See from the photos, I noticed a soft spot in the window trim and then proceeded to remove all of it. Plan is to replace it with PVC trim instead.
The wood I removed definitely was moist in some areas and I found some millipedes in the wood. It doesn’t appear the tar paper was penetrated except where some nails were through it. So I think behind it would be ok. But I’m not 100% sure.
How far would you go to look for moisture and rot? Would you cut away the tar paper? I am concerned that would weaken the barrier it provides.
Also, with the window trim off before I replace it, would it be worth putting some BlueSkin under the siding and over the window flange? Or should I not do that.
I was also going to get an aluminum drip edge and stick that under the siding for above the window.
I will need to glue 2 of the boards together with PVC cement to get the thickness I need and then cut to fit. I plan to screw into place and then use window caulking to caulk around the trim and the screw holes.
Any thoughts of suggestions for my plan?
I mainly want some input if I should cut the current tar paper and if I should blueskin or not. See the imgur link for photos