Help sealing hard-to-reach hole in the wall

I got a hole in the wall, behind the water heater.
The mice get in that way.
But I can’t get my hand in there.

How to seal it?

if you don’t find the hole on the outside they may just make another hole on the inside.

ball up some wire hardware cloth an stuff it in using a broom handle, pliers, any implement.

Depending on how hard it is to reach, coarse steel wool may be easier than hardware cloth to jam in the hole.

Move the hot water heater. It’s not that hard. Disconnect the hot and cold pipes, and drain it. The tank itself isn’t all that heavy.

I’d cut back the drywall. See if you can tell where they are getting in from the outside. Some scrap wood would patch the outside hole (from the inside). Leave some rat poison inside the wall cavity. Patch the drywall.

Can you shoot that expanding/solidifying foam crap there? I used that to fill a hole where mice were entering 6 years ago. It’s still holding up today.

Dump in poison
Slide new sheet of drywall sideways behind heater, and secure as well as you can - if you can’t get at least both edges screwed/nailed down, it will look like crap.

If pretty is critical, remove water heater.

Unless it is gas and you:

  1. can’t flex the gas line enough to get the heater far enough
  2. you don’t trust yourself opening and re-closing the union on the gas line.

In which case see other replies

What kind of wall is it?

This gets my vote for being the easiest solution, especially if looks are not all that important.
If the stuff expands too much and protrudes outside of the hole, simply take a carpenters hand saw and hold it flat against the wall and trim the stuff off, flush with the surface.

Assuming we’re talking about a hole an inch or two in diameter.

Cut the top and bottom off a soda can and cut down the side - flatten it out and cut a piece of metal about an inch bigger than the hole all around.
Use double-sided foam tape to stick the metal onto a wooden lath or anything that will allow you to place the metal over the hole.
Apply fast-setting epoxy to the other side of the metal and press it in place over the hole.
When the glue cures, it should be possible to pull off the sticks and foam tape, leaving the hole patched with a piece of metal.

Did that with some holes, can’t reach to this one.
Is there a way to stretch out the little plastic hose?


I don’t got the tools, nor any experience whatsoever.
And my manual dexerity is impaired by a severe childhood neurological injury. No real tool handling skill here.

Great plan, but there’s a pipe in the hole.

Is this a pass through hole for a pipe? What type of wall is it?

Ah, didn’t realise that.

To what extent can you actually reach or see the hole? If you remove the casing of the water heater, does this improve access?

I’m gonna renew the steel wool suggestion. You can pull small pieces off, stick them on the end of an unbent coathanger, and stuff them around the pipe. That should discourage them. You don’t have to get a great deal of it in there to do the trick, and it seems accomplishable for someone with your condition…right? Certainly something a friend could help with too.

WARNING: Use gloves to handle the steel wool or you’ll be sorry.

Are you renting? Can you get the landlord to do something?

Problem solved, I think.
I got a can of foam crack sealant, & 3 feet of plastic tubing.
Connected it to the sprayer with duck tape.
It leaked, but I laid a drop-cloth down, JIC. Also wore rubber gloves.

The hole appears sealed, although it’s hard to tell at this angle.

Side note–I managed to set 2 snaptraps without catching my own fingers, a personal best! :smiley: