The roof terrace of a RATP building begins a sustainable life with Foamglas®

This was to make it waterproof, impermeable to water vapor, to ensure incombustibility and to reinforce the insulation, because sensitive professional premises are located just under the roof. It was also necessary to guarantee good compressive strength without compaction. To meet these constraints, A.TEK project management, working for the SEDP delegated project management, prescribed FOAMGLAS® Ready Board type cellular glass insulation.

Once the existing insulating complex and waterproofing have been deposited, this cellular glass insulation is cold bonded to the steel tanks. Philippe Gourdon, Chargé d'Affaires SEDP, and Cédric Porquet, Chargé d'Affaires at Couvretoit, are very satisfied with the result and have agreed to share their testimony.

State of play

Philippe Gourdon explains the situation: “The Bourdon building, which dates from the 1960s, is a strategic location for the RATP. The space called "PCC room" became, at the end of the works, a workplace bringing together eight subway line command posts (lines 2, 6, 7, 7 bis, 8, 9, 10 and 11) . The people present 20 hours a day in this room mainly intervene in the event of an incident, accident or power cut on the lines. They are static in their seats in front of their screens. The room is heated by a heat pump providing hot air in winter and cooling the air during hot periods, the whole being managed by a thermostat and a BMS.

The place was completely renovated after a complete asbestos removal. This part of the building had six large skylights at the accessible roof. As part of the work and the new future of the room, it was decided to obstruct these skylights and to create two smoke extraction skylights bringing at the same time a weak and diffuse light, the room having no opening towards the 'outside.

The waterproofing of the roof, which was around twenty years old, was dilapidated. It was made up of a ribbed steel tank covered with an isorel-type concept, approximately 25 mm thick. The seal rested directly on the latter. Jean-Yves Moal of A.TEK specified for the renovation of this roof a new insulation system, composed of cellular glass plates, rigid and airtight, type FOAMGLAS® Ready Board T4 + cold bonded on the existing load-bearing element in a steel tank.

The FOAMGLAS® solution responds to the peculiarities of the structure

The FOAMGLAS® complex was installed by cold bonding directly on the existing steel tank. The old skylights were covered entirely with the same product after strengthening the hoppers, with the exception of the smoke skylights.

Cédric Porquet, who led the work, explains the specifics of the book: “Our company won this contract in 2015. The site included the renovation of approximately 800 m2 of an insulated, waterproof flat roof with a load-bearing element made of ribbed sheet steel. Among its particularities, it was necessary to replace a humidified insulating complex and a two-layer bituminous waterproofing by a compact complex and a new two-layer waterproofing, all with conservation of the existing steel tank. "

To meet these technical challenges, thermal insulation in bituminous FOAMGLAS® Board cellular glass was chosen: 14 mm thick panels (R = 3,4 m2K / W), non-deformable, insensitive to moisture, in which the air does not circulate, and whose thermal performance is guaranteed thirty years.

"Another particularity of this site, specifies Cédric Porquet, was to cold glue the foam glass insulation using bituminous glue, instead of the traditional bitumen heated in a pot for the bonding of cellular glass. We knew the rigidity and stability qualities of FOAMGLAS®. The lesson from this project was that with cold glue, cellular glass becomes very easy and practical to use. The installation of the pot, sometimes expensive on high terraces, and the heating time are saved. Our installation team really appreciated this new type of implementation. Welding the membrane in full adhesion to the surfacing bitumen of the new FOAMGLAS® Board sheets is practical, and if necessary, the insulating sheets can also be bonded together. This material is also useful for thermal insulation of vertical surveys. "

A perfectly insulated roof terrace

A well thought out and well managed site gives this RATP building the means to pursue its vocation in complete safety, bringing more comfort to its employees, without wasting energy, under a permanently insulated roof terrace. The thermal performances obtained gave full satisfaction to the customer:

"Cédric Porquet carried out with great skill all the work for this refurbishment of the roof and terrace," notes Philippe Gourdon. The temperature in the room is stable whatever the period. Last winter was not very rigorous to establish a real observation. On the other hand, during the summer, the room was tempered to 22 ° C inside, while the temperature recorded on the top of the terrace was much higher. This is a great proof of performance! "

• Client: RATP (75)
• Delegated contracting authority: SEDP (75)
• Project manager: A.TEK (94)
• Company: Couvretoit (75)
• Insulation used: FOAMGLAS® Ready Board T4 +