What is a window reveal?
A window reveal (Dutch: negge) is the visible surface between the outer face of a wall and the frame of a window or door. It is the “set-back” side of the wall opening — the narrow strip of wall you see when you look at a window from the side.
Why does a reveal exist?
Window frames are not always fitted flush with the outer face of the wall. They sit slightly recessed (for protection against rain and wind). This recessed position automatically creates a reveal on both sides of the opening.
- Outer reveal — the visible wall section outside, between the facade and the frame
- Inner reveal — the visible wall section inside, between the frame and the internal finish
Reveal depth
The reveal depth is the measurement of this surface — how far the frame is set back behind the facade. Standard in new build:
- Cavity wall with frame in the cavity: reveal ± 15 – 30 mm
- Solid wall: reveal ± 50 – 100 mm
Sealing the reveal
The junction between the reveal and the frame is a critical point for air- and watertightness:
- Expanded polystyrene or PU foam — thermal break, filling of gaps
- Sealant (EPDM or acrylic) — caulking along the frame edge
- Reveal board or reveal trim — a cover strip that neatly finishes the junction
Reveal block
A reveal block is a special masonry unit with an L-shaped profile, laid into the corner of the wall opening. It eliminates the laborious cutting of standard bricks and gives a neater joint at the frame.
Common mistakes
- Reveal not properly sealed — cold bridge and water ingress
- Frame set too far forward — rain drives directly against the window frame
- Unequal reveal left and right — window is not plumb in the opening
Related terms
- Window frame
- Reveal
- Window sill
- Cavity wall
- Facade
- Building Regulations