When CIPP Lining Won’t Work?
At Ontario Pipe Lining, cured-in-place pipe lining is what we do every day. We’re licensed installers of Nu Flow’s patented lining technology and proud NASSCO members, and our crews line sewers under homes and commercial buildings across Ontario. So you might expect us to tell you lining fixes everything. It doesn’t, and we’d much rather say so up front than sell you a repair that lets you down a year or two later.
Here’s how we see it. When CIPP lining won’t work, it’s almost always because the old pipe can no longer support the new one. A fully collapsed section, a deep belly, or a joint that has slipped badly out of line all fall into that camp.
Below, our team walks through each of those, what we look for on the camera, and what we recommend when lining is off the table.
CIPP Lining Limitations Start With the Old Pipe
CIPP stands for cured-in-place pipe. On an Ontario Pipe Lining job, a resin-saturated liner goes into your existing sewer, a rubber bladder presses it against the old walls, and the resin hardens into a brand-new pipe inside the old one. (If you’d like the full step-by-step, here’s how CIPP lining works.)
As NASSCO members, we work from the same guidance the rest of the industry uses. The NASSCO Pipeline Rehabilitation Matrix lists two limits for CIPP that matter here. The pipe has to be free of crushed or collapsed sections and of any spot that has lost more than 40% of its opening. And after lining, the line and grade of the old pipe stay exactly as they were.
That second point is the one most homeowners never hear about, so we always explain it before quoting a lining job. More on that below.
Can a Collapsed Sewer Pipe Be Lined?
Short answer: not the part that has collapsed.
A liner needs two things: an open channel to travel through and a wall to cure against. Where a pipe has caved in, you have neither. There’s no way to push a liner through packed soil, and even if you could, nothing would hold its shape while the resin sets.
Partial collapse is a different story. A pipe that has cracked and pushed inward but still has most of its opening may still take a liner. NASSCO’s 40% figure is a helpful outer limit, though in a 4-inch residential line we get cautious well before that. A badly deformed spot can also stop the liner from passing cleanly, which is its own problem.
What we usually recommend is a hybrid. The collapsed section gets dug up and replaced with new pipe. Then our crew lines the rest of the run, which is often sound apart from cracks and roots. You end up with one small excavation instead of a trench from the house to the street.
We met a lot of homeowners who never heard about this middle option. They were told it’s lining or a full dig, nothing in between, and that simply isn’t true for most partial failures.
Bellied Sewer Line Repair: Why a Liner Follows the Sag
A belly (some people call it a sag) is a low spot where a stretch of pipe has sunk below the rest of the line. Sewers run on gravity, and the usual rule of thumb is about a quarter inch of fall for every foot of pipe. In a belly that slope reverses, so water and waste sit in the dip instead of moving on.
Most bellies come from soil settling or washing out under the pipe, or from poor bedding when the line was first laid. You’ll notice the symptoms long before you see the cause. Slow drains. Clogs that come back a few weeks after every cleaning. On camera, a pool of standing water that never quite drains.
Here’s the catch with lining. The liner hugs the old pipe. If the old pipe dips, the new one dips right along with it. No lining contractor can line a sag out of a pipe, and that includes us.
When our camera finds a belly, we tell you how deep it is and whether the lining still makes sense. Honestly, sometimes it does. A shallow belly that holds an inch of water and has never caused a backup is a very different animal from a deep one that keeps clogging. If that pipe is also cracked or full of roots, lining can still stop the leaks and the root growth. We just make sure you go in knowing the dip stays.
For a real sagging sewer pipe fix, the low section has to be excavated, the bedding underneath corrected, and the pipe relaid on a proper slope. Lining and pipe bursting both follow the old pipe’s path, so neither one fixes the grade.
Offset Sewer Pipe Joint Repair: How Far Out Is Too Far?
A lot of the sewers we inspect in older GTA homes, clay ones especially, were built from short sections joined end to end. Over decades, shifting soil and tree roots can push those sections out of line so the lip of one sits above or beside the next. That’s an offset joint.
Small offsets are routine and not a problem for lining. A liner smooths right over them, and flow usually improves because the lip that used to catch paper and grease disappears behind one continuous wall.
Big offsets are where things go wrong. NASSCO’s technical advisory council has said CIPP handles small and medium offsets well, but once an offset eats up roughly 30 to 40% of the pipe’s opening, wrinkles and defects start appearing in the finished liner. At 40% or more, their advice is to repair the joint first. A wrinkle might sound cosmetic. It isn’t, really; it’s a ridge inside your sewer that snags waste, the very thing you paid to get rid of.
Separated joints are a cousin of the offset. Here the sections have pulled apart, leaving open soil in the gap. A narrow gap can usually be bridged. A wide one gives the liner room to balloon outward into the void as it cures, leaving a bulge and a thin spot in the wall.
When we find one or two badly offset joints, we’ll usually recommend repairing those spots first and lining the rest of the line afterward. A pipe with serious offsets every few feet is telling us something else, and we’ll tell you plainly: it probably needs replacing.
Other Reasons a Pipe Might Not Qualify
Collapses, bellies and offsets get most of the attention. A few other conditions decide it too.
Pipe material. The Nu Drain system we install is approved for clay, concrete, cast iron and other metals, PVC and fiberglass, in diameters from 1.5 to 12 inches. You can read more about how our lining process works on our technology page. That list covers the large majority of residential sewers around Toronto, where older homes tend to have clay or cast iron.
Orangeburg, or “no-corrode” pipe, is the one to watch for. It’s basically wood pulp and tar pressed into a tube, and it went into some Canadian homes in the 1940s through the 1960s. While it’s still round, lining may be possible. Once it starts to oval or blister, it often can’t survive the cleaning that has to happen first, and replacement is the safer call. Edmonton’s utility, EPCOR, gives homeowners essentially the same advice.
Obstructions that won’t clear. Every lining job starts with mechanical cleaning. If roots, heavy scale or an intruding pipe can’t be cut back, the liner can’t get past.
Access. We need a way in, usually a cleanout or the stack. This is rarely a deal-breaker, but it does shape the plan.
Is My Pipe a Candidate for Pipe Lining? How We Decide
We don’t guess. Every job starts with a sewer camera inspection, and on lining jobs we clean the line and run the camera a second time before anything goes in. Cleaning often uncovers damage that roots and buildup were hiding, and we’d rather find it then than halfway through an install.
On the video we’re looking at the pipe material, how round it still is, the slope, every joint, and any spot where the opening narrows. (We go deeper on what a sewer camera can spot in a separate post.) Here’s roughly how the findings sort out:
| What the camera finds | Can it be lined? | Usual approach |
|---|---|---|
| Cracks, roots, leaking joints | Yes | Clean, then line |
| Minor offset joints | Yes | The liner smooths over them |
| Severe offset (roughly 30 to 40% of opening lost) | Not as is | Repair the joint, then line |
| Partial collapse, most of the opening intact | Often | Judged on video case by case |
| Full collapse | No | Replace that section, line the rest if sound |
| Shallow belly, no repeat clogs | Possibly | Lining seals it but the sag stays |
| Deep belly with recurring backups | No | Excavate and re-grade the low spot |
| Orangeburg that has lost its shape | No | Replace |
The top of that table is the good news. Most of what we see in GTA homes is in the first two rows: cracked sewer pipes, root intrusion and tired joints are exactly what lining was built for.
After the inspection you get to see the footage yourself. If a pipe isn’t a good candidate, we’ll show you where and why.
Sewer Pipe Too Damaged to Reline? Your Options
At Ontario Pipe Lining, we’d rather give you an honest no than a liner that won’t last. Knowing when CIPP lining won’t work is only useful if you know what comes next, and in most cases the choice isn’t a simple pipe lining vs excavation decision. There are really three routes.
1. Spot repair, then line the rest
This is the most common answer for a single collapse, one deep belly or a couple of bad joints. The damaged section is dug out and replaced, then the remaining pipe is lined. One small hole, and the rest of the line gets a new structural pipe with a long service life. (Curious how long? Here’s our breakdown of CIPP lifespan.)
2. Pipe bursting
A bursting head is pulled through the old pipe, cracking it outward into the soil while new HDPE pipe follows right behind. It works on pipes that’s too far gone to line, including fragile Orangeburg. The trade-offs: it needs a pit at each end, it suits fairly straight runs, and like lining it follows the old pipe’s path, so it won’t correct a belly.
3. Full excavation
Digging up and relaying the whole line is the only way to reset the grade along its entire length. It’s also the most disruptive and usually the most expensive option once driveways, walkways and landscaping are put back.
If most of your line is sound, the spot-repair-plus-lining route usually costs less and disturbs less than a full dig. Our page on trenchless Sewer Line Replacement covers what that process looks like and typical pricing.
Not Sure What’s Going On Down There?
You don’t have to figure out on your own whether your pipe is collapsed, bellied or just cracked. That’s what the camera is for.
Book an inspection with Ontario Pipe Lining and we’ll show you exactly what’s in your line, tell you straight whether it’s a lining candidate, and walk you through what makes sense if it isn’t. If you go ahead with lining, we credit the $300 inspection fee back. Knowing when CIPP lining won’t work is part of doing the job right, and it’s a big part of why homeowners across the GTA trust us for sewer repair in Toronto and beyond.
Call 905-442-5235 or contact us online to book.
Frequently Asked Questions
Can every damaged sewer pipe be fixed with CIPP lining?
No. Most cracked, leaking or root-filled pipes can. The main exceptions are fully collapsed sections, deep bellies, severely offset joints and Orangeburg pipe that has lost its shape.
Can you line a fully collapsed sewer pipe?
Not the collapsed section itself. There’s no opening for the liner to travel through and no wall for it to cure against. That section gets dug up and replaced, and the rest of the line can usually be lined if it’s otherwise sound.
What is a bellied or sagging sewer line?
It’s a low spot where part of the pipe has sunk below the rest, so water and waste pool there instead of draining. Slow drains and clogs that keep coming back are the classic signs.
Will lining fix a belly in my sewer line?
No. The liner follows the shape of the old pipe, dip and all. It can seal cracks inside the belly, but only excavating and re-grading that section removes the sag.
How bad does a pipe offset have to be before lining won’t work?
Industry guidance from NASSCO says liner defects start to appear as an offset approaches 30 to 40% of the pipe’s opening, and at 40% or more the joint should be repaired first. In small residential lines we judge each joint on the video rather than relying on a single number.
How do you know if my pipe is a good candidate for lining?
At Ontario Pipe Lining, a camera inspection tells us. We check material, roundness, slope and every joint, then inspect again after cleaning, since cleaning can expose damage that wasn’t visible the first time.
Can a partly collapsed section be dug up and the rest lined?
Yes, and it’s one of the most common fixes we recommend. You get one small excavation instead of a full trench.
What are the options if my pipe can’t be lined?
Three, mainly: replace the bad section and line the rest, pipe bursting, or full excavation and replacement. Which one fits depends on how much of the line is damaged and whether the slope needs correcting.
Does lining work on clay, cast iron and Orangeburg pipe?
Clay and cast iron, yes. They’re the most common lining candidates we see. Orangeburg can only be lined while it’s still round and firm; once it deforms, replacement is usually the better choice.
Why would a contractor recommend lining a pipe that can’t be lined?
Usually because lining is the only service they sell, or the inspection was rushed or skipped. Sometimes the homeowner just badly wants to avoid digging. Protect yourself: ask to see the video, ask what the liner will not fix, and get that answer in writing. At Ontario Pipe Lining, that conversation happens before we quote, not after.