Penetration

Penetration is a building-fabric opening or route where a service or fixing passes through a roof, wall, floor, ceiling, membrane, fire-separating element or other part of a property. In home energy work, the term can appear where PV cables and roof fixings, battery and EV charger cables, heat pump pipework, condensate drains, ducts, brackets or flues pass through the fabric of the building. It describes the physical opening or route that has to be designed, sealed or protected in the right context. It is not the same as planning permission, Building Regulations sign-off, structural suitability, roof waterproofing, fire stopping, airtightness, cable-entry hardware, DNO approval or MCS certification.