For a flat roof to function correctly and to ensure the durability of its waterproof layers, it is essential to prevent the accumulation of ponding water and ensure that rainwater run-off falls are at the correct angle of slope. However the layers used to create these falls often impose an unnecessary additional load and bring no technical advantage.
As an alternative, Laterlite expanded clay based products can be used to create very lightweight, extremely strong, stable, durable insulating roof falls and screeds.
Ultra-lightweight concretes and lightweight closed-structure screeds (Latermix Cem Mini, Latermix Facile, Latermix Fast) can be used to create roof falls or thermal insulation, or screeds on which the waterproofing membrane or roof finish can be laid directly.
Ultra-lightweight pervious concretes (Latermix Cem Classic and Maxi) can be used for roof falls, or for thermal insulation or fill, including at deep thicknesses. The surface of the expanded clay should be levelled with a screed (made from Latermix Facile, Fast, or Massettomix Pronto) before applying the waterproofing membrane or laying the roof finish.
Expanded clay laid dry in granules (Laterlite and Laterlite Plus Expanded Clay), if necessary consolidated on its top surface with cement slurry, can be used as fill or to create run-off falls whilst providing excellent thermal insulation. They should be finished with a levelling and load distribution layer before applying the waterproofing membrane or laying the roof finish.
Expanded clay based products provide winter thermal insulation (U-value) because of their reduced conductivity ? (lambda).
Furthermore concretes, mortars and granulates based on expanded clay, being denser than traditional insulating materials, significantly increase the thermal mass and the thermal inertia of a roof and attenuate summer overheating in the spaces below (better thermal lag, temperature damping, and periodic thermal transmittance). This is particularly beneficial in the case of lightweight roofs of timber or steel construction.
Expanded clay can also be used in association with other insulating materials for complete high-performance technical solutions on warm roofs, inverted roofs, and any type of supporting slab (timber, steel decking, concrete, insulating panels, etc.);