## 2 Materials and Methods
### Test Set-Up for Built-In and Leakage Moisture in Wall Structures  
The built-in moisture test aimed to explore the drying rates of initially humid wood frames in wall structures. The wood frames from Nordic softwood were first moistened in a weather room with active water sprinkling and a relative humidity close to 100%. The vertical moisture flow in the humidity room was measured with the mass change of a paper towel. The moisture flow was approximately 0.3 mm/h. The humidification period lasted 16 days, after which the wood frames had an initial average moisture content of 26-28 percent by weight. The humidification period is equivalent to a rainy and foggy building phase. The drying phase of the built-in moisture test was assembled into an Arctest-1500 environmental test chamber. The test included four wood frame wall structures for which wall 1 served as a baseline wall (BL) and the others as highly insulated walls (Table 1, Figure 1). The selected HI wall compositions are common in Finland. The baseline wall was a common structure in Finland until the year 2010. The wood frames were initially cut precisely to fit exactly into the wall framework, leaving a minimal gap against the plywood frame. The plywood frame was coated with a polyethylene (PE) foil on all sides to prevent moisture transfer into the frame. Thereby, the test walls corresponded to high wall sections with little vertical moisture transfer. The indoor conditions on the warm side of the experimental walls was constructed with a PE-foil assembled in a wood frame. The ventilated cavity and the facade cladding material was omitted from the test structures. Thereby, the test represented structures with adequate ventilation behind the facade cladding. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Test Wall**} & **U-Value** & **Sd-Value of Materials** & **Sd-Value of Vapor** & **Added Moisture During** \\  & **[W/m\({}^{2}\)K]** & **Outside Wood Frame [m]** & **Barrier [m]** & **Humidification [g]** \\ \hline BL (baseline) & 0.22 & 0.073 & 76.5 & 1096 \\ HI 1 & 0.12 & 0.099 & 76.5 & 809 \\ HI 2 & 0.12 & 0.099 & 0.3–25 & 838 \\ HI 3 & 0.12 & 0.172 & 76.5 & 806 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Hygrothermal properties of the test walls in the drying phase of the built-in moisture test. The Sd-value stands for the water vapor diffusion-equivalent air layer thickness. Both indoor and outdoor environments were equipped with thermo- and hygrostats to create a specific temperature and humidity condition. The moisture content of the wood frame was measured from a total of 24 points with Scantronik's (Zorneding, Germany) Material Moisture Gigamodule and Thermofox equipment, measuring moisture content (MC) based on the material's electrical resistance. The measurement depth was selected to be 10-20 mm from the wood surface. The measurement method results in the maximum moisture content from the measurement area. The precision of the equipment is 1 weight-% below 85% relative humidity and between 85-100% relative humidity the precision is 1-4 weight-%, as the precision declines somewhat linearly towards 100% relative humidity. The equipment measurement range is 6-90 weight-%. The MC as weight-% was calculated from the electrical resistance according to [14], considering the wood species and temperature. Temperature and humidity were measured, from the middle height and 5 cm upwards from the bottom of the test walls, with Vaisala HMP44 probes. The accuracy of the relative humidity measurement is \(\pm\)2% between 0-90% relative humidity and \(\pm\)3% between 90-100% relative humidity. The probes were calibrated in salt solutions before the measurements. The leakage moisture test was performed to evaluate the drying ability of the wood frame wall structures exposed to the infiltration of rainwater into the stud space. This test was performed with the same test structures as in the built-in moisture test (Figure 1). The leakage test was started after the built-in moisture had dried off.