Concrete cover to reinforcement cast against the ground

75 mm cast against soil; 50 mm cast against blinding

Reinforced foundations, ground beams and ground-bearing slabs.

Where reinforced concrete is cast directly against the soil, allow at least 75 mm of cover to the reinforcement. Where it is cast against a blinding layer, 50 mm is the usual minimum.

Basis in regulation

BS 8500-1
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How to check it on site

Check the spacers on the cage before the pour — cover cannot be corrected once concrete is in.

Common failure

Mesh or cage laid straight on the ground with a few offcuts under it, leaving reinforcement almost exposed at the underside.

Last updated 23 August 2026. This is our editorial summary of publicly available regulation, not building control approval or a warranty determination.

Related dimensions at this stage

Minimum

Ready-mixed concrete temperature and curing

5 °C

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Minimum

Low-Level Protection for Timber Frame and SIPs

150 mm

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Minimum

Foundation depth during cold weather

450 mm

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Maximum

Pipe support spacing and thermal movement

110 mm

Horizontal drainage pipes, typically 110mm diameter, require support at regular intervals, often around 900mm to 1000mm centres, or at every joint/socket

Minimum

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100 mm

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Minimum

DPC and Cavity Tray Locations

150 mm

Damp-proof courses (DPCs) must be installed at the base of walls, at least 150mm above the external ground level, and linked to the damp-proof membrane (DPM) in solid floors to prevent rising damp