What fire rating do I need?
Life safety is the paramount objective of fire safe building design. Buildings should be designed and constructed in such a way that the risk of fire is reduced and, if a fire does occur, the spread of fire is inhibited.
For many domestic and smaller commercial projects, timber cladding can be used without a flame retardant. Building regulations impose certain restrictions on the fire class of cladding elements, in certain situations (eg close to a boundary), and depending on the use class of the building (eg domestic / commercial / residential care etc).
Fire regulations are devolved, and the building standards differ slightly for Scotland, England & Wales.
Always consult Building Control for advice on your project.