Tree root intrusion

Tree root intrusion is one of the most common causes of recurring drainage problems in London. Roots seek out the moisture and nutrients within a drain and exploit any imperfection at a joint or hairline crack to enter the pipe. Once inside, they form fibrous masses that catch wipes, paper and grease, leading to blockages and surcharge. North London streets lined with mature sycamores, limes and London plane trees are particularly affected, especially where original Victorian clay drains run close to mature specimens. Engineers usually address common causes by cutting roots mechanically or with high pressure jetting, then carrying out a CCTV drain survey in accordance with BS EN 13508-2. Long term solutions often involve patch repair, no-dig relining with cured-in-place pipe or, where damage is severe, localised excavation and replacement.