Roof loading appraisal across an 85 metre leisure centre roof

Roof 1 is a duo pitch, 35.5 metres span by 85.5 metres long, with eaves at 9.26 and 8.56 metres and purlins at 1.4 metre centres on a 7.5 metre bay spacing. Roof 2 is flat, 22 by 58 metres, with eaves at 8.4 metres. Each was taken on its own geometry rather than averaged into one assessment.

Dead load was built up from the actual specified roof make up rather than a default allowance: 0.12 kN/m² for the trapezoidal sheet, 0.15 kN/m² for the metal purlins and 0.15 kN/m² for services, giving 0.42 kN/m². The single ply covered area was taken separately at 0.45 kN/m². Imposed roof load was 0.60 kN/m² to BS 6399 Part 3 and Eurocode 1.

Wind was calculated on a site specific basis rather than from a regional figure. Basic wind velocity was taken as 21.8 m/s from the BS EN 1991-1-4 wind map, with the site at 66.1 metres elevation, 55.32 km from the sea and in town terrain. Both positive and negative internal pressure were run, with wind acting perpendicular and parallel to the front elevation.

The conclusion was that the roofs and their supporting framework can carry the anticipated loading from the proposed installation. Panel fixings were explicitly left outside the scope and flagged as a design by others, because the fixing into a given covering is a different question from whether the frame beneath it has the capacity, and quietly implying otherwise is how gaps open up between consultants.