How to build?
No compromises
How to build

When it comes to the roof of a building, no compromises should be made. A roof is meant to give you complete peace of mind throughout the lifetime of the building. Possible problems that you may encounter can be easily prevented by working with the right materials and total build-up to ensure qualitative performance over time.

If activity roofs is the question,
FOAMGLAS® Compact roof is the answer

What is a compact roof?

While the application may differ depending on the level and the type of Activity Roof, the basic build-up is always the same.

FOAMGLAS® Compact Roof is a simple, robust and versatile roof build-up with the exceptional properties of FOAMGLAS® thermal insulation.

The compact build-up consists of 3 basic layers glued together fully bonded and joints closed by bitumen or cold adhesives:

  • a bearing structure
  • FOAMGLAS® cellular glass
  • a waterproofing layer

This technically perfect roof system is easy to construct and removes all risks associated with activity roofs. Depending on the size and conditions of the project –as well as your experience and preference –you can choose either hot bitumen bonding or working with cold adhesives. Or you can combine them both successfully.

The fully bonded joints ensure that the roof surface is completely watertight and compartmented.

FOAMGLAS® Compact Roof helps you protect what matters most

FOAMGLAS® cellular glass insulation is a lightweight, durable and rigid insulation material made up of millions of hermetically sealed glass cells.

This gives it exceptional protective properties such as incombustibility, superior compressive strength, guaranteed water and vapour tightness and long-lasting thermal insulation performance.

Our FOAMGLAS®Compact Roof build-up provides ultimate protection. 

Read on to find out how we help you protect what matters most.

100% Vapour tight

The bonding of FOAMGLAS® vapour tight slabs with hot bitumen or 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.

100% waterproof

In a FOAMGLAS® Compact Roof system, the waterproofing 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 waterproof and 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 extra security as an additional waterproofing 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 waterproofing, 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 waterproofing is applied directly to the concrete substrate, making it an ideal base layer for activity roofs.

Incombustibility and fire safety

FOAMGLAS® offers more than lifelong thermal performance. The insulation material plays a crucial role in the fire safety of the building. Cellular glass insulation offers total peace of mind: it is inflammable and does not contribute to the spread of fire. It also does not release smoke or toxic gases, and produces no flaming droplets that can cause injury or damage the building. 

Long lasting thermal performance

At FOAMGLAS®, we stand behind the quality of our insulation solutions. Third-party testing has proven that the thermal conductivity and compressive strength of FOAMGLAS® insulation do not substantially deteriorate over time.

100 year service life

Our EPDs confirm a time-tested performance, as it states a reference service life of 100 years*! This can make all the difference as building, designing and utilising an Activity Roof is not without risks.

At FOAMGLAS we believe things should be built to last. Building for life is about reducing both impact and waste for future generations. It is our duty.

* Stated in EPD-PCE-20200300-IBB1-EN, published by Institut Bauen und Umwelt e.V. (IBU)


The benefits can’t be denied: FOAMGLAS® Compact Roofs offer you total peace of mind and flexibility. You can invest in an Activity Roof at any time throughout the lifetime of the building, depending on your budget and needs. As your needs change over time, you can easily adapt the function of your roof accordingly.  

How to install a FOAMGLAS® Compact Roof

Seeing is learning. We have created four free video tutorials that demonstrate how to install a Compact Roof build-up on a concrete or metal roof structure using the bitumen coating method or the pour and roll method.

Compact roof system on reinforced concrete deck. Bitumen coating method
Compact roof system on reinforced concrete deck. Pour and roll method
Compact roof system on steel deck. Bitumen coating method
Compact roof system on steel deck. Pour and roll method

Want to learn more about activity roofs?

Discover all insights of Activity roofs

In the document "Safe, long-term solutions for activity roofs", we address the many issues that designers face and that can lead to serious consequences if not anticipated.
Then we describe new solutions adapted to the uses of active roofs (photovoltaic, vegetated, accessible to pedestrians/vehicles).

Our document will provide you with the keys to designing and making a success of these living spaces, with total architectural freedom.