There s an underlying moisture issue that needs to be resolved because mold requires moisture to grow and spread.
Mold in roof rafters.
The most effective way to remove mold from hard porous materials such as wood rafters and plywood roof decking is to scrub it with detergent and water while wearing a dust mask and rubber gloves.
Mold growth provided it is not just cosmetic mold which can simply be left alone can be cleaned from wood surfaces by blasting scrubbing or even simple surface wiping depending on the surface accessibility and.
Check for areas of dark discoloration staining of wood e g.
Attic mold left unchecked can grow and lead to structural deterioration of attic sheathing and roof structural elements.
Below are a few ways to check for possible roof leaks.
Attic mold is often caused by warm moist air from the house leaking into the attic space.
Rafters sheathing joists attic side of fascia boards etc.
Generally tearing off a roof and roof sheathing and perhaps roof framing to remove mold would not be sensible nor cost justified.
Mold infested drywall and insulation must be.
Bleach is corrosive and nasty to use and it kills only surface mold.
Best procedures for cleaning mold contaminated wood.
This article offers advice on cleaning mold found on surfaces of un finished wooden building materials such as framing lumber rafters floor joists wall studs and building roof wall and floor sheathing such as plywood tongue and groove pine boards and other structural wood surfaces in buildings.