External timber framed walls

6.2.7Sheathing

Sheathing shall be durable and capable of providing structural resistance to racking

The following materials are acceptable:

PlywoodBS EN 636-2 or BS EN 636-3
Oriented strand boardBS EN 300 type OSB/3 or 4
Moisture-resistant chipboardBS EN 312 type P5 or P7
Medium boardBS EN 622-3 type MBH.HLS1 or MBH.HLS2
Impregnated soft boardBS EN 622-4 type SB.HLS
Proprietary sheathing materialsTechnical Requirement R3 and used in accordance with the assessment.

Plasterboard may contribute to a buildings racking resistance when used in accordance with PD 6693-1. Particular attention should be taken when it comes to walls that are not separating walls comprising two or more built-up layers of plasterboard having a minimum thickness of 30mm and walls where plasterboard is combined with a wood-based sheathing on the same wall diaphragm where limitations or exclusions apply.