Builder’s Bog should be applied direct to timber, not paint. There is a good chance that the cross-linking agents in Builder’s Bog will soften the paint, and then there will be a poor bond between the two. You should make sure that all rot is removed before filling, otherwise spores remaining in the surrounding timber will continue to rot the wood around the repair. If in doubt, drill small holes in the surrounding area and inject an anti rot material into these to permeate the timber.

Then fill the holes. If using a water-based anti rot, I suggest driving plugs into the holes (dowels) and then sanding flush before painting. If you are confident you have removed all the rotted timber this step is not necessary.

Regards
Stuart Jordan
Managing Director, Chemical Specialties Ltd.
17.7.2013