vent plumbing to a foundation?
Here is a made up example rule similar to what I am hoping to find:
Start with 2x the width of the pipe and
add 1” for every 6” you need to dig down
I ask because I would like to rent a concrete saw for just a day to cut the outline for the trench to create a nice clean edge and then do the jackhammering/digging on days afterward and I’d rather not have to rent the concrete saw again (or chisel and leave a jagged edge) if I find I didn’t cut wide enough.
Best Answer
That's a good rule, if a bit over-complicated. For most residential work that's within 24" of slab level, 12-16" is plenty, assuming that it's placed accurately.
You can always bell out the trench under the slab a bit if needed for a large assembly. Of course, plumbers would always want more. :)