Flood vs Graze: Two Approaches to Architectural Lighting
From Design by Application: In our Definitive Guide to Lighting by Location, we introduced facade lighting. This article compares flood and graze techniques.
Two Fundamentally Different Approaches
Flood and graze are the two primary methods for lighting a vertical surface. They produce opposite effects from the same surface, and choosing the wrong one is one of the most common facade lighting errors. Flood smooths. Graze reveals. Each has a specific application, and knowing which to use on any given facade is a core professional skill.
Flood Lighting: The Broad Wash
What It Is
Flood lighting places the fixture at a distance from the wall (typically 6-12 feet) and aims it at the surface at a moderate angle (30-60 degrees from horizontal). The beam spreads across a large area, producing even illumination with minimal shadow.
How It Works
When light strikes a surface from a distance and at a moderate angle, it fills in surface variations. The peaks and valleys of texture receive roughly equal illumination because the light is arriving from far enough away that the angle of incidence is similar across the surface. The result is a smooth, even wash that emphasizes the overall form and color of the surface rather than its texture.
Setup Specifications
- Fixture distance from wall: 6-12 feet (1/3 to 1/2 of the wall height is a common rule)
- Aim angle: 30-60 degrees from horizontal, aimed at the midpoint of the wall
- Beam angle: Wide flood (60-120 degrees) for maximum coverage
- Fixture spacing: For even coverage, space fixtures equal to their distance from the wall (a fixture 8 feet from the wall should be spaced 8 feet from the next fixture)
When to Use Flood
Smooth surfaces. Vinyl siding, painted wood, smooth stucco, and rendered surfaces do not have texture to reveal. Flooding these surfaces produces a clean, even glow that shows the surface color without emphasizing imperfections.
Color wash applications. When the goal is to bathe the facade in a saturated color (red, green, blue), flood lighting distributes the color evenly across the surface. Grazing a colored light produces uneven color distribution that can look splotchy.
Large-scale coverage. When you need to light a large facade area with minimal fixtures, flood lighting covers more surface area per fixture than grazing.
Hiding imperfections. If the facade has cracks, patches, uneven mortar, or other blemishes, flood lighting minimizes their visibility. Grazing would turn every imperfection into a visible shadow.
Flood Lighting Limitations
- Flattens the facade — removes depth and dimensionality
- Can cause hot spots if fixture spacing is uneven
- Windows become dark holes against the lit facade
- Wastes light by projecting some lumens away from the building (spillover)
- At high intensity, can create glare for approaching visitors
Graze Lighting: The Close Reveal
What It Is
Graze lighting places the fixture close to the wall surface (6-24 inches) and aims it nearly parallel to the surface. The light rakes across the surface at a sharp angle, catching every raised element and casting shadows behind every recess.
How It Works
When light strikes a surface at a shallow angle from close range, every surface variation creates a distinct shadow. A brick joint 3/8 inch deep becomes a visible dark line. A stone face that protrudes 1/4 inch from the mortar bed catches light on its face and casts a shadow below. The effect is dramatic texture revelation — the surface comes alive with depth and detail.
Setup Specifications
- Fixture distance from wall: 6-24 inches
- Aim direction: Upward along the wall (for ground-mounted) or downward (for soffit-mounted)
- Beam angle: Narrow to medium (15-40 degrees) to keep light concentrated on the surface
- Fixture spacing: 2-4 feet apart, depending on beam spread and wall height
When to Use Graze
Textured surfaces. Brick, natural stone, rough-cut stone, textured stucco, and board-and-batten siding all have depth worth showing. Grazing these surfaces is one of the most visually striking effects in exterior lighting.
Architectural detail. Columns, pilasters, cornices, and decorative trim gain dimensionality under grazing light. Details that disappear under flood lighting spring to life.
Vertical emphasis. Grazing a tall surface (a two-story chimney, a tall column, a gable wall) from the bottom creates a dramatic vertical sweep that draws the eye upward.
Feature isolation. Grazing a single wall section (a stone accent wall, a fireplace chimney) while leaving surrounding areas darker creates a powerful focal point.
Graze Lighting Limitations
- Reveals imperfections as dramatically as it reveals beauty — cracks, patches, uneven joints all become visible
- Requires more fixtures per linear foot of wall than flood lighting
- Fixture placement close to the wall can be visible in daylight
- Coverage is narrower — you light a vertical strip, not a broad area
- On smooth surfaces, graze produces an uneven gradient rather than a textured pattern
The Decision: Flood or Graze?
Surface Test
Stand at the facade in daylight and run your hand across the surface.
- If the surface has depth you can feel — mortar joints, stone faces, deep stucco texture — graze will reveal it beautifully.
- If the surface is smooth to the touch — vinyl, smooth stucco, painted wood — flood will light it more evenly.
The Material Quick Reference
| Material | Best Approach | Why |
|---|---|---|
| Brick (standard) | Graze | Mortar joints create excellent shadow pattern |
| Brick (painted/smooth) | Flood | Paint fills joints, reducing texture |
| Natural stone | Graze | Irregular faces create dramatic shadows |
| Cultured/manufactured stone | Graze | Designed to have texture; lighting reveals it |
| Stucco (rough/Spanish) | Graze | Rough texture responds well to raking light |
| Stucco (smooth) | Flood | No texture to reveal |
| Vinyl siding | Flood | Smooth surface, seams are a negative feature |
| Wood siding (clapboard) | Either | Flood for broad wash, graze to show horizontal lines |
| Board-and-batten | Graze | Vertical battens create excellent shadow lines |
| Concrete/CMU | Flood | Block joints are typically not decorative |
Condition Test
Even on a surface that responds well to grazing, the surface condition matters. Grazing a brick wall where half the mortar joints have been poorly repointed will showcase the poor repair work. Grazing a stone wall with visible patches or repairs will make those patches the most obvious feature. If the surface has condition issues, flood is the safer choice.
Combining Flood and Graze
On many homes, the answer is not either/or — it is both. Use graze on the surface sections that deserve texture revelation (the stone accent wall, the brick chimney) and flood on the sections that need broad coverage (the smooth stucco main wall, the painted garage front).
The key is transition. Where a grazed section meets a flooded section, the brightness should be roughly equal so the eye does not detect a hard line between techniques. Adjust fixture intensity to match the brightness at the boundary.
Practical Installation Considerations
Flood Light Placement
Ground-mounted flood fixtures need to be placed in garden beds, planters, or other areas where they will not be tripped over or disturbed. Stake-mounted floods work for temporary holiday installations. For permanent or semi-permanent setups, use buried junction boxes with surface-mounted fixtures.
Aim the fixture, then walk to the street to confirm the effect. Adjust from the viewing position, not from the fixture position. A flood that looks perfectly aimed from 8 feet away may produce an obvious hot spot when viewed from 80 feet.
Graze Light Placement
Graze fixtures mounted at ground level along the base of a wall should be recessed into the garden bed or hidden behind low plantings. Visible fixtures at the base of a wall look like an industrial installation, not a holiday display.
For temporary holiday installations, small LED uplights placed tight against the wall base and hidden with mulch or pine straw work well. They add virtually no visual clutter during daylight.
Fixture Count Comparison
To light a 20-foot-wide by 16-foot-tall facade section:
- Flood approach: 2-3 fixtures, placed 8 feet from the wall, spaced 8-10 feet apart
- Graze approach: 5-7 fixtures, placed at the wall base, spaced 3-4 feet apart
Grazing requires roughly 2x the fixtures of flooding for equivalent wall coverage. Factor this into your material costs and pricing.
Key Takeaways
- Flood smooths and graze reveals — choose based on what you want the surface to show
- Textured surfaces (brick, stone, rough stucco) respond dramatically to grazing; smooth surfaces respond better to flooding
- Surface condition matters — graze only surfaces that will look good under close scrutiny
- Combine both techniques on homes with mixed surface materials for the strongest effect
- Grazing requires roughly twice the fixture count of flooding — price accordingly
What's Next
Beyond main facades, structures like pergolas and porches offer unique opportunities. Let's explore these secret weapons.
Next: Structures as Secret Weapons: Pergolas, Arbors, Porches