About this tool Classify timber moisture content readings with species correction and temperature adjustment. Resistance-type moisture meters are calibrated to softwood — hardwoods read differently and need correction per BS EN 13183-2.
Results are classified against industry-accepted risk categories: safe (<16%), caution (16-20%), at risk (20-28%), and decay active (>28%). Colour-coded for instant assessment. Ten timber species with indicative correction factors.
Essential for fabric surveys, damp investigations, and timber condition assessments. The tool every building surveyor needs on their phone.
How to use this tool 1. Enter meter reading — the raw % MC from your resistance-type meter.
2. Select timber species — correction is applied automatically. Use 'No correction' for softwood.
3. Enter temperature (optional) — corrects for ambient temperature deviation from 20°C reference.
Technical information Corrected MC = reading + species correction + temperature correction
Species corrections are indicative and manufacturer-derived — resistance-type meters are calibrated to softwood, so hardwoods need correction. Temperature correction ~0.1% per °C from 20°C. Risk thresholds are industry-accepted values per BRE/TRADA guidance: <16% safe, 16-20% caution, 20-28% at risk, >28% decay active.
Limitations Species corrections are approximate. Actual correction depends on specific gravity, heartwood vs sapwood, and grain orientation.
Resistance-type meters are unreliable above ~28% MC (fibre saturation point). For higher moisture levels, use oven drying method per BS EN 13183-1.
Surface readings may not reflect core moisture. Allow pins to penetrate to at least 1/3 of timber depth for representative readings.
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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