Harmer SML Cast Iron Drainage from Alumasc Water Management Solutions (AWMS), has been specified for the redevelopment of Pegasus House, a landmark scheme in London's Mayfair.
Pegasus House has undergone a major transformation to create premium mixed-use space occupying a prominent corner position at Piccadilly and Sackville Street. The redevelopment was delivered by McLaren Construction, and also incorporates the sensitive restoration of the neighbouring Grade II listed Nuffield House, combining contemporary construction with the preservation of the area's historic character.
Delivering a scheme of this scale in one of London's most prestigious locations required careful coordination across every element of the build, including the concealed building services infrastructure that will support its daily operations.
Built for Demanding Environments
Effective drainage is fundamental to the performance of any commercial building, with underground and basement environments presenting additional challenges. For Pegasus House the project specification required a number of key considerations, the priorities being reliability and longevity. Cast iron drainage has a well-established reputation for delivering decades of dependable service, making it an ideal choice for premium developments where whole-life performance is critical.
Installed throughout the building's underground service areas by Tower Mechanical Services, Harmer SML Cast Iron provided a solution ideally suited to challenging conditions, offering the durability needed to minimise disruption from future maintenance. The system uses mechanically jointed connections, including Teekay Axilock-S High Pressure couplings, which provide axial restraint of up to 10 bar and are particularly suited to areas where pressure is highest or additional protection is required, such as basements and the base of stacks.
Teekay Axilock couplings incorporate grip rings at each end to securely lock plain-end pipes together under pressure, and a fully rubber-lined construction to provide high levels of corrosion resistance. The system also eliminates the need for hot works, flanging, welding, pipe grooving or threading, allowing Tower Mechanical Services to work efficiently within the constraints of the basement service areas, with no compromise on installation quality.
Harnessing the Inherent Qualities of Cast Iron
Manufactured from robust cast iron and tested in accordance with BS EN 877, Kitemark certification and CE Mark conformity, Harmer SML offers exceptional mechanical strength and impact resistance alongside the highest A1 rating for product reaction to fire, in accordance with BS EN 13501-1.
Technical Approvals Marketing Approvals
Initials Date revised (if applicable) Date approved Initials Date revised (if applicable) Date approved
SF 19.08.26 08.09.26
WW 08.09.26 08.09.26
The Pegasus House development comprises office, retail and residential space, so the inherent acoustic benefits of Harmer SML were also an advantage. Unlike lighter pipework materials, cast iron naturally dampens the sound of flowing wastewater, helping to reduce noise transmission through the drainage system and contributing to a quieter, more comfortable internal environment.
As a non-combustible material, cast iron maintains its structural integrity when exposed to high temperatures and does not contribute to the fire load of the building.
Additionally, the Harmer system also aligned with the project's sustainability ambitions. Cast iron is manufactured using recycled content and is itself fully recyclable at the end of its operational life. Combined with its exceptional durability, this makes it a sustainable option for demanding public developments designed with longevity in mind. Harmer Building Drainage sits under the AWMS umbrella as one of five brands well known for innovation, quality and longevity. The four accompanying brands are Alumasc Rainwater Gutters & Downpipes; Skyline Architectural Aluminium; Wade Building Drainage and Gatic Civil Drainage & Access Covers.
