A mirror-fronted medicine cabinet does two jobs in one: it stores the daily bathroom essentials and reflects light back into the room. Homeowners can buy a ready-made unit, or they can build one that fits the exact opening, the exact wall depth, and the exact finish they want. The project suits new and experienced DIYers alike, because the box is simple, the joinery is basic, and the payoff shows up every morning.
The build borrows techniques from larger cabinet projects. Frameless cabinet construction for custom woodworking teaches the same flat-panel methods you will use here: square cuts, clamped glue-ups, and hardware that does the aligning for you. Once you have built one box, the same skills scale up to vanities, shelves, and full wall units.
Plan the Cabinet and Organize Your Workspace
The first decision is mounting style. A surface-mounted cabinet attaches directly to the wall and sits proud of it, which is the most straightforward method, but the entire box protrudes into the bathroom. A recessed cabinet hides inside the wall between the studs, which adds storage depth without stealing floor space.
The recessed route starts with the studs. Measure the spacing first: wall studs are commonly 16 inches on center, which leaves a 14.5-inch opening between two studs, or 22.5 inches on a 24-inch layout. The cabinet width must fit inside that opening, so measure before you buy anything.
- Measure the stud spacing, then the opening width and depth.
- Choose the cabinet width, height, and depth to fit the bay.
- Decide the door layout: one door or two.
- List every material and tool, then gather them in one place.
A clean bench makes the difference between a square cabinet and a frustrating one. Building your own tool storage cabinet for an organized workshop is a good warm-up project, because it gives every clamp, driver, and square a home before you start cutting parts for this build.
Match the depth to the wall cavity
A 2×4 wall offers about 3.5 inches of cavity depth, so a recessed box is typically 3.25 to 3.5 inches deep plus the door. Interior walls framed with 2×6 studs give you 5.5 inches, enough for a deeper cabinet. Confirm the wall construction before you commit to a design.
Surface-mounted depth is your choice
A surface-mounted cabinet can be 4, 5, or even 6 inches deep because nothing limits the protrusion. Deeper cabinets store more, but they also crowd small bathrooms. Match the depth to what you actually keep inside, not to what the store displays.
Measure the Opening and Cut the Parts
For a recessed install, cut the drywall opening only after you confirm what is behind it. Mark both stud edges with a stud finder, then cut the drywall with a keyhole saw or an oscillating multi-tool. The opening should match the cabinet box plus a small allowance for shims.
Reference projects cover the same sequence, including the medicine cabinet project from This Old House, and they all agree that order matters more than speed: drywall first, then the box, then the door. Cut the parts to the sizes in the table below, adjusted for your measured opening.
| Part | Material | Quantity | Size (adjust to your opening) |
|---|---|---|---|
| Sides | 3/4-inch plywood | 2 | 3/4 x 4 x 24 inches |
| Top and bottom | 3/4-inch plywood | 2 | 3/4 x 4 x 14 inches |
| Back panel | 1/4-inch plywood | 1 | 14 x 24 inches |
| Door frame | 3/4-inch hardwood | 4 | Mitered to the door size |
| Mirror | 1/8-inch or 1/4-inch mirror | 1 | Cut to the door opening |
Cut the sides square first
Use a track saw, a table saw, or a circular saw with a straightedge guide. Check every panel with a square before you move on, because one out-of-square side throws the entire box off. Cut the back panel last so it can be trimmed to fit any small drift in the assembly.
Label every part
Mark each piece with its position, left and right, top and bottom, so assembly goes quickly and you never glue the wrong faces together. A pencil mark on the inside face costs two seconds and prevents a whole afternoon of regret.
Assemble the Box and Build the Door
Pocket holes make the box joint forgiving for beginners. Set the pocket-hole jig for 3/4-inch material, drill two holes at each corner, apply wood glue, and drive 1-1/4-inch screws. Clamp the box square before the glue sets, then measure the diagonals: equal diagonals mean a square box.
The door deserves the same care as the box. Cabinet doors are where woodworking shows, and a bar cabinet featuring a stained glass door demonstrates how much a well-made door changes a piece of furniture. A mirror-front door uses the same frame-and-panel logic, with the mirror standing in for the panel.
Frame-and-panel door with a mirror panel
Build a simple frame from 3/4-inch hardwood with mitered or butt joints. Rabbet the inside back edge so the mirror sits flush, then hold the mirror with small clips or a bead of mirror mastic rather than screws. Leave a hair of clearance around the glass so the frame can move with humidity.
One door or two
Wide openings work better with two doors, each about half the width. Two doors reduce the swing radius and keep each mirror panel small enough to handle safely. Plan the frame widths so the two doors meet in the middle with an even reveal.
Install the Cabinet in the Wall
Slide the box into the opening and check it for level and plumb. Shim the sides and bottom, then screw through the box sides into the studs. The sequence mirrors the steps for installing a recessed medicine cabinet in your bathroom wall: check for obstructions, fit the box, secure it, and trim the edges.
- Confirm the opening is clear of pipes, wires, and ductwork.
- Dry-fit the box and mark the shim points.
- Level the box, insert the shims, and screw into the studs.
- Trim the opening with casing or a drywall flange.
Check what is behind the drywall
Look for electrical cables, supply lines, and drains before you cut. A borescope or a flashlight and a small pilot hole can save you from cutting into a wire. If you hit an obstruction, shift the opening or switch to a surface-mounted design.
Insulate and air-seal the cavity
A recessed cabinet is a hole in the building envelope. Pack loose insulation around the box and seal the gaps with caulk or spray foam to stop drafts and moisture from the wall cavity. This step matters most in bathrooms on exterior walls.
Attach the Mirror, Hang the Door, and Finish
Apply the mirror with mirror mastic in a grid pattern, press it into the rabbet, and hold it with temporary tape until the adhesive cures, typically 24 hours. Use safety-backed mirror or apply an adhesive safety film so a break does not shower the sink with glass.
Then hang the door and adjust the hinges. The same pocket-hole joinery used on a console cabinet with cane webbing and pocket-hole joinery gives you clean, screw-hiding connections, and self-closing hinges remove the guesswork from alignment.
Finish before you hang the hardware
Paint or stain the box and door before installing the mirror and hinges, or at least before final assembly. Mask the mirror face if you finish after installation, and give every coat its full dry time between passes.
Hinge adjustment in three passes
Adjust the door in three directions: in and out from the box, side to side, and up and down. Make the in-out adjustment first, then side to side, and check the reveal between the doors last.
Organize the Interior and Maintain the Cabinet
A cabinet earns its place when the inside stays usable. Install adjustable shelves so tall bottles fit on one level and small jars on another. Door racks add a third storage plane for tubes and brushes, and a shallow lip on each shelf keeps items from rolling out when the door closes.
Keep the cabinet dry and ventilated. Humidity degrades paper labels and some medications, so run the exhaust fan during and after showers and wipe spills promptly. The same discipline that keeps a cleaning supply cabinet that works for any home organized applies here: group like items, label the shelves, and return everything to its spot after use.
What belongs in a medicine cabinet
- Daily medications and vitamins
- First-aid basics: bandages, antiseptic, tweezers
- Grooming items you reach for every day
- Small bottles and tubes that fit the shelf height
What stays out
Store temperature-sensitive medication away from the bathroom’s heat and humidity, keep sharp objects in a closed container, and leave nothing in the cabinet that you would not want a child to reach.