The MOHO concept has been developed by city living specialists Urban Splash and is the first ever private housing scheme in the UK where all 102 apartments have been constructed in a factory before being craned onto the six storey steel frame and fitted together on site. The scheme features a raised garden in a central courtyard, with lawns, mature trees, plants and pathways over a two-storey underground car park and storage area.
Icopal’s brief was to design a waterproof green roof package robust enough to accommodate a 45° slope sympathetic to the clients visual requirements – the garden is both an outlook from the apartment balconies and alternative access for residents. Durability, minimal maintenance and an insurance-backed 15 year warranty were also pre-requisites.
The system also had to incorporate a resin bound aggregate wearing surface to the pedestrian courtyard area which incorporated flush-fitting rooflights and a number of differing planting and drainage elements that made for an interesting design, including wheelchair ramps and an internal two-metre deep tree pit.
Icopal had already supplied its Sure-Weld TPO single-ply system for the upper roof when it was asked to look at the mid-level green roof. Icopal’s heavy duty elastomeric bituminous membrane system with built-in root inhibitors was the preferred solution, as it would provide a more robust design, particularly in the two-metre deep tree pit, than a single-ply system.
Icopal designed a system that was trialled at its factory in Manchester and over-seen by Urban Splash and ShedKM. Icopal was involved early on and worked through all the details with the architects. The design was very complex as there were a number of different materials and junctions which required lots of discussions and detail drawings to resolve.
The tree-pit, perimeter and internal planting troughs; areas of sedum, including areas around the entrance and circular stairwell; ramps, and detailing to a rear ventilation wall were waterproofed using the Total Torch and Rootbar systems. The green roof elements comprised drainage boards and filter layers, as well as the lightweight soil mix and extensive sedum substrate and sedum planting.
The project won the prestigious “Best In Show” accolade at the Flat Roofing Alliance (FRA) 2006 RBM Awards.