Light Reading: Wall Washing vs. Wall Grazing

Wall wash and wall graze. Lighting technique terms you may have heard before, but what do they mean and when do you use them? Illuminating a wall adds a visual impact to the space, and is typically done in either of these two main ways. You must couple the wall lighting method with the correct type of wall (smooth or textured) to get the desired effect. Continue reading to compare these two techniques:

Wall Wash

Wall wash is when the entire surface from top to bottom uniformly lit in a smooth graded wash, which hides any imperfections by eliminating their shadows. Wall washing is a technique commonly used for smooth walls because the lighting will hide any blemishes and make the surface appear to be perfect. To achieve this effect, the luminaire is usually a minimum of 12 inches away from the wall, so the beam angle can cover more surface. The fixtures also need to be mounted at or above ceiling height, so they can effectively cover the whole surface. This visually pleasant effect provides ambiance and can make spaces feel larger and brighter.

Wall Grazing

Grazing a wall has a completely different effect, and as the name implies, light “grazes” and skims the wall surface by having the luminaire mounted less than 12 inches away from the surface. This shift in beam angle will now accentuate textures and special architectural elements on the surface for a dramatic punch. So when using materials such as brick or wood, wall grazing really brings out the natural texture of the surface and adds an eye-catching visual impact.

How far from the wall, and how far apart?

Choosing between the two techniques is the easy part. Most disappointing wall lighting is not the wrong technique — it is the right technique laid out badly. Two numbers decide the result: how far the luminaire sits from the wall (the setback), and how far apart the luminaires sit from one another (on-centre spacing).

A word of caution before the rules of thumb below. Published guidance on these ratios varies between sources, and every one of them is a starting point rather than an answer. The optic in the fixture you actually specify governs the outcome, so the numbers here are for sketching a layout — confirm the final design against the manufacturer’s photometric data before it goes out the door.

Spacing for wall washing

For a smooth, even wash, a widely used starting point is a setback of roughly one third of the wall height. On very tall walls — think eight metres and up — that ratio tightens, and guidance moves toward a fifth of the height. Other sources frame the same rule as height divided by 2.5 to 3, which lands in the same neighbourhood.

On-centre spacing is then commonly set at 1.2 to 1.5 times the setback. Some guidance goes wider, allowing anywhere from a 1:1 to a 2:1 ratio of spacing to setback. The practical reading: spacing near the tight end of that range is forgiving and produces the smoothest gradient, while the wide end only works with a genuine asymmetric wall-wash optic behind it.

For a 9-foot wall, that means a setback of about 3 feet and fixtures roughly 3.5 to 4.5 feet apart. Where the wash comes from track heads rather than recessed housings, inclining the head about 35 degrees from vertical is a common starting angle for even top-to-bottom coverage.

Spacing for wall grazing

Grazing inverts the logic. The point is to skim the surface at a shallow angle so texture throws its own shadows, which means the fixture sits close: a setback of 6 to 12 inches is the usual range, and tighter installations sit closer still where maximum drama is wanted.

Spacing should be at or tighter than the setback distance — roughly a 1:1 ratio. This is the rule most often broken, and the consequences are visible from across the room: space the fixtures wider than the setback and the wall shows scallops, dark gaps between bright arcs.

The optic matters more here than anywhere else. Grazing needs a narrow, asymmetric distribution to produce the crisp shadow line that makes brick or board-formed concrete look like anything at all. Published beam-angle advice ranges from ten degrees or narrower to a broader five-to-thirty-degree window depending on how dramatic an effect is intended, so treat “narrow and asymmetric” as the specification and let the photometrics settle the number. Aim the light parallel to the surface, not into it.

Material changes the output you need. Glossy or light-coloured masonry reflects a great deal and needs a lower lumen package; matte and dark materials absorb, and tolerate more.

Scalloping and hot spots: the two things that go wrong

Almost every complaint about wall lighting is one of two faults, and both are layout problems rather than product problems.

Scalloping is the row of bright arcs with dark gaps between them. It means the fixtures are spaced too far apart for the optic, or set back too far from the surface. Changing lamps will not fix it; the spacing has to close up or the optic has to spread wider.

Hot spots are the opposite: a bright pool where a fixture sits too close to the surface, or puts out more light than a reflective material can absorb. Pale, glossy stone is the usual victim. The fix is a lower lumen package or a slightly greater setback, not a dimmer on the whole run.

Choosing the optic

Wall washing wants a symmetric or forward-throw distribution designed to push light down and out across the surface. Grazing wants a narrow asymmetric optic aimed nearly parallel to the wall. Fixtures exist in both recessed and surface-mounted linear form, as adjustable recessed housings, and as track heads where the layout may change later.

Exterior work follows the same geometry with one addition: the fixture needs an ingress protection rating suited to its position, and in-grade housings that graze a facade from below sit in exactly the place where water collects.

Common questions

How far from the wall should a wall washer sit?

As a starting point, about a third of the wall height, tightening toward a fifth on very tall walls. Confirm against the fixture’s photometric file.

What is the difference between grazing and scalloping?

Grazing is the technique. Scalloping is the defect you get when grazing or washing fixtures are spaced too far apart.

Can you graze a smooth wall?

You can, but there is nothing for the light to catch. On a flat painted surface grazing tends to reveal drywall imperfections rather than hide them, which is the opposite of what wall washing does.

Which technique for artwork?

Washing, in almost every case. Grazing rakes across the surface and exaggerates canvas texture and frame shadows.

If you are laying out either technique on a live project, we run the photometric calculation as part of the specification support we provide — it takes the guesswork out of the spacing and shows the result before anything is ordered.

To recap, if you have a piece of artwork you’d like illuminated you would use wall washing luminaires. If you have a textured wall that you really want to pop, you would use the wall grazing technique. It all depends on the wall’s texture and your personal desired effect that you’re going for.  Wall washing and wall grazing are not limited to interior applications, they can also be used to highlight a building’s exterior, and can be mounted from ground level pointing upwards. Each method is a unique way of manipulating how surfaces appear to the human eye.

Adjustable fixtures such as track lighting, are perfect for wall wash and wall grazing applications. For more a more discreet aesthetic, recessed wall wash options are available. Flux carries a variety of wall wash vs wall graze product lines that will suit your space and your budget. Please don’t hesitate to ask any questions if you’re  planning on using these techniques in your next project.

Keep reading

• How to Select Downlights — spacing, beam angle, glare, and the difference between damp and wet ratings.
• Acoustic Lighting — what it fixes, and where it stops being the answer.

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