Pricing pages in this trade usually say “every job is different” and stop there. Cast Iron Oshawa publishes the ranges instead, because the shape of the job — not the postal code — is what sets the number, and a homeowner who knows the tiers can read a quote intelligently. The figures below come from what GTA drain specialists and industry cost guides publish for cast iron work; your written quote will price your actual house after a camera look at the pipe.
The four tiers
Sectional spot repair
≈ $1,600–$4,800
One failed length cut out and replaced with new pipe on shielded couplings. Legitimate when the camera shows the rest of the run still has wall thickness.
Partial stack replacement
≈ $3,000–$9,000
The vertical stack, or the stack plus the worst branches, replaced in ABS while sound sections stay. Industry guides put the average stack job around $6,500.
Full-house re-pipe
≈ $5,000–$8,000 typical
Every drain above the slab — stack, branches, vents — replaced in one project. Published full-replacement ranges stretch to $8,000–$18,000 for large or complex houses.
Buried sewer line + excavation
≈ $10,000–$25,000
The under-slab run and the lateral to the street, dug up or replaced trenchless. Covered in detail on the sewer line page.
What actually moves the number
- How many storeys the stack passes through. A bungalow stack is one straight run; a two-storey with a mid-height bathroom means more branches, more wall openings, more restoration.
- Whether the slab gets broken. Everything above the basement floor is normal plumbing labour. The moment the concrete saw comes out, you've moved toward Tier 4 money.
- Finished versus unfinished walls. An exposed stack in an unfinished basement is the cheapest version of this job. A stack buried in a finished mid-century wall assembly costs demolition and rebuild on both ends.
- Galvanized branch lines. If the kitchen and bathroom branches are 1960s galvanized steel, replacing the stack alone is half a job — and quoting them separately later is more expensive than doing it once.
- Access and disposal. Cast iron is heavy — a hub-and-spigot stack comes out in sections weighing what a person can barely carry, and it all has to leave the house and go to metal recycling.
What the cheapest quote in the pile tends to leave out
When three quotes are far apart, they're rarely pricing the same job. Before you compare bottom lines, check each one for: wall and ceiling restoration (some quotes end at “drywall by others”); the plumbing permit and inspection where the scope requires one; replacement of the galvanized branches versus stack-only; proper venting corrections — older houses often carry undersized or improvised vents that don't meet current code once the wall is open; and haul-away of the old iron. A camera inspection beforehand is the other guard-rail: it's typically a modest flat fee, and it means the quote prices what the pipe actually is rather than what the estimator hopes it is.
Why doing it planned beats doing it flooded
These numbers assume a scheduled job. A stack that fails first adds emergency call-out rates, water extraction, disinfection and rebuilding whatever the sewage reached — and because home insurance policies routinely exclude gradual corrosion as a maintenance issue, that add-on bill is often yours. The insurance and home-sale page covers that angle; the short version is that the $5,000–$8,000 planned job is the cheap version of this story.