Can Rats Chew Through Walls or Floors?

Rats gnaw through wood framing, drywall, plastic, vinyl, rubber, and aluminum sheeting with little difficulty — their incisors are harder than all of these materials and grow continuously, forcing regular use. Concrete is the honest exception: solid, properly cured concrete resists gnawing, which is why intact slab foundations are effective barriers. But rats exploit weakness rather than raw strength — they enlarge existing cracks, use brick weep holes and pipe penetrations, and can work through crumbling or low-quality concrete block. An Orkin Canada entomologist has noted that rats generally prefer to gnaw softer material over concrete, but cautioned that substandard cinder block may not stop a motivated rat.

The most serious risk from rats in walls isn't the chewed hole itself — it's electrical wiring. Rodents gnaw wire insulation to wear down their teeth, exposing conductors that can arc and ignite surrounding framing or insulation. The National Pest Management Association's own trade research puts rodents at 20–25% of fires with an undetermined cause, tied directly to their habit of chewing wiring and gas lines. We present this without fearmongering: most rat activity in a wall causes contamination, noise, and nuisance damage rather than a fire — but the pathway is real, and it's a legitimate reason to act on early signs rather than wait.

Because rats gnaw at edges, the fix is removing the bitable edge, not just patching the hole they made. Cap penetrations with mortar or metal rather than wood or foam, back gaps with hardware cloth, and repair cracked concrete instead of caulking over it. Scratching in walls, gnaw marks at baseboards, or grease rub marks along a wall cavity are signs worth acting on promptly.