Roof Insulation

Upside down roof concept

The upside-down roof concept is as simple to use as it is effective. As you see in the following pictures. The efficiency of the upside-down roof concept has been proved extensive tests and practical application over long years in Europe, Canada, USA and the Middle East.

Advantages of the Upside down roof concept

  • Simplicity of the application of this concept
  • Efficiency which is proven in most of world countries
  • The waterproofing membrane is protected from extreme thermal stresses, high ultraviolet exposure and from mechanical stresses occurring during construction and subsequent use.
  • The life expectancy of the waterproofing membrane is substantially increased.
  • Maintenance costs are significantly reduced.
  • Roofing membrane reduces temperature variation, in the upside-down-roof.


Polyfoam panels can be worked with conventional wood working tools. The panels could be bound together with hot bitumen, dispersion-type structural or special adhesives. Instruction for use and safety precautions relating to the adhesive must be observed.

Water proofing Membrane

Ensure the concrete slab is clean and fairy smoother, then membrane can laid directly on the slab. If the concrete surface cannot be made smooth, it is required to laid directly on the slab. If the concrete surface cannot be made smooth, it is required to lay a protection sheet below the membrane.

Protection Layer

Protection layer against the wind uplift, buoyancy and ultraviolet degradation can either be of gravel or paving slabs. When using pebble gravel it is necessary to use the round, washed type having a 15-30mm size distribution, laid dry on a synthetic, on fabric, rot proof felt filtering layer. To determine the quality of the pebble gravel paving slabs to be laid, it is advisable to adopt the values indicated in the following table.


With the normal gravel-topped specification, water percolates down through the gravel over and between the insulation boards, until it reaches the water proofing membrane where it then drains off to the roof outlets. On Terrance decks, water will drain from the top surface of the terrace and Polyfoam and from the roof membrane.

The draining outlet should, therefore have a connection at the membrane level and at the top terrace and polyfoam top surface levels. The roof slab should be sloped towards the drainage outlet. Waterproofing membrane should be properly installed around the drainage openings so that water drains off the waterproofing membrane to the roof outlet.