Exterior Trim replace

For this project a customer had a piece of exterior siding trim that had “exploded” at a knot in the trim wood. Upon a deeper look it was clear that those who installed the siding left a large gap between the siding and trim wood resulting in over 1/4” of caulking to fill the gap. This caulking had failed because it was installed beyond the recommended 3/8” gap. Over time the expansion and contraction of the surrounding wood will pull away from the caulk as it dried out and looses its ability to stretch. Once this happens water is able to penetrate behind the caulking and soak into the wood behind. Also the wood was possibly installed while quite wet and as it dried out after being painted the wood fibers contracted pulling away from the knot which is more dense allowing for water to penetrate there. See the images below that show the caulking pulling away from the wood and the “exploded” wood around the know.

The solution for this was to remove the rotted board, trim back some of the siding boards to create a consistent edge and then scribe cut a new board to match the the correct 1/8” gap between the cement fiber board siding and the trim. We tapped everything off, caulked and painted the new trim board. New paint always looks different than existing paint due to UV exposure. We always strive to create a clean break between painted surfaces. Taping allows for crisp clean edges instead of feathered brush strokes that would be more noticeable.