DESIGNING A FOAMGLAS® COMPACT ROOF
Find out how simple it is to design and execute an activity Roof with FOAMGLAS® Compact Roof.
How to design a compact roof correctly
The design of a FOAMGLAS® Compact Roof is always the same: a load-bearing construction combined with FOAMGLAS® insulation and a impermeable system, fully-bonded and adhered by bitumen over the entire surface. Depending on the size and conditions of the project and your experience you can choose either hot bitumen or cold bituminous based adhesives. Or you can combine them both successfully.
Using hot bitumen as an adhesive
Hot bitumen is the oldest but still the most commonly used technology today. Bitumen is heated to a temperature of 200°C and used to bond naked FOAMGLAS® slabs to the substrate for rapid, high quality compact bonding. Hot bitumen is also recommended to bond the first bituminous membrane to the top surface of the FOAMGLAS® insulation slabs.
Bitumen is heated to a temperature of
and used to bond naked FOAMGLAS® slabs
Note that the use of hot bitumen may be prohibited for safety reasons or considered inappropriate in small, cramped areas and large roof slopes.
Using cold adhesives
For all of those times when hot bitumen is not an option, Owens Corning FOAMGLAS® has developed a range of compact roof systems using cold adhesives. In our portfolio, there are several adhesives that can be used depending on the substrate and the gradient of the bonded surface. FOAMGLAS® insulation slabs are then bonded to the supporting structure and to each other using the right cold adhesive.
FOAMGLAS® Compact Roof construction formula: load-bearing construction + FOAMGLAS® insulation + impermeable system, fully-bonded and adhered by bitumen over the entire surface.
Depending on the situation, there are two possibilities
- The first is to use naked FOAMGLAS® slabs glued with cold bitumen adhesive and adhere the first bituminous membrane with cold adhesive.
- The second, more frequent approach is the use of FOAMGLAS® READY slabs with a thin layer of asphalt pre-applied on the upper surface. The first bituminous membrane can then be fully torched on FOAMGLAS® material. Depending on the technology of application of the bituminous membrane, you will then need to select the right type of separation layer on the reverse side: for flame torching it is possible to use a separating layer of burn-off PE foil; for bonding to adhesives separation sandblasting is more suitable. The main modified bituminous membrane is then no longer glued to the compact build-up but torched over the entire surface by flame, typical for this membrane type.
FOAMGLAS® COMPACT ROOF PROPERTIES
Vapour tight
The bonding of FOAMGLAS® vapour tight slabs with hot bitumen or bituminous based cold glues on the substrate and in the joints results in a homogeneous thermal insulation layer, making it vapour tight throughout its thickness and across the entire surface. In the FOAMGLAS® Compact Roof build-up, no interstitial condensation of water vapour can occur, regardless of the humidity or direction of diffusion.
Impermeable
In a FOAMGLAS® Compact Roof system, the impermeable layer and the insulation are fully and perfectly adhered to each other and to the supporting layers. FOAMGLAS® insulation does not absorb moisture and is both impermeable and water vapour tight. This build-up ensures that moisture cannot migrate above, below, between or inside the thermal insulation slabs. With these properties, FOAMGLAS® insulation provides additional security as an additional impermeable layer in the overall build-up.
High compressive strength, zero deformation
The bitumen layer on FOAMGLAS® bearing surfaces ensures a perfect load transfer between the impermeable layer, thermal insulation and construction. A thin layer of bitumen fills the surface cells of the cellular glass, increasing the compressive strength and adhesion of the roof build-up to the bearing structure without any deformation. Try it out for yourself: simply take a few steps on the rigid FOAMGLAS® Compact Roof and be convinced that it feels as if the impermeable layer is applied directly to the concrete substrate, making it an ideal base layer for activity roofs.
Fire safety first
FOAMGLAS® insulation slabs are, by nature, non-combustible and classified in the reaction to fire class A1. In the event of a fire, no smoke, toxic fumes or airtightness can occur, because the insulation slabs are impermeable to air. And without oxygen, even the bitumen adhesive cannot burn. Compared to mineral fibre insulations, the FOAMGLAS® compact build-up significantly slows the spread of flames, nor does it contribute to the fire spread.
Time-tested thermal insulation
FOAMGLAS® cellular glass insulation was first produced in Europe in 1965, being put to use shortly after. In 2016, the German Institute FIW Munich (Research Institute for Thermal Protection) took samples of FOAMGLAS® slabs from roofs constructed between 1973 and 1989 and tested them thoroughly. The test results showed that after nearly half a century, the insulation properties and compressive strength had not deteriorated. FOAMGLAS® insulation stands the test of time.
Durable
FOAMGLAS® insulation is free from environmentally damaging flame retardants, propellants, or eco‑toxic components. Designed for lifetime durability, it maintains its insulation performance and structural integrity over generations of use. At the end of its service life, FOAMGLAS® slabs can be recycled as landscaping filler or insulating granulate, supporting circular and responsible material reuse.
