About this tool Determine concrete exposure classes from environmental conditions per BS EN 206 and BS 8500-1. Select the carbonation, chloride, freeze/thaw, and chemical attack conditions — the tool gives you the applicable exposure classes with minimum cover and strength requirements.
Covers all exposure class families: X0, XC1-4 (carbonation), XD1-3 (de-icing chlorides), XS1-3 (seawater), XF1-4 (freeze/thaw), and XA1-3 (chemical attack). Each class shows typical examples to help you select the right one.
The link between condition survey findings and concrete specification — from observed environment to the spec clause you need.
How to use this tool 1. Select the carbonation exposure — based on moisture conditions (dry, wet, cyclic).
2. Select chloride and other exposures — de-icing, seawater, freeze/thaw, chemical attack as applicable.
3. Read the combined classification — all applicable classes plus minimum cover and strength for the carbonation class.
Technical information Exposure classes per BS EN 206 Table 4.1. Minimum cover (cmin,dur) per EC2 Table 4.4N for structural class S4 (50-year design life). Add Δcdev (typically 10mm) for nominal cover.
Multiple exposure classes can apply simultaneously — the most onerous governs the concrete specification.
Limitations Cover and strength values are for structural class S4 (default 50-year design life). For other structural classes or 100-year life, refer to BS 8500-1 Tables A.4/A.5.
This tool determines exposure classes only. Full concrete specification also requires consideration of workability, maximum aggregate size, and any special requirements (e.g. sulfate resistance, low heat).
Revision history 18 August 2026: Initial release
Disclaimer This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.
Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.
All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.
By using this tool, you accept full responsibility for how you interpret and apply the information provided.
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