What should be poured under the floor to deter mice?

What should be poured under the floor to deter mice? - briefly

Apply a rodent‑repellent sealant—silicone or polyurethane caulk mixed with a deterrent such as peppermint oil, copper sulfate, or a mild rodenticide—along the entire subfloor perimeter. This creates a continuous chemical and physical barrier that mice cannot cross.

What should be poured under the floor to deter mice? - in detail

Applying a liquid barrier beneath a floor is one of the most reliable methods to block mouse entry. The most effective options are:

  • Poured concrete – a continuous slab of cement mortar creates a solid, impermeable base that eliminates gaps and cracks. Use a mix with a minimum compressive strength of 3000 psi; add a water‑reducing admixture to improve flow and reduce shrinkage. Finish the surface smooth to prevent mouse burrowing.

  • Epoxy resin coating – a two‑part epoxy poured over the subfloor cures into a hard, seamless membrane. Choose a formulation with a high solids content (≥70 %) for maximum thickness. Epoxy adheres well to concrete, wood, or metal substrates and resists chewing.

  • Polyurethane floor sealant – a poured‑in‑place polyurethane creates a flexible, waterproof layer that remains intact under slight movement. Select a product rated for floor applications and apply a minimum of 2 mm thickness.

  • Silicone‑based sealant – a low‑viscosity silicone can be poured into seams and joints before the final floor covering is installed. It cures into a rubbery, non‑porous barrier that mice cannot penetrate.

  • Rodent‑repellent polymer slurry – commercial products combine a polymer base with natural repellents (e.g., peppermint oil, capsaicin). The slurry is poured into crawl spaces, forming a thin film that is both a physical block and a chemical deterrent.

Implementation steps:

  1. Inspect and clean the area, removing debris, old caulking, and any existing mouse pathways.
  2. Seal macro‑cracks with hydraulic cement or expanding foam before pouring the main barrier.
  3. Mix the chosen material according to manufacturer specifications, ensuring consistent viscosity for even flow.
  4. Pour the liquid evenly, using a screed or roller to distribute it across the entire under‑floor surface.
  5. Allow the barrier to cure fully—concrete typically requires 24–48 hours, epoxy and polyurethane need 4–6 hours for tack‑free finish and 24 hours to reach full strength.
  6. Inspect for pinholes or voids after curing; fill any defects with the same material before installing the final flooring.

When applied correctly, a poured barrier eliminates the structural openings that mice exploit, providing long‑term protection without reliance on traps or poisons.