Sewer Pipe Lining Pros and Cons

The case for lining

Nothing above the pipe is disturbed

This is the reason sewer pipe lining exists. A house lateral runs under the front yard, the driveway, the sidewalk and often the street; the drains under a slab run under the kitchen, the bathrooms and the laundry. A trench through any of that costs more to restore than to dig, and some of it, a mature tree, a stamped-concrete patio, a tenant's business, a city arterial, cannot be restored at all. A liner goes in through the cleanout and comes out at the main, and the surface never knows.

It is a one-day job on most laterals

Camera in the morning, jetting, liner in, cure, reinstatement, final video, and the family uses the bathroom that night. A replacement of the same pipe is two to five days of open trench with the sewer out of service for all of it, plus whatever time the concrete and landscaping take afterward. For a restaurant or an apartment building the difference between an overnight liner and a week-long dig is the difference between staying open and closing.

The new pipe is jointless, root-proof and leak-proof

Roots enter a sewer at joints and cracks. A cured liner has neither; it is one continuous piece from end to end, and the cured resin is not a material roots can penetrate. Groundwater that was leaking in through open bells, which is what fills basements and overloads treatment plants, stops. The surface inside the liner is far smoother than clay or cast iron, so the few millimeters of diameter the liner takes up are more than repaid by the lower friction, and the line carries as much flow as before or more.

It is engineered for 50 years

The wall thickness of a cured-in-place liner is calculated, not guessed. ASTM F1216 sets it from the pipe's diameter and depth, groundwater head, soil load, the ovality of the host and the long-term flexural modulus of the cured resin, on a 50-year design basis. The earliest installations are approaching that age and still in service. The sewer pipe liners page has the material numbers.

It costs less than replacement on nearly any built-over line

On completed residential jobs where the owner had a dig bid first, lining came in 28 to 49 percent below it. The sewer pipe lining cost page has the jobs and the per-foot math. The saving comes from the restoration that the trench requires and the liner does not.

The case against lining

A liner copies the host pipe, faults included

This is the hard limit and the source of most bad lining jobs. The liner inflates against whatever shape the old pipe has. A belly stays a belly. A section that has lost its slope keeps its lost slope. A joint stepped sideways by more than the liner's wall can bridge becomes a narrow spot. A crushed or collapsed section will not let the tube through at all. Each of those is a case for pipe bursting, a sectional point repair or an open-cut section, and the comparison is spelled out on the pipe lining vs pipe bursting page.

It cannot upsize

If a four-inch lateral is undersized for what the house now puts into it, or a municipal main is undersized for the development above it, lining does not help; the liner is slightly smaller than the host. Bursting can pull a larger pipe through; a trench can lay one.

Every connection has to be reinstated

The liner covers every branch that joins the run. A robotic cutter reopens each one afterward, guided by camera, and a missed or off-center reinstatement is the most common residential complaint. The number of connections is also the biggest driver of under-slab pricing. An installer should tell you how many there are before the job and show you each one reopened on the final video.

Resin, odor and cure can be mishandled

Polyester and vinyl ester resins carry styrene, which has a sharp odor during cure that can enter a building through dry traps or an open cleanout. Epoxy, the residential standard, does not. Any resin that is under-cured, or that migrated during the cure and left a thin spot, or that was pushed into a liner cut too long for the run and folded into a fin, produces a liner that is difficult to remove and expensive to fix. The quality of the job is the quality of the crew, more so than with a new pipe laid in a trench where everyone can see it.

Not every pipe material lines the same way

Orangeburg that has already gone oval, cast iron that has rusted through along the bottom for most of its length, and concrete with a missing invert each need a decision about whether the host can still serve as a form. The clay sewer pipe lining guide goes through each material and the point at which it stops being a lining candidate.

When the trench still wins

A shallow lateral in open lawn, with no driveway, no slab, no trees and no street in its path, can be cheaper to replace than to line, because the restoration cost that makes trenching expensive is absent. A line with a long belly, or one that has lost its slope along most of its length, needs to be relaid regardless of cost. A pipe that needs to move, because a new addition sits on top of it or the connection to the main is being changed, needs a trench. And a pipe that a camera cannot be pushed through, because it has collapsed, is not a lining candidate until the collapse is fixed by other means. The honest installer with both a lining rig and an excavator on the truck says which, and shows you why on the screen.

How to decide

Get the camera inspection first and watch the footage with the contractor. Ask for the belly, the offsets, the collapse and the roots to be pointed out and located on the surface. Ask which repair each defect calls for, and whether the run is a candidate for a full liner, a liner with a spot repair at the one bad joint, a burst through the crushed section and a liner through the rest, or a trench. Then get a second quote from an installer who can also do the other method. The state guide for where you live, reached from the pipe relining near me page, shows the verified installer for your state where one is listed.

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