I had a custom home built nearly 5 years ago and when we were asked if we wanted trim around our windows I was counting the cost and said no. Stupid! My wife and I realize our mistake, but not sure what avenue to take to correct. Siding is Fiber cement, upscale in every other way, but windows look unfinished. HELP!
Yes you can add trim now. This can be as simple (picture frame), or as complex (craftsman style with sill and head detail) as you want to spend. Either way, make sure the installation includes head flashings, to direct the water over the head trim and onto the window. These would be tucked into slits cut in the vapor barrier and over the trim and window flange. The trim should be primed all sides and "stand proud" of the siding profile a minimum 3/16". Back bevel the bottom trim it's length or run a caulk bead along that front edge (drip edge) to direct water away from the caulked siding/trim joint. The material may want to match any other trim- wood, rough sawn, smooth, plastic, etc.- on your house.Be safe, GBAR