What the plan knows—and what it does not.

01 · Quantities

Measurements drive the plan

Rectangular patios use length × width. L-shaped patios use two measured, non-overlapping rectangles. The selected material then supplies an example slab size, pack size and waste allowance. Orders are rounded up to complete packs.

Edging for an L-shape is shown as an upper planning allowance because the shared edge depends on the real layout.

02 · Build-up

Defaults are starting points

The default plan uses a 100 mm compacted sub-base and a 40 mm full mortar bed. Ground condition, loading and the paving manufacturer’s instructions can require a different construction.

Density values convert volume into approximate handling weight. They are planning factors rather than product certificates, so the supplier’s stated bag weight remains the ordering reference.

03 · Costs

Static ranges, deliberately not live prices

Low, expected and high fixtures represent broad UK retail and project-support scenarios. They are maintained manually and do not scrape retailers. Location, VAT treatment, pack coverage, minimum order quantities, delivery access and local disposal charges can materially change the result.

Labour remains separate because scope and site conditions vary substantially. Edit the unit-price assumptions when you have supplier or installer figures.

04 · Decision support

Confidence and difficulty are explainable rules

Confidence is reduced by unresolved site information such as unknown ground, drainage or existing surfaces. Difficulty considers scale, material, access, handling weight, cutting and unresolved risks. Neither is a hidden numerical score or a judgement of your ability.