Can Rats Chew Through Anything? What Stops Them?

Rats are notorious for their ability to gnaw through tough materials. If you’ve ever dealt with a rat infestation, you’ve probably seen the damage they can cause.

Chewed wires, holes in walls, and gnawed pipes are all common signs of rat activity. This leads to an important question: can rats chew through anything?

No, rats can’t chew through everything, but they can chew through a surprising range of materials. Rats can gnaw through wood, plastic, drywall, soft metals, rubber, and even some types of concrete. However, they can’t chew through thick steel, solid stone, thick glass, or properly cured concrete.

Understanding what rats can and can’t chew through is really important when you’re trying to rat-proof your home. Using the wrong materials to seal entry points is basically a waste of time because rats will just chew right through them.

Why Rats Chew So Much

Rats don’t chew things just to cause problems (though it sure feels that way sometimes). They actually have to chew constantly because their teeth never stop growing.

A rat’s front teeth (incisors) grow about 4 to 5 inches per year. If they didn’t constantly wear them down by gnawing on things, their teeth would grow so long they couldn’t eat.

Chewing also helps rats explore their environment. They use their teeth kind of like we use our hands. They’ll chew on something to figure out what it’s made of, whether it’s edible, or if they can use it for nesting material.

When a rat wants to get somewhere, chewing is its main tool. If there’s food, water, or shelter on the other side of a barrier, the rat will chew through that barrier if it possibly can.

Materials Rats Can Chew Through

Here’s a list of common materials that rats can damage or chew through entirely.

Wood is one of the easiest materials for rats to chew. Soft woods like pine go really fast, but even hardwoods like oak will eventually give way. Rats can chew through a wooden door, wall stud, or floorboard if they’re determined enough.

Plastic is another material rats have no problem with. This includes PVC pipes, plastic storage containers, electrical wire insulation, and plastic sheeting. They’ll chew right through it.

Drywall (the material most interior walls are made of) is basically no obstacle at all. Rats can chew through drywall in less than an hour if they’re motivated.

Soft metals like aluminum, copper, and lead can be chewed through by rats. This is why they sometimes chew through aluminum siding, copper pipes, or lead flashing around chimneys.

Rubber and vinyl are easy targets too. This includes rubber hoses, weatherstripping, vinyl siding, and rubber seals around doors or windows.

Insulation of all types gets chewed up by rats. Fiberglass, foam board, spray foam (once it’s cured), and cellulose insulation are all things rats will tear apart for nesting material or to create pathways.

Cinder blocks and concrete blocks with large holes can be chewed through over time. The concrete itself is hard, but if it’s not very thick or if it’s old and crumbly, rats can make progress.

Materials Rats Can’t Chew Through

Now here’s the good news: there are materials rats can’t chew through, and these are what you should use when rat-proofing your home.

Thick steel is basically rat-proof. This includes steel sheets, steel mesh (hardware cloth), and steel wool. Rats’ teeth can’t make a dent in properly thick steel.

Solid concrete that’s been properly mixed and cured is too hard for rats to chew through. However, if the concrete is old, cracked, or poorly mixed, rats might be able to exploit weaknesses.

Thick glass is another material rats can’t damage. Windows, glass blocks, and thick glass panels are all safe from rat teeth.

Solid stone or brick (if it’s in good condition) can’t be chewed through. Rats might be able to exploit cracks or weak mortar between bricks, but they can’t chew through the stone itself.

Heavy-duty ceramic or tile is also rat-proof. The material is just too hard for their teeth to make any progress.

How Strong Are Rat Teeth?

Rat teeth are incredibly powerful. Their bite force is estimated at around 7,000 pounds per square inch. To put that in perspective, that’s stronger than a great white shark’s bite force relative to body size.

Rat teeth are also sharper than you might think. They have a chisel-like edge that’s constantly being sharpened as the rat chews. The front surface of the tooth is made of hard enamel, while the back is made of softer dentine. This means the back wears down faster, creating a sharp, beveled edge.

The teeth are also incredibly hard. They rank about 5.5 on the Mohs hardness scale (the scale geologists use to measure mineral hardness). That’s harder than steel, which is why rats can chew through metal.

On top of all this, rats have really strong jaw muscles. They can bite down repeatedly for hours without getting tired. This persistence is often more important than the strength of individual bites.

Can Rats Chew Through Walls?

Yes, rats can definitely chew through walls, especially if they’re made of drywall or wood. Most interior walls in homes are just drywall over wooden studs, and rats have no problem with either material.

If a rat is inside your walls and wants to get out, it can chew through the drywall into your room in less than an hour. You might hear the gnawing sound before you actually see the hole.

Exterior walls are usually tougher because they often have brick, stone, or thick siding on the outside. But if the wall has any wood or soft materials, rats can still chew through given enough time.

The wooden studs inside walls are particularly vulnerable. Rats will chew through studs to create pathways between rooms or to reach wiring and pipes.

If you hear scratching or chewing sounds inside your walls, you probably have rats creating tunnels or enlarging existing pathways. Don’t ignore this, because the damage will only get worse.

Can Rats Chew Through Concrete?

This depends on the type and quality of the concrete. Solid, properly cured concrete is too hard for rats to chew through. They’ll give up and look for an easier way in.

However, old concrete that’s cracking and crumbling is a different story. Rats can exploit these weaknesses and gradually widen cracks until they can squeeze through.

Concrete blocks (like cinder blocks) are also more vulnerable than solid concrete. The blocks have hollow spaces and are often not as dense as poured concrete. Rats can sometimes chew through the thin walls of these blocks.

If you’re using concrete to rat-proof your home, make sure it’s fresh and mixed properly. Hydraulic cement is a good option because it dries extremely hard and bonds well to existing concrete.

Can Rats Chew Through Metal?

Rats can chew through some metals, but not all. Soft metals like aluminum, copper, and lead are all vulnerable to rat teeth.

This is why you sometimes see rats that have chewed through aluminum window screens, copper pipes, or lead flashing on roofs. These metals are soft enough that persistent chewing can get through them.

However, rats can’t chew through hard metals like steel or iron. Steel mesh (hardware cloth), steel wool, and steel plates are all effective barriers against rats.

The thickness of the metal also matters. Even soft metals become harder to chew through when they’re really thick. A thin sheet of aluminum foil is easy, but a thick aluminum pipe will take much longer.

When you’re using metal to seal rat entry points, always use steel or another hard metal. Don’t rely on aluminum or copper because rats will eventually chew through it.

What About Electrical Wires?

Rats love chewing on electrical wires, and this is actually one of the most dangerous things they do. The plastic insulation around wires is easy for rats to chew through, and once they expose the copper wiring inside, they can cause serious problems.

Chewed wires can lead to short circuits, power outages, and even house fires. According to some estimates, rats cause thousands of house fires every year by damaging electrical wiring.

Rats are attracted to wires for a few reasons. The plastic coating smells interesting to them, the wires are the right texture for filing down their teeth, and wires are often located in areas where rats travel (inside walls, attics, and basements).

If you have rats in your home, one of the most important things to do is check your wiring regularly. Look for exposed copper, bite marks on the insulation, or areas where the wire coating has been completely stripped off.

You can protect wires by running them through metal conduit (metal pipes that hold electrical wires). This gives rats something hard to chew on instead of the wire itself, and they’ll usually give up and move on.

Can Rats Chew Through PVC Pipes?

Yes, rats can definitely chew through PVC pipes. PVC is a type of plastic, and plastic is one of the easier materials for rats to chew through.

This is a real problem in homes because PVC is commonly used for plumbing and drainage. If rats chew through a water pipe, you’ll end up with a leak. If they chew through a drain pipe, you might get sewage backup.

Rats are especially likely to chew on pipes if they’re trying to reach water. If they hear or smell water flowing through a pipe, they’ll chew through the plastic to get to it.

To protect PVC pipes, you can wrap them in steel mesh or run them through metal conduit. This gives the pipe an outer layer that rats can’t chew through.

If you’re installing new plumbing in an area where rats are a problem, consider using metal pipes instead of PVC. Copper and steel pipes are much more resistant to rat damage.

How Fast Can Rats Chew Through Materials?

The speed depends on the material and how determined the rat is. Here are some rough estimates.

Drywall can be chewed through in 30 minutes to an hour. It’s soft and crumbly, so rats make quick work of it.

Soft wood (like pine) might take a few hours to chew through a 2-inch thick piece. Harder woods take longer, maybe 12 to 24 hours of constant chewing.

Plastic varies depending on the thickness. Thin plastic sheeting can be chewed through in minutes. Thicker plastic like a storage container might take an hour or two.

Soft metals like aluminum can take several hours to a full day, depending on thickness. Rats will often give up on metal and look for easier materials first.

Expanding foam (the stuff you spray into cracks) can be chewed through in less than 30 minutes once it’s cured. It’s soft and easy to tear apart, which is why you should always use it with steel wool.

Signs Rats Are Chewing in Your Home

If you’re not sure whether you have rats, here are some signs to look for that indicate chewing activity.

Holes in walls, floors, or ceilings are the most obvious sign. These holes might start small but will get bigger over time as rats enlarge them.

Chewed wires or pipes show that rats are active in your walls or utility areas. Look for exposed copper wire or bite marks on plastic pipes.

Wood shavings or plastic pieces near baseboards, in corners, or under furniture indicate recent chewing. Rats will leave debris behind as they gnaw.

Gnaw marks on furniture, cardboard boxes, or food containers mean rats are looking for food or nesting materials. These marks look like small grooves or scratches made by teeth.

Grease marks along walls show where rats are traveling. As they move through tight spaces, their oily fur leaves dark smudges. If you see these marks plus holes nearby, rats are definitely chewing their way around.

Protecting Your Home from Rat Chewing

The key to preventing rat damage is using materials they can’t chew through when you’re sealing entry points.

Use steel wool to stuff into small holes and cracks. Rats hate chewing on it because it’s sharp and uncomfortable on their teeth and gums.

Use hardware cloth (steel mesh) to cover larger openings like vents, gaps under sheds, or holes in walls. Make sure the mesh has small holes (quarter-inch or less) so baby rats can’t squeeze through.

Use sheet metal to cover large areas that rats might chew on. You can attach it with screws to protect door edges, wall corners, or other vulnerable spots.

Use concrete or hydraulic cement to fill foundation cracks and holes in concrete. This creates a permanent, rat-proof barrier.

Avoid using caulk, spray foam (by itself), or wood to seal rat entry points. Rats will chew through these materials pretty easily, and you’ll just have to redo the work later.

Conclusion

Rats can chew through a wide range of materials including wood, plastic, drywall, soft metals, and rubber. However, they can’t chew through thick steel, solid concrete, thick glass, or stone.

Their incredibly strong teeth and persistent nature make them capable of damaging most common building materials. They chew constantly because their teeth never stop growing, and they’ll gnaw through barriers to reach food, water, or shelter.

When rat-proofing your home, always use materials rats can’t chew through. Steel wool, hardware cloth, sheet metal, and concrete are your best options. Avoid relying on wood, plastic, or foam alone because rats will eventually chew through them and get inside anyway.