Semi checklist
- 1Party wall pipesnote runs along the shared wall
- 2Drainsseparate or shared lateral
- 3Leakscheck both sides when water appears
- 4Main valveyour own shut-off
- 5Neighbourscoordinate when work affects both
01Leaks that travel
Water follows framing and pipes. In a semi, plumbing often runs along the party wall, so a leak on your side can show up in the neighbour's basement or vice versa. We trace it to the source before opening walls.
If both houses have water, check both sides.
| Common in | Malvern, Dorset Park and other areas |
|---|---|
| Shared drains | Some older pairs share part of a lateral |
| Leaks | Can travel along the party wall |
02Shared laterals
Some older semi pairs share part of the sewer lateral to the street. If both houses back up, the shared section may be blocked. Clearing it benefits both.
03Renovations
Moving plumbing near the party wall needs care, especially with fire separation requirements.
04Noise through the wall
Drain noise from the neighbour's side is common in semis with cast-iron or plastic stacks along the party wall. Plastic drains are louder. Wrapping exposed plastic stacks with insulation during a renovation helps.
05When only one side backs up
If only your house backs up, the problem is almost certainly on your own branch. A camera inspection from your cleanout shows where your line joins any shared section.