Pitch fibre pipework

Developed in the mid-20th century, was created as a lightweight and flexible alternative to traditional materials like clay and concrete. Made from a combination of bitumen and cellulose fibers, it offered excellent resistance to corrosion and chemical damage. Its use became widespread in the 1960s and 1970s, particularly in drainage systems, due to its affordability and ease of installation. However, over time, concerns about its longevity and structural integrity led to a decline in its popularity, with many municipalities opting for more durable materials.

Delamination

The internal layers of the coal-tar-soaked wood fibre begin to peel away or "bubble" inward.

Cause

Constant exposure to hot, soapy water (from washing machines and dishwashers) softens the bitumen. This causes the layers to separate (delaminate) and creates internal blisters that snag debris and cause frequent blockages.

Total Collapse

In late-stage failure, the pipe loses all structural integrity and flattens entirely.

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Cause

 This is usually the endgame of untreated deformation or extreme external pressure. Once the pipe is no longer circular, it cannot distribute the load of the soil, leading to a structural "pancake" effect.

Common Pitch Fibre Issues

The failure of pitch fibre is rarely a single event; it is usually a progressive deterioration caused by the material's inherent lack of rigid structural integrity.

Deformation 

This is the most common issue where the pipe loses its circular shape and becomes "oval" or "egg-shaped."

Cause

Pitch fibre relies on the surrounding soil for structural support. Over time, ground movement, heavy surface loading (like a new driveway), or the softening of the pipe material causes the pipe to squash under the weight of the earth above it.

Root Intrusion

While clay pipes have joints every few feet, pitch fibre was often installed in longer lengths. However, the joints that do exist are often just "push-fit" collars.

Cause

As the pipe deforms, the joints open up. Tree roots sense the moisture and enter the pipe. Because pitch fiber is soft, roots can easily exert enough pressure to crush or tear through the pipe walls once they find a point of entry.