That flat, builder-grade mirror in your bathroom is staring at you with its ugly, unfinished clips and despondent, naked edges. I know that look. For years, I stared at mine while brushing my teeth, thinking it looked less like a “master suite” and more like a gas station restroom.
The good news? You don’t need to rip that glass off the wall and risk seven years of bad luck (plus a massive drywall repair job). I’m going to show you how to frame that mirror right where it sits using wood trim and Liquid Nails. I once tried to use double-sided “heavy-duty” foam tape for this back in my early DIY days—let’s just say the sound of a wood frame crashing into a porcelain sink at 3 AM is a wake-up call you don’t want.
Choosing the Best Wood for Bathroom Mirror Frames
When you’re standing in the molding aisle at the big-box store, it’s easy to get overwhelmed. I’ve seen people grab that cheap, ultra-light MDF (Medium Density Fiberboard) because it’s primed and ready to go. Don’t do it. Bathrooms are essentially tropical rainforests every time someone takes a hot shower. MDF is basically a sponge made of sawdust; it will swell, warp, and crumble within a year.
I highly recommend sticking with primed finger-jointed pine or PVC molding. If you want a natural wood look, go with cedar or teak, though they’ll cost you a pretty penny. Personally, I’m a fan of a 3-inch wide fluted casing or a simple shaker-style flat board. It gives the mirror enough “heft” to look custom without making it feel like it’s wearing a heavy winter coat.
Before you buy, check every single board for “crowning” or bowing. Hold the board up like a telescope and look down the length of it. If it’s curved like a banana, put it back. I once ignored a slight warp thinking the Liquid Nails would hold it flat against the glass. Spoiler alert: the wood won’t bend to your will; it will just pull the glue off the mirror and leave a gap that collects dust and spiderwebs.
One last thing on materials: buy about 20% more than you think you need. You will mess up a miter cut. It’s a law of nature. I once spent three hours measuring, only to cut the angle the wrong way on my very last piece of expensive oak. Having a “spare” board in the garage saves you a frustrated, tearful trip back to the store in your paint-covered sweatpants.
How to Measure and Cut Miter Joints for Mirrors
Measuring for a mirror frame is different than measuring a window. You aren’t just covering a gap; you’re hiding the edges of the glass while ensuring the frame itself sits flat. You need to measure the outside dimensions of the mirror, but here’s my secret: add about 1/8th of an inch to your total length and width. Mirrors aren’t always perfectly square, and walls definitely aren’t.
I use a miter saw for this—trying to do this with a hand-powered miter box and a saw will just give you a sore arm and sloppy joints. Set your saw to a crisp 45-degree angle. The most important part of the “pro look” is making sure your corners meet perfectly. If they don’t, you’ll be staring at a gap filled with wood putty for the next decade.
When you cut, remember that the inside edge of your frame needs to be slightly shorter than the mirror’s edge so it actually covers the glass. If you cut it exactly to the mirror’s size, the ugly silver edge of the glass might still peek through. I usually aim for a 1/4-inch “overlap” onto the glass itself. This also gives the Liquid Nails more surface area to grab onto.
After cutting, dry-fit the pieces on the floor or a large table. Use a framing square to see if your corners are actually 90 degrees. If they aren’t, you might need to shave a hair off one of the angles. My first frame looked like a trapezoid because I didn’t realize my saw’s “zero” setting was actually 44 degrees. Always double-check your tools before you commit to the cut.
Pre-Painting and Sealing Your Mirror Trim
Whatever you do, do not wait until the frame is on the wall to paint it. I made that mistake once and ended up with “Navajo White” streaks all over my mirror that I had to scrape off with a razor blade for two hours. Paint the front, the back, and—most importantly—the inside edges of your boards before they ever touch the glass.
Why the back? Because the mirror will reflect the backside of the wood. If you leave the back of the trim raw or unpainted, you’ll see a weird, unfinished brown reflection in the gap between the wood and the glass. It looks cheap and screams “amateur hour.” Paint the back at least two inches in from the inner edge with a matte black or the same color as the front.
Use a high-quality semi-gloss or satin moisture-resistant paint. Since this is a bathroom, you want something that can handle a damp cloth. I’m a big fan of using a small foam roller rather than a brush; it gives the wood a factory-smooth finish that looks like it came from a high-end furniture store. Let it dry completely—like, 24 hours—before you try to glue it. Sticky paint and Liquid Nails are a recipe for a gooey disaster.
If you’re using a dark stain instead of paint, make sure to hit it with at least three coats of polyurethane. Moisture is the enemy here. I’ve seen beautiful walnut frames turn grey and moldy because the homeowner skipped the sealant. Think of the sealant as a raincoat for your hard work.
Applying Liquid Nails to Glass Safely
Now we’re getting to the “point of no return.” You need the right adhesive. Don’t just grab “General Purpose” construction adhesive. You need Liquid Nails Mirror Adhesive (LN-701) or a similar product specifically rated for mirrors. Standard construction adhesives have chemicals that can eat through the silver backing of the mirror over time, leaving you with ugly black spots.
Apply the adhesive in small, marble-sized dots or a thin, wavy bead along the back of the trim. Stay about an inch away from the edges. If you put the glue too close to the edge, it will squeeze out onto the mirror when you press it down. Cleaning Liquid Nails off a mirror is about as fun as a root canal. I learned this the hard way when I got over-excited with the caulk gun and ended up with “glue worms” visible in the reflection.
You’ll also need to account for those plastic clips holding the mirror to the wall. If your trim is flat on the back, it won’t sit flush because of those clips. You have two choices: use a router to create a “notch” in the back of the wood where the clips are, or (my favorite lazy-man hack) replace the clips with flat metal offset clips. Or, if the mirror is already glued to the wall, you can sometimes just pop the clips off right before you glue the frame on—but only if you’re 100% sure that mirror isn’t going anywhere.
Work in a specific order: Bottom piece first, then the sides, then the top. The bottom piece acts as a ledge for the side pieces. Use blue painter’s tape—lots of it—to hold the pieces in place while the glue cures. I usually leave the tape on for a full 24 hours. I once took the tape off after two hours because I was impatient, and I watched the top piece slide down the mirror like a slow-motion car wreck.
The Real Talk: What No One Tells You
Let’s be honest: your walls are crooked. I don’t care if your house was built yesterday; no wall is perfectly flat. This means when you go to put your frame on, there will be gaps between the wood and the wall. Don’t panic. This is what caulk was invented for. A thin bead of white silicone-latex caulk along the outside edge of the frame will hide a multitude of sins.
Also, if your mirror goes all the way into a corner or touches a backsplash, you might have to “rip” (cut lengthwise) one of your boards. This is significantly harder than a miter cut. If you aren’t comfortable with a table saw, you might want to reconsider the width of your trim so it fits without needing a rip cut. I once tried to rip a 4-foot board with a circular saw and no guide; it ended up looking like a mountain range.
One more “Real Talk” tip: check the clearance of your faucet. I’ve seen people build beautiful, chunky 4-inch frames only to realize they can no longer turn the hot water handle because the frame is in the way. Do a “test fit” with your raw boards before you do any cutting or painting.
Finally, keep in mind that this is a permanent-ish upgrade. Removing a frame glued with Liquid Nails is a nightmare. It will likely pull the silvering off the mirror or break the glass entirely. So, make sure you love the style before you pull that trigger.
Parting Wisdom
Framing a mirror is one of those high-impact, low-cost projects that makes you feel like a DIY god once it’s done. It’s the difference between a house that feels “rented” and a home that feels “custom.” Just remember: measure twice, paint the back of the boards, and for the love of all things holy, use the right glue.
What’s the biggest “DIY fail” you’ve had in your bathroom? I once dropped a drill bit down the drain and had to take apart the entire P-trap while my wife watched with that “I told you so” look. Tell me your stories or ask your framing questions in the comments below—I’d love to help you avoid my mistakes!
