Influence of check depth, redrying conditions of various ambient humidities, and the presence or absence of airflow on moisture trapping in surface checks of wood

To prevent the degradation of outdoor wood products such as wood decks, it is vital to keep them dry. Weathering induces checks on wood surfaces. Surface checks gather water and maintain a high moisture content, causing decay of the wood. Herein, water absorption and redrying tests were performed on wood specimens with slits and simulated surface checks, and the moisture content distribution on a cross section was obtained using X-ray densitometry. On redrying of the slit, two levels of slit depths (10 and 20 mm) were tested under four redrying conditions: three humidity levels with no airflow and a medium humidity level with a wind velocity of 1 m/s. The redrying rate and moisture trapping time that kept moisture content greater than 20% were used to estimate the moisture trapping risk in the surface check. The moisture trapping risk was found in the no-wind condition until 48 h redrying or longer, independent of the slit depth. Conversely, in the forced-air condition, an air-dried state was observed within 24 h. The redrying rate in the 10 mm depth slit was influenced by ambient humidity levels; however, the redrying rate in the 20 mm depth slit was unaffected. Overall, while a deeper check has a higher risk of moisture trapping, if the wood is in a poorly ventilated environment with a high ambient humidity level, a shallow check with a 10 mm depth may also be at risk.

Automated summary

Keeping outdoor wood products dry is crucial to prevent degradation, as prolonged exposure to weathering can result in surface checks and accumulation of moisture, leading to wood decay. Research findings show that, under no airflow conditions, the risk of moisture trapping in surface checks persists for 48 hours or longer, regardless of the depth of the slit. In contrast, under forced-air conditions, the wood reaches an air-dried state within 24 hours. Additionally, the redrying rate of a 10 mm slit depth is influenced by ambient humidity levels, whereas the redrying rate of a 20 mm slit depth remains unaffected.