Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
DD CEN TS 15083 — Natural Durability of Solid Wood Standard Series
Durability of Wood and Wood-Based Products — Determination of the Natural Durability of Solid Wood Against Wood-Destroying Fungi — Part 1: Basidiomycetes / Part 2: Soft Rotting Micro-Fungi (CEN/TS Series)
🌲 DD CEN/TS 15083 is a CEN Technical Specification issued by BSI in the Draft for Development (DD) series, specifying methods for determining the natural durability of solid wood against wood-destroying fungi. In service, wood may be attacked by fungi, and natural durability is a key basis for selecting timber species and deciding on preservative treatment. The series was prepared under UK Subcommittee B/515/1 (Preservative preconditioning and biological testing); the two documents target the two main groups of wood-destroying fungi — Basidiomycetes and Soft Rotting Micro-fungi — and are classified under ICS 79.040 (Wood).
💡 “Natural durability” is the inherent ability of untreated wood to resist biological attack; results are usually expressed as a durability class per species, used for decisions in risk categories such as outdoor and ground-contact service.
1. Series Overview and Application Context 📌
Because of differences in anatomy and extractives, wood species vary greatly in natural resistance to different fungal groups. Basidiomycetes are the main agents of “brown rot / white rot”, degrading cellulose and lignin and causing the most severe damage; soft-rotting micro-fungi slowly erode cell walls in wet, soil-contact, or chemically treated wood surfaces. Determining natural durability requires exposing standard specimens to fungi of known activity under controlled laboratory conditions and using mass loss as the evaluation indicator. The two parts specify the test conditions for each fungal group, providing the methodological basis for species selection, preservative class assignment, and product-standard referencing.
2. Series Structure and Document List 📋
| Standard | Edition | Subject | Fungal Group |
|---|---|---|---|
| DD CEN/TS 15083-1 | 2005 | Natural durability — Basidiomycetes test | Brown/white rot basidiomycetes |
| DD CEN/TS 15083-2 | 2005 | Natural durability — Soft rotting micro-fungi test | Soft-rot fungi |
3. Part 1: Basidiomycetes Test Method 🔧
Part 1 specifies the general test method for determining the natural durability of solid wood using basidiomycetes. Key points include:
- Specimens and references: prescribe species, sampling position, dimensions, and number, with reference species of known durability as controls.
- Fungal cultures: pre-culture standard strains on agar media to ensure activity and infectivity.
- Exposure: sterilized specimens are exposed to the fungus under controlled temperature and humidity for a defined period.
- Mass loss evaluation: weigh before and after exposure, assign a durability class from the mass loss percentage, and report.
⚠️ The reliability of results depends heavily on fungal activity and culture conditions: periodically verify strain infectivity using an easily rotted reference species, and repeat any test batch showing contamination to ensure valid mass-loss data.
4. Part 2: Soft Rotting Micro-Fungi Test Method 🔍
Part 2 gives a method for the attack of soft-rotting micro-fungi. Soft rot commonly occurs in long-wet, nutrient-poor environments such as soil contact or cooling-tower timber; attack occurs within the wood cell wall. The standard prescribes a test substrate of humus soil or a specific soft-rot strain, exposing specimens at the soil–water interface over a long period, then evaluating durability by bending-strength loss or microscopic damage — complementing the mass-loss method for basidiomycetes.
💡 Soft-rot tests often run longer and show greater scatter than basidiomycete tests; in engineering they are used as supplementary evidence for ground-contact / in-soil service, judged together with preservative-treatment requirements.
5. Engineering Practice 🛠️
- 🔍 Species selection: choose appropriate species for outdoor timber structures, horticulture, and landscaping based on durability class.
- 🔧 Preservative decision: for species with insufficient natural durability, determine treatment class and penetration (impregnation, pressure treatment).
- 📊 Product-standard referencing: reference the durability test methods in wood-product standards (e.g., wood-plastic composites, structural timber).
- 📋 Acceptance and declaration: use test reports to state the applicable service environment and guide correct use.
6. Frequently Asked Questions ❓
❓ Q: How do basidiomycete and soft-rot attack differ?
A: Basidiomycetes (brown/white rot) degrade cellulose/lignin rapidly and severely; soft rot slowly erodes cell walls in long-wet, nutrient-poor conditions. Test substrates and evaluation indicators differ accordingly.
A: Basidiomycetes (brown/white rot) degrade cellulose/lignin rapidly and severely; soft rot slowly erodes cell walls in long-wet, nutrient-poor conditions. Test substrates and evaluation indicators differ accordingly.
❓ Q: Why published as a “DD” draft?
A: The technical committee wished to assess the method’s practical usefulness, so it was first issued as a TS draft to gather application experience before conversion or adjustment.
A: The technical committee wished to assess the method’s practical usefulness, so it was first issued as a TS draft to gather application experience before conversion or adjustment.
❓ Q: How is mass loss converted to a durability class?
A: Map the mass-loss percentage into durability classes (e.g., very durable, durable, moderately durable, less durable, non-durable) using the standard’s threshold bands, calibrated against reference species.
A: Map the mass-loss percentage into durability classes (e.g., very durable, durable, moderately durable, less durable, non-durable) using the standard’s threshold bands, calibrated against reference species.
🔍 Q: Can the test predict actual service life?
A: Not directly. The laboratory test is a standardized relative comparison; actual life depends on service environment (humidity, soil contact, climate zone) and maintenance, so it should be assessed together with the Use Class.
A: Not directly. The laboratory test is a standardized relative comparison; actual life depends on service environment (humidity, soil contact, climate zone) and maintenance, so it should be assessed together with the Use Class.