Soil Pipe Repair and Soil Pipe Replacement

The soil pipe, or soil stack, carries everything from your toilets, basins and baths down to the drain. When it cracks, leaks or has been badly altered, the answer is a repair or a soil pipe replacement rather than another clear-out. Soil stacks are part of the internal drainage work we cover under general plumbing. If your stack is blocked rather than damaged, see soil stack unblocking. Call 07427 195142 to talk it through.

Signs your soil pipe needs attention

• Damp patches, staining or drips on a wall or ceiling near the stack
• A sewage smell in a bathroom, cupboard or boxed-in corner
• Visible cracks or rust on an old cast iron stack
• Water marks running down the outside wall below a joint
• Loose brackets, or a stack that moves when touched
• A soil pipe leaking at a branch after a bathroom refit

Repair or replace?

Not every leak means a new stack. A single failed joint, a perished seal on a push-fit connection or a badly made branch can usually be cut out and remade, leaving the rest in place. That is the sensible option when the pipe itself is sound.

Soil stack replacement makes more sense when the pipe is failing along its length: an old cast iron stack that is cracked or corroded in several places, a stack that has been patched repeatedly, or one that no longer suits the bathrooms connected to it. Replacing it in one go is often better value than chasing leaks one at a time. We look at the whole stack, explain what we find and let you choose.

Cast iron, asbestos cement and plastic stacks

Older homes and tenements often have cast iron soil stacks. They are strong and quiet, but they rust from the inside and outside, and their joints open as the building moves. Some stacks from the mid twentieth century are made of asbestos cement, which looks like grey concrete pipe. These must not be cut or broken without checking first, and should be tested and handled properly before any work. Most modern stacks are plastic, usually PVC, which is light and easy to join but relies on seals and correct support.

A replacement is usually done in modern plastic pipe with new fittings for every branch. Where only part of a cast iron stack is replaced, a proper adaptor joins the new section to the old.

What soil pipe replacement involves

First we find where the stack runs, which fittings join it, and where it enters the underground drain. The fittings on the stack are put out of use while the work is done, so we agree timings with you in advance. The old pipe is removed in sections, new pipe and branch fittings are installed and secured with brackets, and each toilet, basin and bath is reconnected. The top of the stack is vented, through the roof or with an air admittance valve where that suits the building.

When everything is connected, we run water through every fitting and check each joint for leaks. If there is any doubt about the drain at the bottom of the stack, a CCTV drain survey shows its condition.

Inside or outside the building

External stacks are usually the simpler job, although scaffolding or a tower may be needed to reach upper floors safely. Internal stacks run through boxing, cupboards or floors, so panels may need to be opened and made good afterwards. Where a stack is hidden, it is worth fitting access points that make future checks and clearing easier.

Flats and shared soil stacks

In tenements and blocks of flats, one stack often serves several homes. The shared part is usually common property, so repairs or replacement may need agreement between owners, through the factor where there is one. Work affects the neighbours too, because their fittings may be out of use for a time. We can describe what is needed so owners can decide together. For larger alterations, check with the council whether a building warrant is required.

What affects the cost

The price of soil pipe repair or replacement depends on how much of the stack is affected, whether it is inside or outside, how many fittings connect to it, the pipe material, access at height, and how much making good is needed. A single joint on an outside stack is a very different job from a full internal replacement in a tenement. We give a price once we have seen the stack.

Questions