CRF 2025 Update 2026

DURAWORLD

A global comparison of field test methods to determine the above-ground durability of wood

Background and Project Objectives

For a reliable prediction of the performance and expected service life of wooden components, robust data on the durability of wood is required, determined under conditions that are as realistic as possible. Unfortunately, there is a perpetual dilemma in durability testing, as tests that are as close to reality as possible are only possible in the field, but these usually take a long time and incur high costs. It is therefore all the more important to have well-functioning methods for field testing, especially for above-ground scenarios, since they usually require even longer test durations due to non-permanent wetting and thus a lower decay hazard.
Worldwide, around 100 methods were described for above-ground durability testing, but only very few have been standardised. These few were basically developed for determining the relative protective effectiveness of a wood preservative (i.e. efficacy testing), but not necessarily meant for testing the durability of wood species or wood-based materials.
In Europe, there are currently two draft standards for methods that are intended to replace the much-criticized lap-joint method or at least supplement the portfolio of test methods: (1) the sandwich-test, and (2) the bundle-test. Round Robin tests have recently been initiated for each of these methods, but a comprehensive and comparative field trial is still lacking. In particular, a comparison between the two methods and the lap-joint method is needed and should be conducted at climatically very different locations. This is the only way to reliably determine the moisture load and the resulting risk of decay posed by the three methods.
Research fellows and IRGWP members from 11 countries teamed up to establish a long-term comparative field trial at climatically different locations representing 11 countries on 6 continents. DURAWORLD addresses the following research objectives:
• Comparison of methods for above-ground durability testing (i.e. sandwich, bundle, and lap-joint method)
• Comparison of assessment criteria (according to different standards, e.g. CEN, ASTM, AWPA)
• Establish assessment criteria that can be used for durability classification and decay modelling
• Input to standardisation

Experimental

The Thünen Institute of Wood Research (TI) in Hamburg, Germany, was the applicant and coordinator of DURAWORLD and is responsible for sourcing wood, producing test specimens, and shipping them to the individual research partners. In addition, the University of Ljubljana, Slovenia, the Norwegian Institute of Bioeconomy Research (NIBIO), Norway, and the Department of Primary Industries at Queensland Gov., Horticulture and Forestry Science, provided test timbers and manufactured wood specimens. Exposure and regular assessment of the specimens were the responsibility of the individual partners.
Some partners included additional wood species or wood-based materials of regional interest at their individual test sites.
The specimens are exposed on test racks, which are either 0.4 m (Sandwich method) or 1.0 m (Lap-joint and bundle method) high and assessed for signs of fungal decay (and termite attack) every 6 months. The minimum duration of the test is five years or until all specimens have failed.
The assessment is carried out according to the respective standard or draft standard (see section 2.5). In addition, the European and the American assessment scheme is applied and compared on the lap-joint specimens. For the sake of comparative analysis and as an input for decay and service life modelling decay depth and remaining cross section are determined for all specimens as well.
Specimens were made from the following six timbers and exposed at all eleven test sites:
(1) Scots pine (Pinus sylvestris) sapwood (sw)
(2) Scots pine heartwood (hw)
(3) Norway spruce (Picea abies)
(4) European larch (Larix decidua) hw
(5) European beech (Fagus sylvatica) sw
(6) Black locust (Robinia pseudoacacia) hw
(7) Gympie messmate (Eucalyptus cloeziana) hw
The total number of specimens made from these six obligatory timbers was 1,980, i.e. n=10 replicates per test method and test location. For all test methods, reference species were Scots pine sapwood, Norway spruce, and European beech sapwood to be used simultaneously.

Partners and Test Sites

The comparative field trials were conducted at eleven different test sites as summarized in Table 1.

Table 1. DURAWORLD test locations

Location	Country	Contact	Insitution	Climate
Bergen	Norway	Gry Alfredsen, Ulrich Hundhausen	NIBIO & NTI	Oceanic Cfb
Hamburg	Germany	Christian Brischke	Thünen Institute	Oceanic Cfb
Borås	Sweden	Mats Westin	RISE	Oceanic Cfb
Ljubljana	Slovenia	Miha Humar	Univ Ljubljana	Oceanic Cfb
Vancouver	Canada	Rod Stirling	FPInnovations	Warm temperate, dry warm summer Csb
Hilo	USA	Xinfeng Xie	MTU	Tropical rainforest Af
Brisbane	Australia	Lesley Francis	QDPI	Humid subtropical Cfa
Kourou	Guyana	Kévin Candelier, Jérémie Damay	CIRAD	Humid equatorial Am
Cap Estérias	Gabon	Kévin Candelier	CIRAD	Tropical monsoon Am
Jeronimo Monteiro	Brazil	Djeison Batista	FUES	Tropical savanna Aw
Tsukuba FFPRI	Japan	Hiroshi Matsunaga	FFPRI	Humid subtropical Cfa

 

Click to view images below enlarged.

 

 

 

CLICK HERE FOR ORIGINAL PLAN FOR CRF2025