The answer to 'how often to replace roof decking' is that the roof decking, also known as the roof sheathing, generally lasts as long as the roof itself, which is typically 20-30 years. The roof decking provides the base for the roofing materials and is an essential structural component of the roof. However, the lifespan can vary depending on factors like the quality of the original installation, the climate, and any water damage or other issues that may occur over time.
If the roof decking is in good condition, it may not need to be replaced when the roofing materials are replaced. But if there is significant damage, rot, or deterioration, the decking should be inspected and replaced as needed during a roof replacement project. It's important to have a professional roofing contractor assess the condition of the roof decking to determine if replacement is necessary.