In our bathroom, we have a wall-mounted mirror (not removable) wherein the bathroom spout and handles are mounted behind the mirror. I need to replace the valves in the faucets as they have been leaking for sometime.

I can't get a 31/32 sink wrench around the existing valve because the genius who mounted the mirror didn't cut the holes in the mirror wide enough to do so. Can almost get the wrench in, but I'm confident anymore forcing or torque will crack the mirror.

I need to widen the existing holes (1/4-1/2") in the glass around the handles to get the wrench in there.

The picture below shows all this, though it also shows part of the handle stem protruding which I can remove to do the job.

I'm thinking a Dremel with a diamond bit, allowing the mirror to cool regularly with breaks (can't use water because it'll get inside the wall), wearing lots of protection including mask for a possible mirror shatter.

The whole thing may just need to be replaced if this won't work or when I break it.

Any advice?

partial selfie of OP including a picture of the hole in the mirrored backsplash with the faucet stem

  • You could use water if you used a shop vac to suck away the excess. "un-removable" because it is glued?
    – Alaska Man
    Sep 6, 2020 at 22:04
  • I think the water would inevitably get back in there, even with a shop vac. Yes, "unremovable" because it is glued to the wall.
    – David H.
    Sep 6, 2020 at 22:09
  • 1
    "I need to replace the valves in the faucets as they have been leaking for sometime." The shop vac will get most of it, A little more water is probably not a big deal. Can you open the wall on the opposite side to access the plumbing and to assess any water damage?
    – Alaska Man
    Sep 6, 2020 at 22:32
  • I understand the confusion here now, Alaska Man. The faucet is currently leaking into the sink as a result of the of bad valves. So currently there's no water penetration into the wall itself. I can't access the other side, unfortunately.
    – David H.
    Sep 7, 2020 at 1:47

3 Answers 3


Scoring tool and string?

I have never cut a mirror with this method. If the alternative is destroying the whole thing this might be worth a try. I also humbly submit this scheme to receive insights as regards its feasibility from people more experienced than I.

Here is my mockup. The box is your mirror. The wood dowel is your pipe. My glass scoring tool is in the picture. Standing in for that tool is a stick of blue chalk. It is attached to the dowel (pipe) with a string. The string turns freely on the dowel. Don't let it wind up or you will make a spiral!

mockup of mirror with pipe

With the chalk anchored to the dowel with the string it drew a circle. If you do the same with a scoring tool and your pipe you should score a circle, and the same circle over and over. Try it first with a Sharpie on the mirror.

If you can score the glass deeply with the scoring tool you should then be able to nip it away with pliers to leave a bigger circular hole.



Here is what I did when I needed to enlarge a hole in a mirror and there was nothing to "bite" the pilot bit of a hole saw into:

  1. Tape over and around the existing hole with painter's tape. Make sure it adheres well to the glass because it is going to help take strain to keep the glass from shattering. Go out a few inches in all directions if you can. The tape on the front should combine with the reflective coating on the back to sandwich the glass and forestall cracking.

  2. Put your escutcheon back on and trace around it so you know how far you can go.

  3. Drill very small holes (1/8" worked for me) in a circle the diameter of the new hole, staying as far as possible from the outside (your drawn hole around the escutcheon will help you avoid making the circle too large). A little bit of oil on the bit helps to lubricate and cool it. Go slowly.

  4. Using tile nippers, carefully break out tiny sections between the holes. The tape and the drilled holes should keep the stress from cracking or shattering the glass.

  • OP will have a hard time getting tape on the back since this mirror was glued to the wall. Also, using the nippers to break out the pieces would be difficult, too. ;) If the piece is moveable, simply clamping it (carefully) on a piece of plywood and letting the pilot run through the plywood as a guide sounds like it would be easier...
    – FreeMan
    Oct 7, 2022 at 17:47
  • 1
    Tape goes on the front, combined with the reflective foil adhered to the back makes a decent sandwich. :)
    – Chris O
    Oct 7, 2022 at 17:49
  • Presumably you use a drill bit suitable for glass to do this, right? Interesting approach. I'd want to try it on scrap before doing it on the real mirror.
    – keshlam
    Dec 6, 2022 at 20:39

To cut a hole in a mirror requires a diamond hole saw. To freehand one like you have will be challenging. Normally a hole that big would require a drill stand, which is a specialized piece of equipment.

You might be able to find a compact sink wrench of the tubular kind.

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