Siding exposure & reveal by material reference
Pick a material and read its typical exposure — the visible height of each course — and its coverage per unit. Exposure sets how many pieces cover a square, and how much labor it takes.
Vinyl lap (double-4") has about a 8" per panel exposure. Exposure (the visible height of each course) sets how many pieces cover a square — a smaller exposure means more pieces and more labor; use the exposure the manufacturer specifies.
1 Enter your numbers
Exposure (also called the reveal) is the visible height of each course of siding once it is installed and lapped — a double-4″ vinyl panel, for example, shows 8″ of face (two 4″ courses). Exposure is not a cosmetic detail: it is the single variable that decides how many pieces cover a square. A smaller exposure means more courses per wall, more pieces to handle and cut, and more labor — which is exactly why cedar shingles at ~5″ exposure cost more to install than a wide lap.
This reference pairs each common material and profile with its typical exposure and its coverage per unit (per box, per bundle, or by the square). Use it to sanity-check a quote’s piece count, to understand why two materials at the same price per square foot can differ in labor, and to feed the coverage number into the boxes-by-material calculator and the coverage-per-square reference. The values are labeled planning typicals — the exposure the manufacturer specifies for your exact product always wins.
Formula
This is a lookup against a labeled convention, not arithmetic:
exposure = coverage_table[ material ].exposure, coverage = coverage_table[ material ].sqft_per_unit
The relationship that matters downstream is the identity used by the quantity tools: pieces ≈ wall_area ÷ (piece_face_width × exposure), and units = ceil( area × (1 + waste) ÷ coverage_per_unit ). Smaller exposure → more pieces → more labor.
Worked example
Select Vinyl lap (double-4″): the tool reports an 8″ per panel exposure and ~200 sq ft per box (two squares of coverage). Select Cedar shingle / shake instead and the exposure drops to about 5–8″ with ~25 sq ft per bundle — roughly four bundles to a square at a 5″ exposure. Same wall, far more pieces and far more labor for the shingles: the exposure is the reason.
Exposure drives piece count and labor
Read exposure alongside coverage, not instead of it. Points that trip people up: the double-4″ / double-5″ naming refers to the panel’s face profile (two courses per panel), so the exposure is 8″ or 10″, not 4″ or 5″; cedar and shake exposure is set by the coursing you choose within the manufacturer’s allowed range, and a smaller exposure raises both piece count and waste; and fiber cement, wood and engineered lap are usually quoted by the square rather than a fixed box, so confirm the pieces-per-square for the exposure you install. These are labeled planning typicals, not a certified spec — the manufacturer’s installation instructions govern the actual exposure, coverage and fastening, and pre-1978 lead paint on old siding is an EPA RRP matter for a certified firm.
Reference table
| Material | Typical exposure | Coverage per unit |
|---|---|---|
| Vinyl lap (double-4") | 8" per panel | 200 sq ft / box |
| Vinyl lap (double-5") | 10" per panel | 200 sq ft / box |
| Insulated vinyl | 6–7" | 200 sq ft / box |
| Cedar shingle / shake | ~5–8" | 25 sq ft / bundle |
| Fiber cement lap plank | 4–8" (plank) | 100 sq ft / square |
| Engineered wood lap | 4–8" | 100 sq ft / square |
| Wood / cedar bevel lap | 4–8" | 100 sq ft / square |
| Steel / aluminum lap | 8" | 100 sq ft / square |
| Board & batten | board width | 100 sq ft / square |
Labeled published planning snapshot — 1 square = 100 sq ft. Fiber cement, engineered wood, wood and metal lap are commonly sold and quoted by the square (100 sq ft) rather than a fixed box; confirm the exact pieces-per-square and stated coverage on the manufacturer’s installation instructions.