Active roofs: two expert Foamglas solutions insulate the parking lot of the Allonzier-la-Caille Medical Center (74)

Intended for parking areas, the FOAMGLAS® system under asphalt provides a quick and simple solution in terms of execution. Its incompressibility and its tightness make the structure reliable as well as its operation.

This is the solution that was chosen for the car park at the medical center in Allonzier-la-Caille (Haute-Savoie), located above a supermarket. The roof of the car park is made up of an insulating complex + waterproofing + protection and wearing course made up solely of asphalt, resting on a load-bearing element in concrete slab. This complex incorporates FOAMGLAS® cellular glass insulation of unfailing reliability. The FOAMGLAS® READY F thermal insulation is associated with a two-layer waterproofing and two layers of asphalt (10 cm thick in total). Providing access to the street, the car park access ramp has a 5% slope. This slope was made in the insulating layer with FOAMGLAS® READY TAPERED F 5%.

Overcoming the constraints of economy and planning was a successful challenge for the team that designed and built the work - the AJ architecture agency (13), the project management AQCIOM (42) and the TISSOT company Sealing (73).

A car park insulated with cellular glass, sealed and protected by 2 layers of asphalt

Three mastered objectives

The choice of FOAMGLAS® thermal insulation for the car park roof met the following 3 objectives, defined by a preliminary study:

• Provide an economical solution,
• Ensure speed of execution,
• Minimize the risk of water infiltration to almost zero by integrating a reflection on the risk analysis. Water damage in a supermarket not being possible

The chosen solution includes:

• A vapor barrier (mountain climate),
• FOAMGLAS® READY F thermal insulation,
• Reinforced two-layer waterproofing,
• A protection and surface layer made up of two 5 cm asphalt layers.

The Specifications for this “FOAMGLAS® Asphalt” solution has been validated by SOCOTEC.

• An economical solution: 10 cm of asphalt form the protection and rolling layer. This is possible thanks to the exceptional rigidity of FOAMGLAS® READY F. This insulating + waterproofing + protection complex is the thinnest and lightest of all the existing flat roof solutions accessible to light vehicles. This system makes it possible to do away with the traditional concrete protection slab and the drainage located below. The asphalt plays a triple role: protective layer, surface layer and finishing layer. FOAMGLAS® READY F thus contributes to reducing the permanent loads, and to reducing the altimetry of the finished levels of the surface of the car park, parapets and thresholds.
• A quick solution in the execution phase. One of the advantages of the asphalt in such a configuration lies in the fact that the waiting time before exploitation, after the implementation of the asphalt, is much shorter than in the case of a concrete slab of protection (long drying time). After laying the first layer and the second the next day, the cars can be driven from the third day!
• Reduce the risk of infiltration to almost zero in order to avoid any leaks in the supermarket. FOAMGLAS® cellular glass, 100% waterproof and moisture-proof insulation, has zero permeability to water vapor (EN 12086). Its water absorption by immersion is also zero (EN 1609 and 12087). Exceptional physical characteristics for thermal insulation.

The joints between the insulating plates are also sealed. They are made of bitumen over the entire height of the plates. Indeed, the low coefficient of expansion of FOAMGLAS® allows this installation technology: the bonding of the insulating sheets together over the entire surface of the roofs. This is an exclusive solution offered by Owens Corning.

The insulating layer made of FOAMGLAS® cellular glass is thus sealed in the mass. Analysis of the first risk: if, by accident, rainwater infiltrates under the waterproofing membrane, it cannot enter the cellular glass. Analysis of the second risk, very unlikely: if, at the same place as the accident on the waterproofing, there is a FOAMGLAS® joint and it has been badly glued, water could enter the insulating layer. However, it will be blocked by the special "mountain climate" vapor barrier and will not be able to migrate into the insulating layer, which is waterproof. Analysis of the third risk, of a tiny probability: if, also in the same place, the vapor barrier is faulty, the water will then pass into the slab, but the leak will be located and easily spotted by cutting the asphalt, waterproofing and insulation and re-gluing of insulation, waterproofing and installation of a new asphalt (easy repair that the concrete slab protection solution does not allow).

FOAMGLAS® READY TAPERED F 5% insulates and creates the slope of the car park access ramp from the road

The compressive strength of FOAMGLAS® F is very high (Rc= 1 kPa - EN 600) and is guaranteed over time. Another unique characteristic for a thermal insulator: the settlement of FOAMGLAS® READY TAPERED F is independent of its thickness: cellular glass is incompressible up to its limit value and its settlement is always less than 826 mm. These exceptional data prompted the project manager to innovate and create the slope of the car park access ramp with FOAMGLAS® READY TAPERED F with an integrated slope of 5%, instead of a conventional concrete form.