PITCH FIBRE DRAINS: IDENTIFYING RISKS & EFFECTIVE SOLUTIONS
During a recent CCTV drainage inspection on the South Coast, we discovered that the majority of the drainage system was made from pitch fibre.
This is a potentially serious defect that requires attention.
Pitch fibre drain pipes were used between 1945 and the 1970s, but was mostly commonly used in the 1950s and 1960s as it was cheap, readily available and easy to work with. It is made from wood cellulose, impregnated with inert coal tar pitch and may contain asbestos, but this should be safe if left undisturbed.
However it is now considered a deleterious material as it only has a lifespan of 40 years, meaning any systems that currently use pitch fibre, now require attention.
At the end of it’s lifespan, it will flatten, bubble and eventually collapse, yet this would not be known until a serious issue occurs above ground. As the pipes are not visible above the surface and are only visible by a drainage cctv inspection, any deteriorating systems would remain hidden until a severe problem appears.
If a collapse was to occur, it would have serious costly and safety implications, not just to the building, but to people, assets, equipment and resources. Therefore it is best practice to replace, or rehabilitate in some circumstances, any pitch fibre pipes to avoid the risk of issues occurring.
On this particular site, we advised that it would be sensible to make allowance for future replacement of the pipes as a result of them being at the end of their lifespan.
If you manage or are acquiring property which was built between 1950 and the 1970s, it would be good practice to instruct a CCTV inspection to assess the system and learn if there are any pitch fibre pipes.
On many older sites, we still find pitch fibre drain pipes regularly as they were so frequently used, but now is the time to be considering a drainage inspection to proactively mitigate the risks that are failing underground.
