How much does it cost to replace cast iron pipes?

Question

Our Victorian terrace still has the original cast iron soil pipe and it is beginning to flake and leak at one joint. What would a plumber charge to replace the full stack with plastic?

Anthony · Answer

If that's the case the guttering may need replacing the old cast iron to plastic you can get cast iron replacement but a lot of money and maintenance painting them when the paint starts flaking so to  your question  about £500 if single storey a bit more if 2 storey

Steven · Answer

Depends on the length of the soil stack and what connections are needed

Benjamin · Answer

Replacing a full cast‑iron soil stack on a Victorian terrace with plastic normally costs £900–£1,800 in the North West — and Wigan tends to sit at the lower end of that range.
Let me break it down so you can judge whether a quote is fair. This is based on my area north west.

Typical cost for full soil stack replacement 
Standard job (most Victorian terraces)
£900–£1,300

Includes:
Removing old cast‑iron stack
Installing new uPVC stack from ground to roofline
New brackets, collars, and connectors
Reconnecting WC, bath, basin wastes
Making good around entry points
Labour (usually 1–2 days, 2 people)
This is the most common price band.

More complex jobs
£1,300–£1,800+  
If any of these apply:
Stack runs through a loft conversion
Awkward access or scaffolding needed
Multiple branch connections
Rotten or damaged wall fixings
Need to alter internal pipework
Old cast iron is seized and needs cutting out in sections
Scaffolding alone can add £200–£400 if required.

Why cast iron starts leaking at joints-
Victorian lead‑caulked joints eventually crack as the iron expands/contracts over decades. Once they start flaking, they rarely stop — so replacing the stack is the correct long‑term fix.

Does it need its own valve?
No additional valve is needed.
A soil stack is a gravity waste system, not a pressurised pipe.
The only “valve‑like” component is an air admittance valve (AAV) if the stack cannot vent above roof height — but most terraces vent externally, so you likely won’t need one.

Bottom line
Expect £900–£1,300 for a straightforward terrace replacement, and £1,300–£1,800 if access or complexity bumps the labour time.

Marvin · Answer

It would typically cost around £1000 to replace your stack with upvc. Depending on complexity and access

Gheorghii · Answer

Hi Tushar, the cost of replacing cast iron pipes can vary significantly depending on the length and diameter of the pipework, its location, access, and the amount of work required.

As a rough guide, the cost could be approximately £500–£2,500+, including labour and materials. For a more accurate quotation, I would need to see the pipework and understand the exact scope of the job.

Alan · Answer

Anywhere from £800 to £1,400 depending on fittings needed as there could be. Several boss fittings for sinks,baths etc and more than one connection for several toilets,2 storey or bungalow or 3 storey so factors play a huge part on cost etc Hope this helps.

Steven · Answer

it would be cheaper if you only need to replace the exterior part of cast iron pipes by plastic one. But it would cost you much more if the toilet is not just seat behind the exterior wall, otherwise, £500 could cover it.

Steve · Answer

I'd go for cast iron effect plastic as a replacement, but it's about 40% pricier. If it's for outside, that's the way to go. If it's inside, just use regular plastic. Price-wise, it's anywhere from £500 to £1500, depending on how tricky the job is.

Lee · Answer

I will have to have a look 1st but I could offer a quote for £240 per day or £35 per hour. If that's any good but would be better to have a look at the job.

How much does it cost to replace cast iron pipes?

Follow Us

Cookies

Manage Cookies

Essential cookies

Analytics & Tracking

Advertising