Window install- barrier vs drainage method? – GreenBuildingAdvisor

Hello, very soon my new Andersen wood-clad e-series casement windows will be arriving to replace my existing damaged windows. I’ll be doing a full-fin replacement so interior and exterior trim will be removed. When I installed the windows 25+ years ago I used the barrier method, just as I had for years as a window installer. The tyvek house wrap was wrapped at least some into the opening, silicon sealant was used to bed the windows and I might have used tyvek tape around the fins too but can’t remember. I used fiberglass insulation all around stuffed from the inside. The house has wood siding.

I removed some of the interior trim just to see what was going on inside. All sills and jambs are dry and there’s no dust/dirt to indicate air infiltration. I live in Colorado, which is semi-arid 12” of precipitation/year, but our winds are very strong especially in the winter. 

I’m reading the Andersen instructions and it uses the drainage method where the bottom isn’t bedded in sealant and the low-expanding foam isn’t filled on the exterior half of the bottom of the window. However I did find an installation video on a different Andersen 200 series window that says either the barrier or drainage method is acceptable.

It seems like the drainage method is more popular these days but I’m questioning if the barrier method is still acceptable in my location and that I saw it worked against air and water. I found a study suggesting the drainage method isn’t as airtight unless extra backer rod and sealant is used inside but it is more forgiving from a water perspective for example if the window itself started to leak it would allow drainage. Given wind is a bigger concern than water here, I’m thinking of doing what I did originally except be sure to use flashing tape on all sides lapped correctly, and use low expanding foam fully filling between rough opening and windows instead of batting insulation. Presumably I wouldn’t do a sill flexible tape wrap because it’s not part of the barrier method but could if it is better to do so. I found Barricade brand flashing tape and conforming tape locally, which are butyl products and am told by the lumber yard they are compatible with tyvek and are highly used in our area.

Anyone have experience with this and think my approach to use the barrier method is sound? Should I use sill tape too? Thank you