Tender drawings for lightning protection are frequently more onerous than the standard requires. It is rarely deliberate. A designer working at an early stage, without a completed risk assessment or a confirmed structural build up, protects themselves by specifying a higher class, a tighter mesh, closer down conductor centres and a dedicated earth electrode at every position. The result is compliant. It is also, quite often, twice the material and a third more labour than the building actually needs.
Our approach is to price the compliant scope and price the drawing, and to show the client both. The compliant scope is what BS EN 62305-3 requires at the protection level established by the BS EN 62305-2 assessment. Anything the drawing asks for beyond that is listed as a separate, clearly described option with its own price. Nothing is hidden and nothing is quietly value engineered out behind the specification.
Three items account for most of the difference. The first is protection class. A drawing that specifies Level II where the assessment supports Level IV halves the mesh dimension and tightens down conductor spacing, and the copper follows. The second is natural components. A specification that instructs a dedicated external down conductor at every position, on a building with a continuous steel frame and piled foundations, ignores the cheapest and most durable conductor already in the building. The third is earthing. A dedicated rod, pit and lid at every down conductor position is a large cost when the foundation itself can serve as a Type B earth electrode.
Pricing this way requires evidence, not opinion. Where we propose to use a metal roof as air termination we continuity test it before accepting it. Where we propose to use the frame as a down conductor we confirm the connections and record the readings. Where the foundation is offered as the electrode we take resistance readings and issue them. If the evidence does not support the substitution, we install the dedicated component and say so.
It also requires the conversation to happen early. Once the concrete frame is poured and the connection points were not cast in, the natural component route is closed and the external system is the only option left. The most valuable half hour on any project is the one spent with the structural engineer before the frame goes up.
There is a commercial point behind the technical one. A contractor who prices only the drawing is competing on how thin they can cut their margin on work that may not be needed. A contractor who prices the standard is competing on knowing what is needed. The second conversation is more useful for everybody, and it produces a system that is easier to test and maintain for the next twenty years, because there is less of it and every part is there for a reason.
For clients the practical step is simple. Ask for the compliant scope and the specified scope as separate figures, and ask what evidence supports any natural component being used. A contractor who can answer both has read the building. One who cannot has read the drawing.