Stadium stand roof solar assessment at 27 metres, surveyed without roof access
Two steel monopitch stand roofs rising to 27 metres were assessed for a proposed solar PV installation. Both were cleared to carry the arrays as they stand, and the fragile roofs were surveyed entirely by drone with nobody working at height.
What the project needed.
A solar developer proposed PV across the stand roofs at a live football ground. Two separate questions had to be answered before design could progress: whether the existing steel frames could carry the additional load, and whether the roof coverings were in a condition to host the arrays. Those have different answers, and only the second one is settled by looking at the actual sheeting. The roofs are fragile, were never designed to be walked, and rise to around 27 metres, so the survey had to be done without putting anyone on them.
Work carried out
- Non-intrusive structural roof loading appraisal of both stand roofs
- Dead, imposed, wind and snow actions assessed to the Eurocodes
- Wind loading to BS EN 1991-1-4, snow loading to BS EN 1991-1-3
- Gravity and wind uplift justification of the proposed PV array
- Fixing uplift demand quantified to BRE Digest 489 (2014)
- Roof condition survey by 8K quadcopter drone, no personnel on the roof
- A separate documented verdict recorded for each stand roof
What charlton athletic fc, the valley actually involves.
The combined PV and snow load was calculated at 0.526 kN/m² against an allowable capacity of 0.90 kN/m². That margin is what allowed both stand roofs to be cleared in their existing condition, with no strengthening works required before installation.
Uplift governs more often than people expect on a stand roof. A monopitch at height changes the wind regime over the sheeting and its fixings, and a roof that carries the dead weight of an array without difficulty can still fail at its connections. Gravity and uplift were justified separately, with the fixing demand quantified rather than assumed.
Getting the condition answer without roof access was the practical problem. The coverings are fragile, and a live venue cannot easily absorb scaffolding or access equipment across two stands. An 8K quadcopter survey captured covering condition, gutters, flashings and historic repairs at a resolution good enough to inspect from, with nobody on the roof at any point.
Historic repairs were found across the roof and were inspected rather than noted and passed over. They were confirmed weathertight, which is what makes the condition verdict defensible afterwards. A survey that records a repair without reaching a view on it leaves the risk exactly where it started.
On site.
Both stand roofs were surveyed from the air by 8K drone, with the roof structure inspected internally from beneath.
Charlton Athletic FC, The Valley
Structural roof loading appraisal and roof condition report issued as separate documents, each carrying its own conclusion for each of the two stand roofs.
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