@Robbie Wyness
Generally, when a window company replaces your old windows and puts in new ones, they wrap the exterior wooden frame of the window using a siding bender and vinyl-covered aluminum trim coil. This covers the exterior wooden trim of the window and makes it match the new windows now in the frames. The window companies like to say that this makes the window exteriors "zero maintenance." This is very popular in rentals with hands-off or absentee landlords who don't handle much of their own maintenance.
We do business in Pittsburgh, the city proper and the immediate suburbs. The city in these areas was built up from 1890-1930, and most of the single-family homes and small multifamilies we work on are from this period. We typically prefer brick-veneered properties from this era, and are plenty of them in this city. Pittsburgh has unusually wet weather due to its location. There's not really that much snow, but there's a lot of rain and a lot of freeze-thaw cycles. Water gets into everything.
Most brick veneers back in the day were done with a slight standoff from the wooden boards that made up the exterior siding of the home. Exterior wooden window trim typically covers this gap. As the years pass, the wood tends to rot down around the brick and expose the gap, and water starts to get in between the exterior boards and the brick. A large enough influx will cause the mortar between the bricks to start failing, and bricks near the window start to come loose.
Well, when a window company comes in to replace old windows with new ones and wraps the windows in pieces of aluminum trim coil, they typically do no maintenance to the exterior wooden trim underneath. They seal the aluminum wrapping with the cheapest caulk they can get away with. What happens is that the caulk starts failing in just a few years. Water starts to get into the gap and from there into the standoff and gets busy working on loosening the bricks. But if you, the landlord, aren't looking for it, you typically can't see it until the bricks start coming loose and real damage is done. The wrapping itself doesn't degrade, it offers no clues or warnings about what's happening unless you look very closely.
With typical modern double-sash vinyl replacement windows, maintenance on wooden exterior window trim goes from being difficult to routine -- you take out the sashes from the inside and work on the wood. You stick your head out the large window opening paint the exterior trim, replace the parts that are rotting out, recaulk the window with good silicone as you see fit. Exterior wooden window frames in homes and rentals like this don't really need to be wrapped to minimize maintenance, as I see things, not if you're putting in the kind of modular replacement windows most people put into their residences and rentals.
The compelling maintenance reasons to wrap soffits and fascia are still there, replacement windows or no. You've got to break out ladders and scaffolding to get to them. With the ease of working on existing exterior wooden trim when you put in modern windows with removable frames, in a working brick veneered rental property of a certain age I don't see any good reason to give up close oversight of the condition of exterior window trim and allow the possibility of water getting into the standoff between the bricks and the exterior boards by having the window frame wrapped in aluminum and not-so-well-sealed with cheap caulk.
