Osb used for flat roof decking should be type osb 3 or osb 4 conforming to bs en 300.
Osb flat roof deck.
Thicknesses range from 5 16 to 3 4 inch and the proper one to use.
Panel selection should be made according to the category of use given in table 1 below.
Suitable for use with all bauder systems wood particle board chipboard.
Oriented strand board commonly referred to as osb is a type of engineered lumber similar to particle board formed by adding adhesives and then compressing layers of wood strands.
With edge support and the same snow load 3 8 inch osb can be used.
Osb comes in 4 by 8 foot sheets as does plywood but the manufacturing process allows the production of longer and wider ones.
Thickness and fixing recommendations are similar to those for plywood.
When designing a roof using smartply osb roof panels a deemed to satisfy approach may be employed using tables and design guidance for domestic roof applications given in bs 8103 3.
A homeowner recently wrote and asked me the following regarding osb roof decking.
Osb is widely used as roof decking material.
Ordinary chipboard is not recommended as it may absorb moisture when damp and lose its structural integrity.
Osb flat roof decks should be designed in accordance with bs 6229.