CIPP pipe lining: what it is, how it's installed, and what it costs

CIPP is short for cured-in-place pipe, and the industry also calls it pipe lining, sewer relining, structural lining or simply a liner. The result is a new pipe formed inside the old one: a flexible tube of felt or fibreglass, saturated with a thermosetting resin, positioned inside the host pipe and then hardened in place. Once it cures it is a stand-alone pipe that carries the structural load, with the old pipe acting as little more than a mould around it.

That is the part worth holding on to when reading a quote. A liner is not a coating or a patch over a crack. It is a new pipe, and the reason it can be installed without digging is that it goes in soft and hardens afterwards.

The sequence is much the same from one contractor to the next, and knowing it makes a quote far easier to read.

1. The line is cleaned — usually hydro jetted — because a liner presses against whatever is on the pipe wall. Roots, scale and grease have to come out first, and this is often a separate line on the quote.
2. A camera run confirms the pipe is a candidate and measures the length and diameter to size the liner.
3. The liner is saturated with resin, a process called wet-out. It is time-sensitive once mixed, which is why crews work quickly at this stage.
4. It is installed either by inversion — turned inside out through the pipe under air or water pressure — or pulled into place and then inflated. Inversion presses the resin outward against the wall; pull-in-place is often used for shorter runs and spot repairs.
5. It is cured, by leaving it to set at ambient temperature, by circulating hot water or steam, or with a UV light train pulled through it. UV and steam cure fastest; ambient is slowest and cheapest.
6. Any branch connections the liner covered are reopened from inside with a robotic cutter — this is called reinstatement, and a line with several branches costs more because each one has to be cut back.
7. A final camera run records the finished liner. Ask for that footage as well as the before footage.

This is the constraint that decides whether lining is even on the table, and it is the one most often skipped in a sales conversation. A liner takes the shape of what it is pressed against, so the host pipe has to still hold a shape worth copying.

• Good candidates: pipe that is cracked, leaking at the joints, letting roots in, or corroded but still round and continuous.
• Not a candidate: a collapsed section, a badly crushed or deformed pipe, or a line the camera cannot get through — there is nothing to line against.
• Not a fix for a belly. A liner laid through a sag reproduces the sag in a slightly narrower pipe, and the line still holds water. This is the single most common mis-sale in sewer work.
• Severe offsets at a joint can stop a liner passing, or leave a ridge that catches debris.
• Orangeburg is a judgement call — some contractors line it, others refuse because the host is too soft to press against.

Why a liner doesn't fix a belly→

A liner has a wall thickness, so the finished pipe is narrower than the one it went into — commonly a few millimetres of wall, so roughly a quarter to a half inch off the internal diameter on a residential line. On a 4 inch lateral that is a small proportion of the cross-section.

In practice the loss is usually offset by the finish. The new surface is smooth plastic where the old one was corroded cast iron, scaled, or rough clay with root-filled joints, and a smooth pipe carries more flow at the same diameter than a rough one. A lined line that still drains poorly afterwards is a sign the problem was grade or a sag, not diameter.

Check whether grade was the problem→

Lining is priced per foot, plus the work that has to happen around it. The per-foot figure quoted rarely includes the cleaning, the camera runs, the access pits or the reinstatement of branches, which is why the total can be well above length times rate.

Planning ranges assembled from published 2025–26 trenchless contractor cost guidance, consistent with this site's other repair figures. Not quotes.

Price your run and check a quote against it→

The question comes up constantly, and the answer is not simply that it is trenchless. The liner and resin are engineered materials bought by the foot. The wet-out is time-critical skilled work. The crew arrives with a jetter, a camera, a reinstatement cutter and curing equipment, which is a lot of capital for one driveway. And the whole job is priced with the risk that the camera finds something mid-job that stops the liner going in.

What it buys is a line replaced without excavating the yard, the driveway or the street — and where restoration would have been the largest part of a dig, lining is often the cheaper answer overall rather than the premium one.

Manufacturers and contractors commonly quote a 50-year design life, and the municipal record for CIPP in larger sewers broadly supports a multi-decade service life. Treat it as a design life rather than a warranty: what you are actually offered is the contractor's own warranty, which is typically closer to 10 years, and which is only as good as the company standing behind it.

The realistic failure modes are installation faults rather than the material wearing out — a liner that was not pressed fully against the wall, a wrinkle at a bend, a poorly reinstated branch, or resin that cured badly in cold ground. All of them are visible on the post-installation camera run, which is the reason to insist on it.

Many CIPP resins are styrene-based, and curing releases a strong, sweet chemical odour that can enter a building through a dry trap, an open cleanout or an unsealed connection. It is a well-documented nuisance around municipal lining projects and a common surprise for homeowners, who are rarely warned about it.

Sensible precautions are simple: pour water into every floor drain and unused trap beforehand so none are dry, keep the house ventilated during and after the cure, and arrange to be out for the day if anyone in the household is pregnant, asthmatic or sensitive to solvent odours. Ask the contractor which resin and cure method they use — styrene-free and UV-cured systems exist and produce far less odour.

1. Can I see the camera footage that shows lining will work on this pipe, not just a written summary?
2. Is there a belly on this line, and if so how does lining address it?
3. Is the price per foot, and does it include cleaning, camera runs, access and reinstating branches?
4. Which resin and cure method — and is it styrene-based?
5. How many branch connections will be reinstated, and is each priced?
6. What is the warranty, in writing, and how long have you been trading?
7. Will you camera the finished liner and give me that recording?
8. What happens to the price if the liner cannot be installed once you start?