Devon Basement Waterproofing

Case Study / Waterproofing 

The Maples, Devon

Upgrading a basement to Grade 3: Habitable Environment

Devon Basement Waterproofing

MacLennan were approached by North Devon based Fearnley Lott Architects because their client has a pre-existing basement which was not being used, they wanted to replace this with a habitable basement and a replacement sunroom above. The new basement would have to be dug down with the side wall partially below the external ground level.

The family home is set high in the Torridge valley with stunning views over the River Torridge. They wanted to maximise the use of the space and be able to benefit from their surroundings. Fearnley Lott Architects requested MacLennan design a waterproofing solution.


The Maples, Devon


BS8102 states that 2 forms of waterproofing should be considered. This is not always necessary in an existing basement, but unless you are fully aware of the history of the basement it is always advised. As the original basement wasn’t a habitable environment, it was essential to have these 2 types of waterproofing installed.

The primary form of waterproofing (that will enable the issue of long-term guarantees) is achieved by the installation of a cavity drain waterproofing system. The 2nd form of waterproofing would be in the form of a cementitious tanking coating (Cemcoat).

The ventilated cavity drain system comprises of the membrane installed to walls and floors, a Hydrodrain channel around the wall floor join and wall mounted inspection ports, with insulation slab laid over on the floor. This particular system will have the drainage installed by others into a soakaway with a non-return valve, so there is no need to install a sump and pump.

On the deck area above the new basement, Polyprufe will be spray applied to ensure that there would be no leaks coming into the basement.


We have offered a fully guaranteed solution which is in line with the recommendations of BS8102/2022.

MacLennan take full liability for the waterproofing design which is covered by our £10 million PI cover. We also provide a 10 year insurance backed company guarantee, and offer a third party (GPI) insurance backed Guarantee.

All works were carried out by our fully qualified technicians and completed within the agreed time frames.


The Maples, Devon

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