How much does it cost to replace a cast iron drain stack during a Vancouver condo bathroom reno?

Replacing a cast iron drain stack during a Vancouver condo bathroom renovation typically costs $3,000 to $8,000 for the plumbing work alone, though the total can climb to $10,000 to $15,000 or more when you factor in strata requirements, access complications, and restoration of finishes in a multi-storey building.

The cost range depends on several critical factors. A partial stack replacement — removing and replacing only the section within your unit, typically one to two storeys — runs $3,000 to $5,000 for the plumbing labour and materials. The plumber will cut out the corroded cast iron section, transition to modern ABS (Acrylonitrile Butadiene Styrene) piping using approved Fernco or Mission couplings, and reconnect all fixture drains. A full stack replacement that extends through multiple floors is significantly more expensive at $6,000 to $12,000 or more, but this is usually a strata-initiated project rather than an individual owner's responsibility since the drain stack is typically common property.

The strata dimension adds significant cost and complexity. In most Vancouver condos, the main drain stack is classified as common property under the Strata Property Act, meaning the strata corporation is responsible for its maintenance and replacement. However, the branches connecting your individual bathroom fixtures to the stack are typically your responsibility as the unit owner. Before proceeding, you need to determine exactly where strata responsibility ends and yours begins — this varies by strata plan and bylaws. Getting this wrong can mean paying for work the strata should cover, or doing unauthorized work on common property.

Strata approval is mandatory before any drain stack work begins. You'll need to submit a renovation application that includes a detailed scope of work from a licensed plumber, proof of contractor insurance (minimum $2 million liability is standard for Metro Vancouver stratas), WorkSafeBC clearance, and often an engineering assessment. The strata may require a plumbing report or camera inspection of the existing stack before approving replacement. These pre-approval costs — engineering assessment ($500 to $1,000), camera inspection ($300 to $600) — add to your total budget.

Many of Vancouver's older concrete towers from the 1960s through 1980s — particularly in the West End, Kerrisdale, Marpole, and parts of Burnaby and New Westminster — have original cast iron drain stacks that are reaching the end of their 50 to 70-year lifespan. Signs of a failing cast iron stack include slow drains, rust-coloured water, sewer odours, visible corrosion or pitting on exposed sections, and water stains on ceilings below bathrooms. If your building's stacks are in this condition, a bathroom renovation is the ideal time to address the drain piping within your unit.

Access is the biggest cost variable in condo stack replacements. The drain stack is typically buried in a wall cavity or chase between units. Accessing it requires opening walls, which means demolition and reconstruction of drywall, tile, or other finishes — often in a bathroom that's already being renovated, but sometimes in a neighbouring unit's space as well. If access through an adjacent unit is required, expect additional costs of $1,000 to $3,000 for wall repair and finishing in that unit, plus the coordination headache of scheduling with your neighbour.

A plumbing permit from the City of Vancouver or your local municipality is required for drain stack replacement, typically costing $200 to $500. The work must be inspected before walls are closed up. All plumbing must comply with the BC Plumbing Code, and the licensed plumber must ensure proper slope (minimum 1/4 inch per foot for horizontal runs), adequate venting, and correct pipe sizing for the fixture load.

Budget an additional $1,500 to $3,000 for restoration work after the plumbing is complete — patching and finishing drywall, repainting, and potentially retiling areas that were opened for access. If you're already doing a full bathroom renovation, much of this restoration is incorporated into the overall project, making it the most cost-effective time to tackle a failing drain stack.

Always hire a licensed plumber with specific experience in Metro Vancouver condo drain stack replacements — the strata documentation requirements, access logistics, and coordination with neighbouring units require a contractor who understands the process.