No Mice Here Mouse-proof my house
Entry point 6 of 8

Weep holes and the foundation line

Weep holes are small openings at the bottom of brick and stone walls that let water drain out. They need covering, not sealing.

Where to look

  • Weep holes along the bottom row of brick or stone, and above windows and doors.
  • The line where the foundation or slab meets the siding.
  • Cracks or gaps in the foundation, and where steps or patios meet the house.
  • Vents in the foundation or crawl space with damaged screens.

The rule of thumb: if a gap is about the width of your finger, a mouse can use it.

House illustration with the weep holes and the foundation line highlighted
Spot 6, marked in highlighter: weep holes and the foundation line.

Why mice use it

Weep holes and the foundation line are at ground level, right where mice run along the wall. An open weep hole leads into the hollow space behind the brick.

Common DIY mistake

Filling weep holes with mortar or caulk. They're there to let water out, so sealing them shut traps moisture in the wall.

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

  1. Find every weep hole

    Walk the base of every brick or stone wall, and check above windows and doors too.

  2. Cover, don't fill

    Fit stainless steel weep-hole covers or stainless steel mesh inserts that let water drain but block mice.

  3. Walk the foundation line

    Look for gaps where the foundation meets the siding, and where steps and patios meet the house.

  4. Seal foundation gaps with metal

    Close gaps with exterior-grade metal, or stainless steel or galvanized hardware cloth, sealed in with exterior-grade adhesives and sealants. Repair cracked masonry with a masonry patch.

  5. Fix vent screens

    Replace damaged foundation or crawl space vent screens with stainless steel or galvanized hardware cloth, fastened and sealed in.

The base of a shared building is usually common property. Report open weep holes and foundation gaps to your HOA or building manager.

Materials

  • Stainless steel weep-hole covers or mesh inserts
  • Stainless steel or galvanized hardware cloth
  • Exterior-grade metal
  • Exterior-grade adhesives and sealants
  • Masonry patch

Safety notes

  • Never seal weep holes shut. Moisture trapped in the wall causes rot and mold.
  • Keep crawl space and foundation vents open for airflow. Screen them, don't block them.
  • Call before you dig near the foundation, so you don't hit buried lines.

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.

  • Wooden lattice skirting along the base of a raised home, with wide openings into the dark crawlspace behind it. Before
    Foundation line: lattice skirting looks closed from the yard, but every opening leads straight into the crawlspace.
  • A long run of lattice skirting under a raised home, with gaps between the slats open to the crawlspace. Before
    Foundation line: gaps between the lattice slats run the whole length of the house.

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.

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