Plumbing in a Semi-Detached House

Two houses, mirrored

Semis in Mississauga, from the 1970s pairs around Cooksville and Malton to later ones in Meadowvale and Erin Mills, are usually built as mirror images. Each side has its own water service, its own meter and its own sanitary lateral, but the stacks often sit back to back against the party wall. That layout keeps runs short and tidy, and it also means sound, smell and the odd leak can travel through the wall in ways owners of detached houses never notice.

What tends to go wrong

• Utility rooms so tight the water heater, furnace, softener and laundry all share one corner and one floor drain
• Vent stacks crowded against the shared wall, so a blocked vent gurgles in both kitchens
• Side-by-side laterals where a root mass in one pipe often means roots in the other
• Original builder fixtures, including toilets and shower valves now forty years old

Working on a semi

We treat the party wall with respect: no opening it without knowing exactly what runs inside, and no heavy cutting that could crack block on the other side. When a drain backs up, we confirm which lateral is affected before cabling, because the cleanouts can sit within a metre of each other. If your neighbour has had a sewer line cleared recently, mention it on the phone; similar roots often explain both.

Water heaters in small rooms

Replacing a tank in a cramped semi utility room is a matter of planning the route out. We drain it fully, cut it free, walk it up the stairs and set the new unit on a pan with fresh shut-off and expansion tank. In tight rooms, a tankless unit on the wall can win back floor space, provided the gas supply and venting can carry it.

Where to look first in this house

Answers our Mississauga crew gives most