What should I use to seal a hole in the floor caused by mice?

What should I use to seal a hole in the floor caused by mice? - briefly

Fill the opening with steel wool or copper mesh, apply a rodent‑proof caulk, then cover with expanding foam or a concrete patch for a durable seal.

What should I use to seal a hole in the floor caused by mice? - in detail

Mice create openings that compromise structural integrity and allow further infestation. Effective repair requires a material that resists gnawing, adheres securely to the substrate, and fills the gap completely.

Recommended materials

  • Steel‑wool bundle, tightly packed into the void; rodents cannot chew through metal fibers.
  • Copper mesh, cut to size, acts as a reinforcing layer beneath sealant.
  • Polyurethane «expanding foam», injected to occupy irregular spaces, then trimmed flush.
  • Cement‑based floor patch, applied over a metal backing for permanent closure.
  • Epoxy wood filler, suitable for wooden subfloors when combined with a metal insert.

Repair procedure

  1. Remove loose debris and any remaining gnawed material.
  2. Insert a steel‑wool or copper mesh plug that fills the depth of the hole.
  3. Apply polyurethane «expanding foam» into remaining voids, allowing it to expand and cure according to manufacturer’s time‑frame.
  4. Trim excess foam level with the surrounding floor surface.
  5. Cover the repaired area with a cement‑based patch or epoxy filler, smoothing to match the existing floor.
  6. Allow the repair to cure fully before exposing the area to foot traffic.

Preventive measures

  • Seal entry points around baseboards, pipes, and vents with caulk or steel wool.
  • Install metal flashing at the perimeter of the repaired spot.
  • Maintain a clean environment to discourage rodent activity.

The combined use of a chew‑resistant core and a durable surface seal ensures long‑term closure of mouse‑damaged floor openings.