Ilona Rose House

Ilona Rose House, London

A structural waterproofing solution was required for the four-storey basement area of this 80,000 sq. Grade II listed office space, in the heart of Soho.

The Challenge

Ilona Rose House consists of two new office buildings for Soho Estates. The main building provides 25,000sqm of office space with a smaller annex building alongside, together providing new shops, restaurants, along with pedestrian walkways and roof terraces.

These two buildings sit on a communal basement which is four-storeys deep. One quarter of the basement is naturally lit and includes a double height, tiered, 60-seat sound editing theatre.

Cast Contacting Ltd were contracted for the design, supply, and Installation of the basement waterproofing.

Ilona Rose House

The Solution

Working jointing with Sika® Waterproofing, our specialist design team proposed the BBA Approved Sika® CD 8mm Cavity Drain system, feeding into a twin sump pumped solution with battery back-up, meeting the requirements of BS 8102:2022 Sikalastic® 1K Cementitious waterproof coating was applied to the inside face of the concrete channels, at wall/floor junctions and behind the suspended concrete slab.

The drainage channel was installed with jetting eyes to allow for future maintenance of the system.
Sika® Cavity Drain Sealing Rope and Corner Seal Tape were also applied, sealing around the outside of all existing conduits.
The entire system was covered by Cast Contracting’s £10 million Professional Indemnity insurance, and our 10 Year Installation Guarantee.

Client Testimonial

“We were very impressed with the attention to detail and overall workmanship we received from Cast
Contracting Ltd.
This project presented us with a particularly complex and challenging environment, which is subject to
constant water ingress. The Cavity Drain System installed by CCL has consistently proven its worth by
keeping the basement clean and dry.”

Colm Henry
Contracts Manager – Realtime Civil Engineering Ltd

Ilona Rose House

Products Specified

  • Sika® CD Anti Lime Coating
  • Sika® CD 8mm Cavity DrainSikalastic®
  • 1K Membrane
  • Sika® CD Drainage Channel

Design | Supply | Installation

Cast Contracting Ltd (CCL) is the UK’s leading specialist in Design and Installation of all Waterproofing, Tanking and Ground Gas Systems across the United Kingdom. CCL prides itself on offering the highest level of service throughout the Design, Planning, and Installation process.

Structural Waterproofing & Ground Gas Solutions

CCL’s in-house design team can offer a comprehensive proposal for all scenarios in line with BS:8102 and BS:8485.

CCL Guarantees

One of the most comprehensive Guarantees across the industry, taking full project ownership.


Cast Contracting Limited is one of the longest standing industry specialists. As it is now part of the CCL Group of Companies, Cast Contracting Ltd has the additional stability and support with over sixty employees across the Group.

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