Can Rats Dig Through the Pipe System Under a House & Chew Through a Concrete Floor?

Common Rats

• A few species of non-native rat plague homeowners. The cotton rat is the smallest at 5 to 7 inches in length. It is gray with rough black guard hairs. The wood rat is also sometimes known as the pack rat and is grayish brown with light-colored feet and a light-colored underbelly. The roof rat is slender and around 7 to 8 inches in length. It is typically grayish black. The Norway rat is the largest of the rats commonly infesting homes and urban structures. It is around 8 to 10 inches long and is grayish brown.

Rat Teeth

• A rat's teeth are very strong and, according to the Washington Department of Fish and Wildlife, they grow about 5 inches every year. To keep their teeth at a manageable size, rats need to continually gnaw at hard objects. A rat's front incisors curve inward, which makes chewing on smooth surfaces difficult. They can, however, chew on anything rough like concrete, cinder block, plastic, rubber, metal screens or wood. If given an edge to start chewing on, they can chew through smooth surfaces like lead or aluminum sheeting.

Access Points

• With the exception of the roof rat, most species burrow underground or build their nests low to the ground. It is probably possible for a rat to burrow into a home from underground and through the concrete slab, but there are likely access points that require less effort. Rats will often chew through wooden siding or slip through loose-fitting doors or window screens. Other common access points include openings where cables or pipes enter structures, vents or any opening or crack larger than a half inch. Norway rats and roof rats are strong swimmers and commonly enter buildings through sewer lines, emerging from toilets or drains.

Exclusion

• Since rats can chew through almost anything, excluding them from a structure can be difficult. Seal around all wires and pipes entering a building with sheet metal or animal screening. Animal screening can be effective for vents, like bathroom vents, as well. Door flashing installed at the bottom of all exterior doors can help keep rats from chewing through the wood. Ensure all interior drains have covers and install one-way traps for toilets if necessary. Check your roofline for any openings that might allow roof rats entry to your home, and seal them with animal screening or sheet metal flashing.