Corrugated fibre cement or sandwich panels? Comparing complete roof systems

Label the layers on a section drawing for each proposal. A photograph shows the exposed surface. The section shows which functions the product already provides and where the contractor must install further layers.

An unheated store that needs shelter from rain has different requirements from a hall with controlled temperature and humidity. Asbestos-free fibre cement may provide the covering in either case. For the conditioned space, include insulation and internal layers in the comparison. Steam from production and frequent washing introduce further demands. Omitting a layer that the process requires changes the scope of the quotation.

Check support spacing, fixings and the structural behaviour of each roof. Changing the covering may change the dead load and invalidate previous assumptions. Do not assume fibre-cement sheets provide lateral restraint to purlins or act as a diaphragm. For sandwich panels, establish what the specific product and fixing arrangement can carry. Include laps, accessories and environmental loads so the designer can approve the supports and connections for the exact assembly.

Record internal temperatures, sources of moisture and ventilation arrangements. Fibre cement can temporarily buffer some moisture. Ventilation and, in an insulated roof, correctly designed layers still govern what happens to that moisture. A sandwich-panel roof also relies on sealed joints and carefully detailed penetrations. Assess both assemblies for air and vapour movement before accepting a claim about condensation.

A sheet’s reaction-to-fire classification and the fire resistance of a complete roof describe different properties. Match the tested assembly, including its structure and insulation, to the proposed roof. Rain noise and sound insulation also depend on the build-up. Compare tests on equivalent assemblies and use the designer’s assessment where requirements affect staff or neighbouring buildings.

Prefabricated sandwich panels deliver several layers in one lift. They still need suitable transport, lifting and installation arrangements. Corrugated sheets with separate layers require a different sequence. Price the preparatory work and consider height, access, weather, penetrations and phasing. Check what milestone each bidder calls completion, particularly whether the building can be used once the quoted work is finished.

Allow for materials, accessories, structure, labour, transport and future service access. Price fibre-cement sheets by their effective cover and panels by the cut layout and joints required. Consider how a damaged element would be replaced and where future equipment will go. The better fit depends on which assembly meets the building’s actual needs over the period you are costing.

Compare two complete roof sections under the same operating conditions. Check structure, moisture, fire performance, installation and readiness for use in both quotations.