Inverted Roof Insulation

The inverted roof insulation protects the membrane from extremes of weather, such as frost, UV exposure and the expansion and contraction that comes about from summer/winter temperature cycles. The standard design consideration is that the rain falling on the roof filters through the ballast and between the insulation boards until it reaches the membrane, and then drains away through rainwater outlets. Such insulation is expected to be wet for the majority of its lifetime, and also one has to remember that some water is almost always trapped beneath the insulation boards by capillary action.

During a heavy rainfall, the membrane can become chilled by the water that filters through the ballast and insulation and then sits on top of the membrane, creates a risk that condensation could occur within the build-up of the roof.  In the majority of cases, any condensation that occurs will evaporate once the membrane has warmed up, with no accumulation of condensate. So, the waterproofing must be done on a quite dry surface, and also make sure than the waterproofing membrane doesn't have any cracks. The roof surface must have a correct slope carry the rainwater to draining outlets.

• Kingspan Styrozone N300R and Styrozone H350R Flat Roof XPS Boards are highly effective rigid insulation boards made from extruded polystyrene core covered with smooth skin on both sides. It is especially designed for protected membrane flat roofs and for green roofs as a popular alternative to traditional roofing systems, whereas its high comprehensive strength makes it ideal for inverted roofing.
• Cellecta Hexatherm XROOF 300L is an extruded polystyrene thermal insulation board designed specifically for inverted roof applications where a high resistance to compression and water absorption is essential. XROOF roof insulation boards are ideal for a multitude of roofing requirements, including pitch roofs, inverted flat roofs, flat roofs and green roofs.
• Cellecta Hexatherm XDRAiN is a high performance extruded polystyrene inverted thermal roof boards, featuring integrated drainage channels on their underside, which speeds up the shedding of rainwater from the roof, eliminating the need for a separating drainage mat, making them ideal for green roofs. Manufactured in accordance with BS EN 13374 and tested to BS EN 12267.
• Cellecta Hexatherm XMD is a high performance extruded polystyrene thermal insulation board bonded to a 6mm thermal laminate facing, suitable for vertical upstands. It combines the benefits of high performance extruded polystyrene with a facing board to produce a composite thermal board to suit a specific application. Manufactured in accordance with BS EN 13374 and tested to BS EN 12267.
• Sundolitt XPS300 is an extremely durable thermal insulation board made of extruded polystyrene offering exceptional thermal performance and versatility. It is a lightweight board that is able to withstand extreme loads. Sundolitt XPS300 is highly water resistance, so can be stored and installed in severe wet weather conditions with no deterioration during its life. It is easy to cut and customise on site and requires no special equipment or tools.
  

• Kingspan Aquazone is a high performance non-woven polyethylene membrane suitable for use on inverted roofs finished with gravel ballast, green roof systems and concrete pavers on appropriate supports. Kingspan Aquazone can can dramatically minimise the cooling effect associated with rainwater flowing down through the insulation and draining away. It can significantly reduce the insulation thicknesses required to achieve specified U–values.