To begin, rip the top and side jambs to the thickness of the wall framing plus the exterior wall sheathing. The cement board will lap over the jambs. The windowsill should also be flush with the interior framing, but hang over the outside sheathing about 1-1/2 in. and have a 5-degree slope toward the outside to help shed water. To keep water from running behind the siding as it drips off the edge, cut a shallow groove (or saw kerf) in the bottom lip (Fig. A). Also, remember to flash behind the trim to keep the window watertight. Trim the window exterior to match the house, using caulk to seal between the trim and siding.
Interior bathroom demolition costs $1,000 to $2,300. Prices can go higher if you’re removing and moving walls to create a different footprint. For the experienced DIYer, this is a good place to save money by doing it yourself or assisting the contractor. However, demo can get expensive quickly if you take out a load bearing wall, cut electrical lines or break a water pipe. Avoid the risk by hiring a pro.