Nonsuch High School for Girls, Cheam
Remedial lightning protection works to a steel framed school building during re roofing, using the frame as the down conductor and strike plates fitted after tiling.
- Client
- Niblock
- Location
- Ewell Road, Cheam, Surrey SM3
- Sector
- Education
- Year
- 2020
5 m
Frame bond centres
2
Site visits
0
External down tapes
The challenge
A school building being re roofed in the summer holidays of 2020, with the lightning protection needing to be put right at the same time. The structure is steel framed, so the frame could form the down conductor network, but the roof was being tiled by another contractor. Our high level connections had to go in before the tiles and the finishing pieces after them, all inside a short holiday window and from the roofer's scaffold.
What we did
- Surveyed the building and prepared a RAMS for works starting 28 July 2020, with roof edge controls, mansafe and harness use, and COSHH controls for the solvent weld fixings and jointing compound.
- Used the steel frame as the down conductor system. Along the high points of the roof we drilled 10 mm holes in the steelwork at 5 m centres, fitted M10 bonding clamps and left 25 x 3 mm aluminium tape tails rolled up for the roofing contractor to bring out through the finished roof.
- Re attended once the roof was tiled and fitted a strike plate to each tail, giving a set of air termination points along the ridge connected straight to the frame.
- Bonded all exposed extraneous metalwork, including plant, flues, handrails and aerials, into the air termination network with purpose made M10 clamps.
- Completed the down conductor and earthing connections and tested the system on completion.
Outcome
A remedial system that brought the building back to a tested standard without external down tapes, using the existing frame and the re roofing programme to advantage. The system was tested and certificated.
Standards
- BS EN 62305-3
- BS EN 62561
- Protection
- Maintenance
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