Installation

Insulation

RMAX ThermaRoof® comes in individually moulded boards of expanded polystyrene brand named ThermaRoof® as manufactured by RMAX.

The boards are 600mm x 1200mm with a shiplap on all four edges and drainage channels integrally moulded into the underside. Positive location lugs ensure the continuity of the drainage channels board to board.

• Depending on the density used R value per board is in the range of 1.25 to 2.00
• Densities are denoted by Class names  H, VH, X28, X32
• Compression strength at 10% deformation is in the range of 135 to 210 kPa depending on the density used.
  

After adhering the membrane to the roof deck, ThermaRoof® four sided shiplapped insulating panels are laid in one of the four Classes noted above.

Slip sheet

A water permeable, ultra-violet light and weather resistant material is required to prevent movement of the insulation by water and to minimise the ingress of fines from the stone ballast.

Ballast

River stones are recommended as suitable ballast to hold the insulation in place against the forces of wind and water, to prevent ultra-violet degradation of the insulation.

The stones should be smooth and free from dirt and grit and in the size range 15mm to 35mm. Most stones should be 20mm to 30mm size.

Ballast Weight

Ballast is required to secure the installation system from wind and potential buoyancy loadings. As wind loadings are stronger at edges and parapets perimeter ballast should be increased.

As an alternative, paving blocks may be used around the perimeter. They are also suitable for roof maintenance traffic.

Potential problems 'without' ThermaRoof® protection

Pictured below are two non-ThermaRoof® roofing installations. In these situations, a number of problems can occur:

• roof membranes are subject to daily temperature cycling, which prematurely ages the membrane and affects its ability to stop the penetration of water through to the concrete deck
• long term exposure of the roof membrane to Australia's particularly strong UV radiation may cause the membrane to become brittle and be more susceptible to fracture resulting from the stresses of thermal cycling or from mechanical damage. Building movement, impact damage and roof traffic are all sources of mechanical stress which can contribute to the failure of the roofing membrane.

In Installation A where the roof membrane is a concrete roof's only protection, then the roof itself is highly susceptible to damage.

The roof is subject to thermal cycling, with constant expansion and contraction. This has the potential to cause significant structural damage.

With insulation below the roof slab, the concrete deck acts as a sink/heat radiator, with higher air-conditioning operating costs and greater air-conditioning capital expenses (due to the requirement for larger units), when the building is constructed.

A larger number of control joints in the roof deck need to be built to facilitate expansion and contraction. As a consequence, a larger number of concrete pours also have to be made according to the number of control joints installed.

In Installation B, where the membrane is separated from the concrete deck by the insulation, the membrane is probably at greater risk, as it has been isolated from the buffering thermal mass of the concrete. In this circumstance the membrane has a wider daily temperature cycle than if no insulation had been used at all.

• in the Installation A, the roofing membrane is placed on the concrete deck with insulation below the deck.
  
  

• In the Installation B, insulation is first placed upon the roof deck, and the membrane is placed above.