Raking light
Low-angle light parallel to a wall or ceiling, exposing joint bands and surface defects. Used to inspect Level 4 vs Level 5 plasterboard finish.
Ask Chalkline about this →Raking light is low-angle light striking a wall or ceiling almost parallel to the surface, exposing joint bands, fastener pops, and surface unevenness that direct front-light hides. The most common sources on a finished house are afternoon sun through windows, downlights close to a wall, and pendant lights past a ceiling joint.
Raking light is the standard inspection method for plasterboard finish disputes at PCI. A surface that looks flat under direct overhead light can show clear joint banding under raking light. The difference between AS/NZS 2589 Level 4 and Level 5 finishes is largely a question of whether the surface tolerates raking light.
Specify the inspection method in the contract: “raking-light inspection at AS/NZS 2589:2017 viewing distance” prevents most arguments. Without it, “joints visible from 100mm under a torch” gets bundled with “joints visible across the room from window light” and the dispute drags.
Also known as: Glancing light, critical light.
Category: Quality & inspection.