The method of build chosen was pre-cast concrete Stepoc® blocks, infilled with reinforcing and concrete. This method does not usually lead to good placement of concrete so water can easily track through into the basement. Both this water movement and likely build up of limescale were the biggest challenges for the design team.

Project Details

New basement built from Stepoc blocks. Beautiful Basements were commissioned to build and waterproof the basement.

The basement is under a stunning family bungalow in beautiful rural Hertfordshire, effectively doubling the size of the property.

Once the excavation was complete and stabilised a blinding layer of concrete was laid and a ground water sump & huge foul sump were installed.

The slab was set out, reinforced and cast and first layer of stepoc block laid with mortar, ensuring the walls would be level. Each layer was then constructed, and reinforcing laid within to create the retaining walls.

Waterproofing Method

  1. Type A – Barrier protection. Externally, a permanently homogenous bitumen was sprayed onto the completed basement walls and was then covered by a drainage membrane and all linked to a perimeter drain, linked to a sump and pumping station
  2. Type C – Cavity Drainage System. Internally the walls were lined with a cavity membrane, all linked to underground drains and connected into a sump & pumping station


Waterproofing materials supplied by Delta Membranes and Koster Aquatecnic

Location: Hertfordshire
Completed: 2011