I am in the process of replacing pulley-style windows in a 1941 house. The siding is asbestos and I do not want to remove it in order to properly flash the window (using flex tape and weather barrier). The window buildouts, as you probably suspected, are bad and there is weathering (no rot thankfully) around the adjacent siding sheathing which extends slightly past the siding itself. I want to protect the sheathing and surrounding casement but am not able to given the asbestos siding.
I know this is going to be controversial, but I am thinking about using the 5-gallon tub of premium elastomeric roofing sealant on all of the wood before putting in the new windows. I have thought carefully about this as I don’t want to create a situation worse than just doing nothing. The only issue I have been able to come up with is the possibility of moisture getting trapped between the sealant and wood and actually accelerating rot. However, given the nature of the sealant for roofing applications, I do not think this will become an issue.
Furthermore, as I apply the sealant, I can attempt to make sure there is still a path for water to run out if there are penetrations. I have done extensive research on the proper way to replace old windows but all the information I have seen so far involves extensive removal of the siding at least a few feet away from the window.
Your insights are greatly appreciated.
