How can the void between a wall and drywall be filled to keep mice out? - briefly
Seal the gap with a combination of steel‑wool filler and expanding polyurethane foam, then cover with a layer of cement‑based caulk to create a durable, rodent‑proof barrier. Ensure all penetrations are fully encased and the surface is smoothed for a seamless finish.
How can the void between a wall and drywall be filled to keep mice out? - in detail
Seal the space where the structural framing meets the interior sheathing with a material that rodents cannot gnaw through. Begin by locating all openings: gaps behind baseboards, around electrical boxes, and any cracks at the top of the wall cavity. Use a flashlight and a thin probe to confirm the size of each void.
- Clean the area. Remove dust, loose plaster, and any loose insulation. A vacuum or brush eliminates debris that could prevent adhesion.
- Apply a high‑density expanding polyurethane foam designed for pest control. Insert the nozzle into the gap, fill to the point where the foam expands and contacts both surfaces. Trim excess foam after it cures.
- For larger voids (greater than ¼ in), install a metal or copper mesh strip that spans the opening. Secure the mesh with construction adhesive, then cover with a thin layer of fire‑rated sealant.
- Where the mesh is not practical, use a cement‑based mortar or hydraulic cement. Mix according to manufacturer instructions, press into the cavity, and smooth the surface flush with the drywall.
- After the primary seal cures, reinforce with a silicone‑based caulk that remains flexible. Apply a continuous bead along the joint, smoothing with a fingertip or a caulking tool to eliminate air pockets.
- Replace any removed baseboards or trim, securing them with stainless‑steel nails to prevent future chewing.
Inspect the completed work periodically. Look for signs of new gnaw marks or fresh debris, and re‑apply sealant if minor cracks appear. Combining expanding foam, metal reinforcement, and flexible caulk creates a durable barrier that deters mice from exploiting the wall cavity.