*2.2. Outdoor Exposure*

Figure 1 shows the wooden model house unit at the Department of Wood Science and Technology in Ljubljana, Slovenia (46◦02 55.7" N, 14◦28 47.3" E, elevation above sea level 293 m), where the in-service performance of decking elements was tested. This object has been used in several studies. The objective of this model house was to comprehensively assess the technical and aesthetic service life of wood. The aesthetic service life has been reported already [23], so this manuscript focusses on the technical service life only. The average temperature in Ljubljana is 10.4 ◦C, the annual precipitation is 1290 mm and the Scheffer Climate Index is 55.3. The test specimens, with a cross section of 2.5 <sup>×</sup> 5.0 cm2, were exposed on the decking of the model house. At least seven samples of the wood material were exposed on the decking. The in-service testing started in October 2013 and the prime objective was to monitor the occurrence and development of decay (functional service life) and the moisture performance. Decay was visually evaluated annually and rated (0—no attack; 1—slight attack; 2—moderate attack; 3—severe attack; 4—failure) as prescribed by EN 252 [24]. Only the decking specimens were considered within this study.

**Figure 1.** Wooden model house unit in October 2013 at the beginning of the exposure. Yellow arrow is pointing north.

Moisture content (MC) during service life is one of the indicators of moisture performance. For MC measurements, resistance sensors were applied at 19 positions, with one pair of sensors for each wood material. They were linked to a signal amplifier (Gigamodule, Scanntronik, Zorneding, Germany) that enabled wood MC measurements between 6% and 60%. Pairs of stainless-steel screws with a diameter of 3.9 mm and length of 25 mm served as resistance electrodes, fastened in the middle of the tangential surface with a longitudinal distance of 32 mm between them. The screws were insulated with a universal heat-shrinking tube, except for the tip, which served as the point of measurement. Hence, the measurements take place approximately 10 mm below the surface. Sensors were located at least 20 cm from the cross section. The electrical resistance of the wood was measured every 12 h, and these data were used for calculating the wood's MC. Resistance characteristics for each material were determined as reported by Kržišnik et al. (in press) [25], using the methodology described by Brischke and Lampen [26] and Otten et al. [27].
