Drainage tips
The problem with pitch fibre drainage pipes
Pitch fibre pipes were first used for drainage in the UK in the 1950s, because they were cheaper than conventional fired clay pipes; their manufacture ceased in 1984. They are made of wood fibre impregnated with coal tar and are susceptible to delamination of their inner surface, tree root encroachment and damage from the passage of heavy vehicles.
Their average life is reckoned to be at best some 60 years, but the failures in these pipes have also been exacerbated by poor initial installation; unlike clay pipes, pitch fibre pipes require a granular bed and higher compaction and this was not fully realized before 1973!
So what happens is that pitch fibre pipes can become deformed over time, no longer keeping their round profile, looking more like a squashed sausage and causing frequent blockages and eventually total failure of the drainage system.
Where a building survey or an RICS Homebuyer service is being undertaken, Blocksaway Ltd. highly recommend the addition of a CCTV survey of the drainage before purchase, often at a cost of as little as £125; insurers are seeking to minimize their liability for pitch fibre drainage problems, and it is well worth establishing the condition and nature of pipework prior to purchasing a property.
Squashed pipe
Root ingress
Bulging drain causing frequent blockages
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Dont block your own drains
Recently we were called out to a property in St Ives, it was on the face of it a fairly standard job, blocked drain causing sewage overflow in the garden.
We arrived, the owners of the property explained the problem and then left us to it while they popped out to the shops. The normal procedure in such a case is to find the inspection chamber (manhole) down the line from the overflowing area and use high pressure water jetting to clear obstructions in the drain, allowing waste to flow correctly. On this occasion we identified that the drain followed an L shaped pattern but could not find the inspection chamber manhole cover where we expected it to be. We were just about to go to plan B when the owner arrived home, we explained that we were looking for a manhole cover in the garden but couldnt find it. The owner knew exactly why we couldn’t find it, it had recently been removed and replaced with a sunken water feature complete with Pea gravel!
Once the Pea gravel had been cleared from the manhole the problem was resolved.
