Derbyshire Aggregates
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Roofing Specifier – Applications

Flat Roof Ballast Chippings

Aggregates can be used to weigh down the insulation on inverted roof designs. By laying light coloured aggregates on the membrane, heat absorption is also controlled.

To provide a reasonable embedment and interlocking opaque surface, stone sized approximately 10mm-20mm are suitable. Low porosity materials prevent water absorption, which can result in frosted slippery surfaces. Larger cobbles 50-75mm can also provide an effective and visually attractive solution.

Flat roof aggregates are available in mini bags, bulks bags and loose loads.

Solar Reflective Chippings

Our specialized flat roof aggregates can help to protect flat roofing membranes from ultra-violet rays of the sun, which cause deterioration and provide a protective layer for light traffic.

Solar protection is often achieved by the application of white reflective chippings, usually limestone or polar white marble, not less than 12.5mm. The density of the stones will also slow the rate of heat gain and heat loss from the building.

The chippings can be laid loose or bonded in hot or cold bitumen compound to the roof covering.

Chippings can be used provide a ballast layer to help hold down the roof surface in exposed locations.

Inverted flat roofing aggregates

Inverted roofs are increasingly specified for new construction projects where flexibility of design and finish is required.

The principal thermal insulation material is applied on top of the weather proof covering so that the complete roof construction including roof covering is kept at warm temperatures during the winter months and at moderate temperatures during the summer months.

A 50mm depth of 20/40 aggregate may be sufficient to counter flotation of the insulation. Additional ballast May, however, be needed in those areas subject to wind uplift, such as exposed perimeters and corners.



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