Older neighbourhoods have the most root problems because their sewer laterals are usually vitrified clay or concrete laid in short sections with many joints sealed by mortar, jute or early gaskets, and because their trees are now fully mature. Every joint is a potential entry point. Clay itself resists corrosion well; the joints fail, so repairs that seal or eliminate joints work best.
- Vitrified clay resists chemical attack and can last a very long time; its weakness is the joint, not the wall.
- Short pipe sections mean a joint roughly every 0.6 to 1.2 metres, so a 20-metre lateral can have 20 to 30 potential root entry points.
- Mortar-packed and jute-packed joints are highly vulnerable; later factory compression joints resist roots better but still fail with movement.
- Mature boulevard and yard trees in older areas have had decades to find those joints.
- Transitions from old clay to newer plastic, often from partial repairs, are frequent root entry points.
01 /Why do older neighbourhoods have more root problems?
Older neighbourhoods combine the two ingredients roots need: jointed pipe with aging seals and large, mature trees. Houses built before plastic sewer pipe became common typically have laterals of vitrified clay or concrete, and the trees planted when those neighbourhoods were new are now at full size, with root systems that have had decades to explore every trench.
It is not simply that the pipe is old. Vitrified clay is fired ceramic that resists most chemical attack and can remain structurally useful for a very long time. What ages badly are the joints: the mortar, jute, oakum and early sealing compounds used to connect short pipe sections. When those seals shrink, crack or rot, the pipe starts leaking moisture at every connection, and roots follow.
02 /How were clay and concrete sewer laterals built?
Clay and concrete laterals were built from short, rigid sections joined with bell-and-spigot connections. The spigot end of one pipe sits inside the flared bell of the next, and the annular gap between them was filled with a sealing material. The type of seal depended on the era and the builder.
| Joint type | Approximate era | Root resistance | How it fails |
|---|---|---|---|
| Cement mortar packed into the bell | Early 1900s to mid-century | Poor | Mortar shrinks, cracks and falls out; gap opens |
| Jute or oakum with mortar or bitumen cap | Early to mid-century | Poor | Organic fibre rots, leaving a void |
| Hot-poured bituminous or sulphur compounds | Mid-century | Fair | Becomes brittle, cracks with ground movement |
| Factory-applied compression joints (polyurethane or PVC rings) | Roughly 1960s–1970s onward | Good when intact | Deflection, settlement or ring degradation opens a path |
| Concrete pipe with mortar or rubber gaskets | Mid-century | Poor to fair | Similar to clay; crown corrosion from hydrogen sulphide in some conditions |
Eras overlap and vary by region, municipality and builder, so treat the table as a guide to what a camera may find, not a statement about any specific house. The camera report will say what your pipe actually is.
03 /How many joints does an old lateral have?
Quite a lot. With sections roughly 0.6 to 1.2 metres long, a 15-metre lateral from the foundation to the property line has somewhere around 12 to 25 joints, and a 25-metre run to a street main can have 20 to 40. Each one is a candidate for root entry.
That arithmetic drives repair decisions. A camera might show roots at three joints this year, but the other joints share the same age and seal type. A sectional repair at three spots may be cost-effective for now, yet it leaves many similar joints that could fail next. Full lining addresses every joint at once, which is why it often wins on old clay laterals with multiple root sites. See permanent root fixes.
04 /What makes transitions and partial repairs a weak point?
Where a previous owner or contractor replaced part of a clay lateral with PVC or ABS, the connection between the two materials is often the new weak point. The outside diameters differ, so the transition relies on a rubber coupling with steel bands. If that coupling was poorly fitted, lacked shear protection, or the old clay end was cracked, roots and soil can enter.
- Transitions often sit exactly at the edge of a previous excavation, where backfill is loose and roots travel easily.
- Settlement of new backfill can drop one side, creating an offset at the coupling.
- The clay bell at the transition may have been cut or broken during the repair.
- Inside the house, similar transitions between cast iron and plastic can also leak, though roots rarely reach them.
On camera, a transition appears as a change in pipe colour and surface texture, often with a slight step. Roots bunched at that step are a classic finding in older homes with partial repairs.
05 /What else goes wrong in old clay and concrete lines?
Roots rarely act alone in old pipe. Decades of ground movement, frost, root growth and settlement produce a set of defects that often appear together on the same camera run.
| Defect | Link to roots | Repair implication |
|---|---|---|
| Offset (displaced) joints | Root girth and ground movement push sections apart | Lining works if the offset is modest; large offsets may need replacement |
| Longitudinal and circumferential cracks | Roots widen existing cracks; cracks admit roots | Lining bridges cracks while the pipe holds shape |
| Sag or belly | Soil washed through open joints can create voids and settlement | Lining keeps the sag; replacement or bursting fixes it |
| Broken or missing pieces | Heavy roots can break weakened bells | Needs assessment; may require excavation |
| Crown corrosion (concrete) | Separate process driven by sewer gases in some conditions | Assess wall thickness before lining |
06 /What should owners of older homes do?
- Assume jointed pipe until proven otherwise
If your house is older and has never had its lateral replaced, plan as though it is clay or concrete.
- Get a baseline camera inspection
Clear the line first if roots are present, then film the whole run to the main or property line with a footage counter.
- Count the problem joints
Note how many joints show roots, infiltration or offsets, and where any transitions sit.
- Map trees against the route
Include boulevard and neighbour trees. Score them with the Root Risk Calculator.
- Decide the strategy
Few problem joints: point repair plus monitoring. Many joints but good shape and grade: full lining. Sags, collapses or severe offsets: bursting or replacement.
- Coordinate with the municipality
Ask about the condition of the public portion and whether the city has any program for older laterals.
For planning costs across cutting, lining and replacement, see the root removal cost guide. When you have footage and want contractors to price the same scope, request quotes.
07 /Is clay pipe worth keeping if it has roots?
Often yes, as the host for a liner. Because vitrified clay walls resist corrosion, a clay lateral that is still round and on grade can make an excellent host pipe for CIPP lining. The liner seals every joint and the clay provides the surrounding structure.
What a lining job on a root-damaged clay line involves, from cleaning the joints back to the wall to sealing the liner ends, is covered in sewer lining for tree roots.
Clay is not worth keeping when it is collapsed, badly broken, severely offset or sagging, or when the diameter is too small for current needs. Those lines are candidates for pipe bursting or open-cut replacement. The camera, not the age of the house, should make that call.
FAQQuestions people ask
How long does clay sewer pipe last?
The clay itself can last a very long time because it resists chemical attack. The joints are the weak point, and root intrusion at joints usually drives repairs long before the clay wall wears out.
Why do clay pipes get roots more than PVC?
Clay pipe comes in short sections joined every 0.6 to 1.2 metres, often with mortar or jute seals that fail over time. Solvent-welded plastic has far fewer joints and those joints are chemically fused.
Can a clay sewer line be lined?
Yes, if it still holds its shape and grade. Clay laterals are common hosts for CIPP lining, which seals every joint in one installation.
Is concrete sewer pipe better than clay?
Not for roots. Concrete laterals have similar short sections and joint types, and concrete can also suffer crown corrosion in some sewer conditions.
My house is from the 1950s. Is my sewer clay?
It may well be, but eras vary by municipality and builder, and many laterals have had partial replacements. A camera inspection is the only reliable way to know.
Are the joints between clay and PVC a problem?
They can be. Transition couplings from earlier partial repairs are frequent root entry points, especially if the coupling was poorly fitted or the old clay end was cracked.
NETWORKGo deeper across the HAUSE Sewer network
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Sewer pipe materials by era in Canadian homes: clay, cast iron, Orangeburg, concrete, ABS and PVC, how each one fails and what it looks like on camera.
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How to clean vitrified clay sewer pipe safely: root cutting at joints, jetting pressure and nozzles, offsets and cracks, and when clay needs repair.
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