Re: Inset medicine cabinet an option?
My suspicion is that your built in desk and cabinets will all be surface mounted on the wall. A standard wall cavity is 3-1/2" deep and give or take 14" wide, it is doubtful that any usable space would be had by trying to utilize the wall cavity for the desk. The way that "built in" furniture is generally done is to build niches along the wall and install normal cabinetry into the niches, giving the look of built in. An easy way to find out is to either use a stud finder (radio/electronic type, not magnetic ) or take a small nail and drive it into the drywall from the bathroom side where you'll be hanging the mirrors or cabinet. What you're doing is trying to locate the studs in the wall, and if the nail penetrates the drywall without hitting something hard, then it's likely an open stud bay. If you hit something hard then it's likely a stud.
One word of caution is that there is probably electrical and possibly plumbing in the wall/cavities where you wish to install the medicine cabinets. Depending on the size of the cabinet, you can probably work around wiring, plumbing obstacles would be a problem.
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