Firestone makes Belgian school watertight

Holcim Building Envelope worked with Master Contractor MUTEC on the Les Trèfles building in Anderlecht, Brussels. Its UltraPly™ TPO thermoplastic polyolefin roof system effectively waterproofed the structure’s 7,000 m² roof.

Project ID

Anderlecht, Belgium


Green roofs

Project type

New build

Building type

Educational building


7,000 m²


Elevate UltraPly TPO 1.5 mm


Fully adhered

The stricking Les Trèfles building is a school and sports complex that has room for 750 pupils. The overall structure resembles a four-leaf clover (trèfle is French for ‘clover’). Brussels-based Árter Architects received an "Exemplary Building" (BatEx) prize for the design of this remarkable building, which is an innovative combination of passive construction, sustainability, learning and green features.

The client chose Elevate’s UltraPly™ TPO roofing system installed by Firestone Master Contractor MUTEC, who has a great deal of expertise and experience in TPO waterproofing and green roofs.

The 7000 m² roof surface was fitted with an adhered roof build-up consisting of a self-adhesive bitumen vapor barrier membrane, two layers of 15 cm-thick PIR insulation boards and a 1.5 mm thick Elevate UltraPly™ TPO single-ply membrane, fully adhered with contact adhesive. An eye-catching green roof was installed on top of it.

The choice of roofing membrane, as well as all other construction materials, was determined based on a Life Cycle Assessment (LCA), which takes into consideration the total environmental impact of products during their entire life cycle.