Where building materials meet
Brick, block, stucco and sound siding already keep mice out. The weak spots are the seams where two materials meet.
Where to look
- Where stone or brick meets siding.
- Where a roof, porch or garage meets the wall of the house.
- Where trim meets a wall, and where boards only touch at the corners.
- Where a patio slab or step meets the house.
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
Two materials never fit perfectly, and they move differently with heat and moisture. Even a thin crack at that seam can be gnawed open into a mouse-sized hole, so we seal the seams, not just the obvious holes.
Common DIY mistake
Sealing for water only. A thin bead of caulk keeps rain out, but it won't stop gnawing. Mice open it back up.
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
Trace the seams
Walk the outside of the house and follow every line where one material meets another, from the foundation up to the roof.
Probe the gaps
Gently probe suspect seams. If a gap is about the width of your finger, or the material is soft or chewed, mark it.
Back the seam with metal
Press stainless steel or galvanized hardware cloth, or shaped exterior-grade metal, into or over the seam so there's metal behind the surface.
Seal over the metal
Seal it in with exterior-grade adhesives and sealants, and tool the surface smooth so there's no edge to grip.
Match the finish
Paint or finish over the seal if you like. The metal underneath is what does the work.
Seams between your unit and the next one, and where patios, balconies or garages meet the wall, are common spots. Exterior work usually needs your HOA's OK.
Materials
- Stainless steel or galvanized hardware cloth
- Exterior-grade metal flashing or trim
- Exterior-grade adhesives and sealants
- Caulking gun, putty knife, gloves
Safety notes
- Don't seal over weep holes or any opening built to drain water. See our weep holes guide.
- Check for wires or pipes before you fasten into a seam.
- Use a ladder safely for high seams, and leave roof-level work you can't reach safely to a pro.
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.
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