Measure & Make
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Garden projects

A patio, with a plan.

Work out slabs, cut edges and the material volumes underneath. Start with one rectangular area and a straight laying pattern.

For a rectangular, single-size slab grid. Irregular patios and mixed-size project packs need a separate layout.

1. Your measurements

Where should I measure?
Measure rectangular patio length and width. Layer depths are measured separately in millimetres.Length (m)Width (m)One rectangular area
Measure rectangular patio length and width. Layer depths are measured separately in millimetres.

Read the patio measurement guide ↗

m
m
mm
mm
mm
Use your slab manufacturer’s specified joint.
Allowances & stock sizes
%
mm
Example depth. Ground and loading requirements vary.
mm
Example depth. Follow the chosen paving specification.

2. Your plan

Example estimate

Estimate

Project layout

Layout sketch · not an installation drawing

Your materials

    A look at the numbers

    What’s behind your estimate?

    How we count slabs

    We lay out actual slab widths with the entered joints, counting each whole or cut position as one purchased slab. We then add your extra percentage and round up. Offcuts are not reused, so the count can exceed an area-only estimate.

    If a trailing joint would leave no usable final piece, cuts are balanced across that direction. The layout is a material estimate, not a drainage or installation design.

    How we estimate the layers

    Volume = patio area × layer depth. Sub-base is a compacted volume; ask the supplier how much loose material will achieve it. Mortar volume is the complete bedding mix, not a bag count. Primer and jointing compound have separate product-specific coverage.

    Worked example

    A 4 × 3 m patio with 600 × 600 mm slabs and 5 mm joints has 7 columns and 5 rows: 35 slab positions. With 10% extra, order 39 slabs. A 100 mm sub-base occupies 1.2 m³; a 30 mm mortar bed occupies 0.36 m³.

    Supplier guidance

    Marshalls paving technical information — a supplier reference, not a product endorsement.

    Use the instructions for the particular slab range. Joint widths, bedding, priming and drainage requirements differ.