plantex root barrier

How to Protect Waterproofing from Root Damage

Picture of Bryan Hindle CSRT CSSW GradIOSH

Bryan Hindle CSRT CSSW GradIOSH

Bryan is Technical Director of Brick-Tie Limited

Usually basement waterproofing needs no protection from tree roots; they’re outside the basement and not a threat to the contents.

However, green rooves are the exception because trees and shrubs may be encouraged to grow on top of the waterproof deck and then great care is needed if the waterproofing is going to last for more than a few growing seasons.

A contract we are working on in Cheshire has an indoor swimming pool and spa at basement level, which extends under a proposed landscaped garden with water features. We chose the proven Vandex range of concrete waterproofing products for the protection, above the suspended concrete deck. An Oldroyd green roof membrane with drainage was specified to finish.

Whilst the Vandex Super and Vandex BB75E waterproofing is very robust, it is good practice to protect the waterproofing from root damage. Green roofs have to be well drained and over time roots will invade every nook and cranny under the green roof membrane, in search of water and nutrients.

We specify and use Du Pont’s proven root barrier membrane, which is specifically designed and manufactured to resist root penetration. However, tough as the barrier is, there must be joints somewhere. The roots of some plants are very invasive and any poor detailing, joints or gaps will inevitably threaten the barriers integrity; it’s essential that any joints in the root barrier are correctly lapped and sealed. This is achieved using Oldroyd double sided butyl tape, applied in three strips and lap jointed. This not only seals the joints, but also provides a very secure joint, which cannot be split by the roots as they grow. Growing roots will stretch and pull the barrier and any weak joints will be found, so some diligence and skill is needed to get all of the root barrier joints just right.

Once the barrier is in place the Oldroyd Green drainage layers are added before top soil and planting takes place. This combination of Vandex super crystalline concrete waterproofing on the deck slab; Vandex BB75E on the screed, combined with an effective root barrier and Oldroyd green roof membrane, guarantees years of trouble free performance.

High quality waterproofing products are useless without high quality specification and skilled and well supervised application. Our surveyors hold CSSW (Certificated Surveyor in Structural Waterproofing), and our staff are dedicated and qualified.

Why not watch a demonstration of how the root barrier joints are correctly lapped and sealed, to protect the basement waterproofing products under the green roof.


We specialise in delivering robust basement waterproofing and green roof solutions – call 0800 591 541 for further information or to book a survey or an evaluation of a waterproofing design.

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