Measuring Denman's buildings against the bylaw — carefully

2026-05-31

One of the goals of this project is to make Denman's land rules legible — not just what the bylaw says, but how the island actually looks against it. With building footprints traced from satellite imagery and parcel boundaries from ParcelMap BC, we can now measure something concrete: how far the nearest substantial building on a lot sits from its closest property line.

How it works

For every lot with a mapped building of at least 20 m², we compute the shortest distance from the building to the parcel boundary, and compare it to the smallest lot-line setback Land Use Bylaw 186 sets for that zone — 3.0 m side/rear in the R1 and R2 residential zones, larger in others. We use the smallest applicable setback deliberately: if a building is closer than even the most permissive lot-line rule, it's inside the minimum no matter which edge of the property it faces. We allow a half-metre tolerance for measurement error before noting anything.

What we found

Correction, September 10, 2026. The original post quoted 75 apparent setback flags and about 1,600 built lots without zoning. Those historical counts were not reconciled to the current Denman land-parcel population and are retired as current island figures. This correction supplies no replacement count. Consult the current scoped analysis; geometry alone cannot establish a setback violation.

The lines we won't cross

This is the most sensitive thing we've built, so we're explicit about what it is and isn't:

• It's a measurement, not a verdict. We never label a property as "in violation." A building inside the setback today may have been legally built before the bylaw (a "non-conforming" structure), may be an accessory building with different rules, or may sit on a boundary — like a shared interior line or a road allowance — that the setback doesn't apply to the way our simple measurement assumes.
• The data has slack. Satellite footprints and surveyed parcel lines each carry a few metres of uncertainty, which is exactly why we only note clear cases and show the actual measured distance so you can judge for yourself.
• The authority is the Islands Trust, not us. Every flagged lot links to the bylaw and to a way to report a correction, and the larger front-yard and sea setbacks are assessed separately as we refine the work.

The point isn't to single out neighbours — it's to hold the same public lens to every lot, with the measurement and the rule shown side by side. If we've got one wrong, tell us and we'll fix it.