The waterproofing on this project was an external barrier system using bentonite mats. The project is a new, very large, cow barn built into a hill. The space required to waterproofing to Grade 1 per BS8102:2009.
The Grade 1 environment stipulates that no seepage is allowed; damp areas from internal and external sources are tolerable. This reduces the burden placed on the designers and allows for a much more cost effective solution to be implemented.
Midland Tanking was the designer and installer for the project.
Bentonite Waterproofing (external)
Type A – Barrier Protection
Preparation
The walls and steel posts were thoroughly cleaned and prepared for the bentonite waterproofing sheets. A perforated land drain was installed below the main barn slab. This reduces water pressure bearing on the walls and linked to a soak away. All joints within the walls were filled with a waterproof grout. The final preparation stage was to fill the steel posts joints. These joints were filled with a flexible, waterproof mastic.
Bentonite matting
External bentonite waterproofing is a method used to protect structures from water ingress by applying a layer of bentonite clay on the exterior surface. Bentonite, a natural clay with exceptional swelling properties when hydrated, forms a tight, impermeable barrier against water penetration. These sheets are particularly effective for foundation walls, tunnels, and other below-grade structures where preventing moisture ingress is critical.
Once applied, the bentonite membrane adheres to the substrate, creating a seamless shield that can withstand hydrostatic pressure and ensure long-term waterproofing protection.
To protect the bentonite membrane sheets, slip coats of 1200 gauge DPM were laid against the walls backfilling was carried out in stages and very carefully.
The waterproofing system was designed by Structural Surveyors in Structural Waterproofing (CSSW) in accordance with BS8102:2009.
All waterproofing materials were supplied by Triton Systems Ltd
