NCC Compliance:  Roofspace Ventilation & Timber Sheathing Boards

Background

Historically, around the world it was common to see roofs that use timber sheathing boards. Using individual timber sheathing boards has become quite rare in modern construction, making up only a small fraction of new roofs.

The use of individual planks or boards is still used in historic restorations. Spaced sheathing, which leaves gaps between wooden boards, is also used where specialist roofing materials like wooden shingles, natural slate and some metal roof cladding benefit from airflow underneath the roof cladding to dry out moisture. On some high-end custom projects traditional solid wood planks still get used for their durability against moisture, or the aesthetic appeal in exposed vaulted ceilings.

More recently, by far more common, is the use of larger manufactured sheets of engineered timber like plywood, Oriented Strand Board (OSB) and moisture-resistant medium-density fibreboard (MDF).