How many fixings are required to secure a flat roofing system?

The number of fixings required to secure a flat roof build-up varies by project. Fixings secure the flat roofing system against wind uplift, and the more a roof is exposed to wind, the greater the number of fixings required. Wind uplift calculations, carried out in accordance with EN 1991-1-4, determine the number of fixings required.

Calculations must be carried out prior to installing the roof system, and may be undertaken by the system manufacturer or a structural engineer. Project location and building height all play a part in determining the exposure of a particular building.

Where adhesive is being used rather than mechanical fixings, the same calculations establish the required application of adhesive to achieve sufficient attachment.

How does thermal insulation affect the fixing specification?

Thermal insulation may have a different fixing specification to the single ply membrane waterproofing, in which case the roof system specification needs to be designed accordingly. Different insulation types have different requirements for the positioning of fixings and the types of washer required.

Generally, fixings should be evenly distributed over the area of the insulation board, and not fixed at board joints.

A single ply membrane adhered to mechanically fixed insulation boards transfers additional load to the insulation fixings, and the number of fixings may need to be increased, subject to calculation.

IKO Polymeric offer a fixing calculation service for our single ply membrane roof systems. Please contact our technical services team or your local Business Manager to discuss your project.

For more information, please contact IKO Polymeric’s technical team.

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