Materials

Paving layers and sub-base: what to record in an estimate

By Pave Measure · 9 September 2026 · 2 min read

A paving estimate needs more than the visible surface. Record each specified layer, its extent and depth, then calculate the quantities separately. Choose the construction from the site requirements and appropriate technical advice before you turn it into a price.

Describe the complete construction

Your estimate may need to distinguish excavation, the prepared ground, sub-base, bedding or other intermediate layers and the surface. The actual arrangement depends on the selected paving system. Do not copy one layer schedule into every driveway estimate merely because the area is similar.

For each item, record a material description, the area it covers, the finished depth where applicable and the basis on which it is bought. Some items are purchased by mass, others by volume, pack or individual unit. Retain the supplier’s unit with the rate to avoid multiplying a tonne quantity by a cubic-metre price.

Use a layer schedule

Record	Why it matters
Product or material reference	Makes the price traceable to the intended supply
Extent and compacted depth	Defines the finished quantity
Density or pack coverage	Connects the calculated quantity to the selling unit
Allowance and delivery	Separates the base quantity from ordering decisions
Source and date	Shows which specification and rate you used

Worked quantity, not a recommended depth

If a specified layer covers 40 m² at a finished depth of 0.15 m, its geometric volume is 6 m³. That does not establish how many loose cubic metres or tonnes to buy. Obtain the appropriate conversion and supply basis for the material. The example depth is an arithmetic input, not advice about the required depth of a driveway.

Permeable paving needs a matching system

Do not assume that a permeable surface can be placed over any conventional build-up. Marshalls describes its permeable blocks as draining through the joints into a designed sub-base, and its installation FAQs identify open-graded materials for the permeable layers. Follow the selected manufacturer’s system and site-specific design.

Keep excavation and disposal distinct

The in-place excavation volume is not automatically the volume of loose material to transport. Record the expected material, disposal route and supplier or haulage assumptions separately. Include the associated handling and access costs in the job rather than hiding them inside a surface-material rate.

Pave Measure can hold material-layer assumptions and costs with the estimate. It does not determine the engineering design. Read the drainage planning guide before treating the layer schedule as complete.

Calculate sub-base volume and mass using your own inputs in the free calculator.