Utility penetrations
Every line that comes into the house, from power and gas to cable and phone, makes a hole. Those holes are rarely sealed well.
Where to look
- Where power, cable and phone lines enter the wall.
- Around the electric meter, its conduit, and the gas line.
- Where pipes or conduit run up into the soffit or eaves.
- Old holes from lines that were removed but never patched.
The rule of thumb: if a gap is about the width of your finger, a mouse can use it.
Why mice use it, and the common mistake
Why mice use it
Utility holes are drilled larger than the line, and installers rarely come back to seal them. They're often low on the wall or tucked under the eaves, right where a mouse travels.
Common DIY mistake
Foaming around the line and calling it done. Foam alone gets chewed through, and it hides the gap instead of closing it.
The lasting fix
Close it with stainless steel or galvanized hardware cloth, or exterior-grade metal, sealed in with exterior-grade adhesives and sealants.
The lasting fix, step by step
Find every penetration
Follow each line to where it enters the house, and look for old, unused holes too.
Check the size of the gap
If the gap around a line is about the width of your finger, it needs sealing.
Fit metal around the line
Fit stainless steel or galvanized hardware cloth around the line, without pinching or damaging it.
Seal it in
Seal over the metal with exterior-grade adhesives and sealants.
Patch old holes
Close unused holes with exterior-grade metal and sealant, not just a plug.
Shared utility chases and meter banks are common property. Seal where lines enter your unit inside, often in closets and under sinks, and report outside gaps to your building manager.
Materials
- Stainless steel or galvanized hardware cloth
- Exterior-grade metal patch
- Exterior-grade adhesives and sealants
- Gloves and flashlight
Safety notes
- Never open, unseal or work on the electric or gas meter itself. That belongs to the utility company.
- Don't pull on or damage service lines. If a line looks damaged, call the utility.
- Work around power lines only from the ground or a safely placed ladder well away from overhead service wires.
Before you seal the last gap
- Make sure nothing is still living inside. If mice are already in, set indoor snap traps along the walls as you seal, never as a substitute for sealing.
- Keep food, pet food and birdseed in sealed containers.
On a real house
Before photos from homes we’ve inspected, with the gap marked in highlighter.
BeforeUtility lines: where a pipe runs up into the soffit, the panel has broken away and left an open hole.
Want us to look at your house?Send photos from your walk-around and we'll send back a custom plan: each gap marked, what to seal it with, and in what order.
Mouse-proof my house