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Durability ClassifierNatural Decay Resistance Classifier

Classify the natural durability of wood against fungal decay and insect attack using the EN 350 standard. Get the durability class, expected service life and suitable use-class applications.

EN 350 Class 1-5Service Life EstimateUse Class MatchingTreatment AdvicePDF Report
DUR

Durability Classifier

Natural Decay Resistance Classifier

Wood and Application

Sets baseline durability.

Sapwood is Class 5 for nearly all species.

Durability Adjustment

Auto-set by species; adjust if known.

OK
Durability Classification Results
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EN 350
Durability Class
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years
Est. Service Life
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match
Use Class Fit
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rating
Recommendation
PropertyAssessmentDetail
Classification Logic
About Durability Classifier
Natural durability is a wood's inherent resistance to decay fungi and wood-boring insects, without any treatment. The European standard EN 350 grades heartwood durability from Class 1 (Very Durable, like Teak and Ipe) to Class 5 (Not Durable, like sapwood and most softwoods). Matching durability class to the EN 335 Use Class of the application is the foundation of specifying wood that lasts.
Where Is This Used?
Exterior Joinery SpecDecking + CladdingLandscape TimberMarine ConstructionArchitecture + SpecsImport Compliance
Standards and Formulas
EN 350: Durability Class 1 (Very Durable) to Class 5 (Not Durable)EN 335: Use Class UC1 (dry interior) to UC5 (marine)Service life ~ base_life(class) x use_factor x climate_factorSapwood is rated Class 5 for almost all speciesTreatment can upgrade effective class by 1-3 levels
Frequently Asked Questions
Why is sapwood always non-durable?
Sapwood is the living outer wood that transports sap and stores starches and sugars - exactly the food that decay fungi and insects need. Even in highly durable species like Teak, the sapwood is Class 5 and must be excluded or treated for any exterior or ground-contact use.
Can I use a Class 3 wood in ground contact?
Not without treatment. Ground contact (Use Class 4) demands Class 1-2 natural durability, or proper preservative treatment. A Class 3 wood like Sapele in ground contact will fail in a few years. This tool flags the mismatch and recommends either a more durable species or treatment.
How does tropical/monsoon climate affect durability?
Warm, humid conditions accelerate fungal decay dramatically. A wood that lasts 25 years in temperate Europe may last only 10-15 years in coastal monsoon India at the same use class. This tool applies a climate factor so Indian specifiers get realistic service life estimates.
ResourcesView the formulasFormula Library
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