Landscaping & Outdoor

Landscaping quantities are dominated by depth and by settlement, and both are routinely underestimated. Mulch, topsoil, gravel and turf dressing are ordered by volume but consumed by area at a depth that compacts after placing — a bed dressed to a nominal depth needs materially more material than the arithmetic suggests once it has been walked on and rained on.

Hardscape and irrigation calculations here separate the surface from what is under it. A paved area is a base course, a bedding layer and a wearing surface, each with its own depth and its own compaction behaviour, and pricing the visible layer alone understates a patio by a wide margin. Where a page covers only the surface, it says so.