The dimensional stability of oriented strand board (OSB) can be affected by processing variables. This study investigated the water absorption and thickness swelling of OSB based on its board layup, type of resin, resin content, and percentage of wax. The experiment data was measured inside an environmental chamber from oven dry (OD) conditions to 80% relative humidity (RH), and from OD to 90% RH. The results suggest that single layer boards and isocyanate resin provide greater dimensional stability to OSB than three layer boards or phenol formaldehyde resin. In addition, the water absorption and thickness swell data were effectively modeled by equations developed for wood fiber/polymer composites.