🚨Minimum Clearance Between Wood Siding and the Roof: A Requirement More Than 50 Years Old

Since the publication of the 1970 National Building Code (NBC), Article 9.28.2.3 requires that all exterior wood cladding be installed with a minimum vertical clearance of 50 mm (2 inches) above the roof surface. This requirement is intended to prevent premature deterioration of the wood, avoid stagnant moisture, and reduce the risk of water infiltration at the junction between the roof and the wall.

However, despite this clear requirement, which has been in force for over half a century, it is common to see contractors on construction sites still failing to comply with this regulatory minimum. The long-term consequences can be costly: water infiltration, mold, premature repair of the coating, and deterioration of structural elements.

Compliance with this NBC section is not just a recommendation, but an obligation. Building owners and managers should require this compliance during any construction or renovation to ensure the longevity and performance of the building envelope.