Sadly you won’t probably know if you have pitch fibre drains until you have a problem. And then the fun and games start with your insurance company possibly refusing to cover the cost of repair.

Sadly with the life expectancy of pitch fibre drainage only approximately 40 years we are now finding more are more customers are calling us with drainage problems caused by pitch fibre.
What is pitch fibre?
Pitch fibre was developed in the 1940’s when materials were in short supply and was made from wood cellulose impregnated with coal tar with asbestos added to strengthen the material. Due to it being cheaper and a more lightweight alternative to the traditional vitrified clay drainage it was used in much of the post war building until the 1970’s when plastic drainage took over.
What are the drawbacks?
Pitch fibre collapses when exposed to external pressure and delaminates internally producing blisters when hot water and fat, oil and grease are regularly poured down the drain. Equally prolonged contact with water can cause the drain to blister and deform.
The photo shows a section of pitch fibre pipe with a large blister which was causing blockages in the line.
So what can you do?
If you have a problem then we would initially conduct a CCTV survey to understand in detail the extent of the damage. Depending on the CCTV results we would recommend a couple of solutions:
Excavate and replace with new plastic pipework but we prefer to do this only where the pipe cannot be sorted using the no-dig repair solution.
Ideally we would undertake a no-dig repair as this is quicker and cheaper. Also known as a CIPP repair (Cure In Place Piping) this option involves specialist re-rounding of the existing pitch fibre line to remove any blisters or deformities. This is then followed by the insertion of a liner, which, when impregnated with epoxy resin, hardens to provide a new, structurally sound line inside the pitch fibre line.
We provide a guarantee of 10 years but this solution has a life expectancy of at least 50 years.
Each option has it’s benefits and sometimes a partial excavation is required where there are junctions but these requirements are fully clarified using the CCTV survey.
The image shows the deformed pitch fibre line before and after lining.
So if you have or are considering buying a house built between about 1940 and 1965 then we suggest you have a CCTV survey done to check whether the drainage is pitch fibre and whether you have any problems.
If you have pitch fibre drainage we also suggest you check your insurance policy regarding cover as this varies enormously from company to company.
If you are buying a house we strongly recommend a CCTV survey of the drainage anyway to provide peace of mind about what you are taking on. Repairs can be costly regardless of the type of drainage and damage caused by ingress of roots is very common. Sadly this is often not covered by insurance companies so it’s worth checking the state of your drainage beforehand.
Obviously if you have no problems then you could just leave things as they are. However, pitch fibre is now past it’s life expectancy so you are literally sitting on a ticking time bomb …….