Minimal Intervention
The conservation principle of doing as much as necessary but as little as possible — prioritising stabilisation over restoration, and original fabric over replacement.
Minimal intervention is the conservation principle that the smallest amount of physical intervention sufficient to achieve the conservation purpose is the right amount. It favours stabilisation of existing fabric over restoration; repair over replacement; consolidation over reconstruction.
The principle is grounded in the recognition that every physical intervention on a historic building carries risk of damage to original material and loss of authenticity. The uncertainty of the outcome of an intervention is always present; therefore, the more intervention, the more cumulative risk.
In practice, minimal intervention requires conservation practitioners to establish clearly what the intervention is trying to achieve, and then choose the method that achieves that goal with the least disturbance to existing fabric. It does not mean doing nothing — sometimes substantial work is required to stabilise a structure — but it means doing no more than is necessary.