Rotten timber is highly infectious to other timber. Cut out 45cm on either side of rot and burn infected timber.
Treat all surrounding timber as if it were heavily mould infested with Resene Moss & Mould Killer diluted with 20% solution and 80% water.
Scrub clean with Resene Roof Wash and Paint Cleaner and thoroughly rinse with cold water. Treat all bare timber in the vicinity and replacement timber with Resene TimberLock. Preprime all sides of replacement timber before installation. Rusty nail-heads may be accompanied by rot around the body of the nails.
Repaircare can be used to fix rotten timber. View an example of rotten windows repaired with Repaircare.