Basement Plumbing and Rough-Ins

Breaking the slab is the more permanent answer. We saw cut the concrete, break it out, dig the trenches, run new ABS DWV at the required fall, tie into the existing main, backfill and patch. The result is ordinary gravity drainage with standard fixtures and nothing to service afterward.

The honest part is what it costs you in disruption. It is loud for a day or more, and dusty whatever we do with plastic and containment. The spoil comes out of the house by bucket, and the basement is a work site for the duration. The patched slab is structurally fine, and it will always show as a scar if you pull the flooring up.

A macerating or up-flush system is the alternative when the main sits too high or the disruption is not worth it. Far less demolition, a much shorter install, a workable bathroom. In exchange you get a pump with a cutting blade that needs power, needs service eventually, and has hard limits on lift and run. It is also particular about what goes into it, and wipes will jam it whatever the label says. For a powder room used a few times a week it is sensible. For a rental suite bathroom used daily by tenants, gravity drainage is worth the concrete work.

Where the slab is up but the main is still too high, fixtures drain by gravity into a sewage ejector pit and the pump lifts the discharge to the main. The basin gets a sealed lid, a 2 inch vent to atmosphere, and a check valve plus an isolation valve so the pump can be pulled without draining the line back in. We use solids-handling pumps from Zoeller and Liberty. A sewage ejector is not a sump pump, and the two pits must never be cross-connected.

While the floor is open, a backwater valve is worth discussing. It is a normally open valve in the building drain that closes if the municipal sewer surcharges during a storm, which is the mechanism behind most basement sewage backups here. The City of Toronto has run a basement flooding protection subsidy covering part of this kind of work, but the terms change, so check the current program before counting on it.

Floor drains need a trap like any other fixture, and a trap that dries out lets sewer gas into the room. That is what people smell in a basement closed up for a season. A trap primer tied to a nearby fixture keeps it wet. Where a primer is not practical, a jug of water down the drain every couple of months works.

Basement apartments in Toronto are permitted, and plumbing is one part of a larger approval covering fire separation, ceiling height and egress, all outside our scope. We rough in to the drawings, pull the plumbing permit and meet the plumbing inspector. Someone else, usually a designer or permit consultant, leads the overall application, and any plumber offering to handle the whole suite approval is promising something they do not control.

What we do flag is loading. A second kitchen, bathroom and laundry in a house built for one of each puts real demand on the existing stack and water service. An old undersized service shows it as pressure drop the moment two fixtures run at once, and a 3 inch stack that has been fine for decades can behave differently with more fixture units.

Laundry rough-ins are simple but easy to get wrong. A recessed washer box keeps the hoses from being crushed behind the machine, and standpipe height and trap depth are set by code rather than preference. Put a floor drain in the room if you can.