Case Study · Commercial Structural Waterproofing
Type C Waterproofing for a Commercial Basement, Kvadrat Ltd, London N1
How we waterproofed a central London commercial basement for an international textile brand, designed to BS 8102:2022 and built to be maintained for the long term.
Written by Sam Fitzgerald, Founder & Surveyor
Kvadrat Ltd (textiles)
Shepherdess Walk, London N1
Commercial basement
Type C cavity drain membrane
BS 8102:2022
10-year written
The Brief
Kvadrat is an internationally recognised textile and fabric brand, and their central London premises included a below-ground space they needed as dry, usable commercial floor area. For a business like this, a damp basement is not a cosmetic problem, it is a direct risk to stock, equipment and day-to-day operations.
They needed a system that would keep the space reliably dry for the long term, meet British Standards for the building, and be installed with minimal disruption to a live, working commercial site.
The Challenge
Like most below-ground spaces in London, the basement was exposed to groundwater pressure through the walls and floor. The brief carried several non-negotiables:
Our Waterproofing Solution
After assessing the structure, we designed and installed a Type C cavity drain membrane system, widely recognised as the most reliable method for an existing basement because it manages and controls water rather than trying to block it, directing any groundwater safely to a pumped drainage system.
Cavity drain membrane
High-performance membranes were fixed across the basement walls and floors, creating an air gap that lets any water entering the structure drain safely behind the system, away from the internal finishes.
Perimeter drainage channel
A drainage channel around the base of the basement collects the water held behind the membrane and directs it to the sump chamber.
Sump chamber and pump system
A sump and pump system actively removes the collected groundwater, automatically and continuously, with the capacity to cope during heavy rainfall or rising groundwater. The pump is the critical component that keeps the whole system protecting the space around the clock.
Built to British Standard
The whole system was designed and installed in accordance with BS 8102:2022, the recognised UK standard for protecting below-ground structures against water ingress, covering the system design, the membrane installation, the pump and drainage design, and long-term serviceability and maintenance access.
The Outcome
The basement is now a dry, protected environment fit for commercial use, with long-term protection against groundwater and a system designed to be maintained over its life. The works were completed with minimal disruption to the occupier and handed over with our written 10-year guarantee.
Why It Matters
For commercial premises, the choice of waterproofing type is a business decision as much as a technical one. We specified a Type C system precisely because it is maintainable: if anything ever needs attention, the drainage and pump can be serviced without ripping out the basement and halting the business. For a tenant whose operations and stock depend on a dry space, that serviceability, alongside full BS 8102:2022 compliance, is what protects the investment for years, not just on the day of handover. It is the same approach we bring to all of our commercial waterproofing and structural waterproofing work.
Managing a Commercial Basement?
We design and install commercial waterproofing to BS 8102:2022. This kind of project is the right fit if you have:
Start with a waterproofing survey and we will design the right system for the structure and how the space is used.
Frequently Asked Questions
How long does a Type C cavity drain system last?
A correctly designed and installed system can last for decades, and because the drainage and pump are maintainable, it can be serviced over its life rather than ripped out and replaced.
Why choose Type C over tanking for a commercial basement?
Type C manages water rather than relying on a sealed barrier, and it stays maintainable, so it can be serviced without disrupting the business. For a commercial space, that serviceability and reliability under groundwater pressure usually make it the safer long-term choice.
Does a commercial waterproofing system need maintenance?
Yes, minimal but important. The sump, pump and drainage channels should remain accessible and be checked periodically. We design every system with that maintenance access built in.
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Protecting a commercial basement?
Talk to our specialist team about a Type C system designed and installed to BS 8102:2022, built to be maintained for the long term.
Sam Fitzgerald is the founder of Advanced Damp and a working damp and structural waterproofing surveyor with over 12 years of experience diagnosing and treating moisture problems in residential and commercial properties across London and the South East. He is FODCS certified (a Federation of Damp Certified Surveyor) and a member of the Federation of Damp. His hands-on work covers rising damp, penetrating damp, condensation, basement waterproofing to BS 8102, and thermal imaging surveys, and he has personally completed over 400 damp surveys across properties of every type and age. Everything he writes draws directly from jobs he has carried out. He does not write about treatments, products or causes he has not dealt with first-hand in the field.
