Rats often enter homes and businesses due to the gnawing abilities of these rodents. Many property owners turn to materials like aluminum as a barrier, believing its metallic composition will provide adequate protection. The direct answer to whether a rat can chew through aluminum is frequently yes, especially given the soft, thin gauges of aluminum commonly used in construction and home repairs.
The Biological Imperative to Gnaw
Rats possess a remarkable set of four front teeth called incisors that are designed for constant, powerful gnawing. Unlike human teeth, a rat’s incisors never stop growing, potentially lengthening by several inches over a year if left unchecked. This continuous growth necessitates constant gnawing on hard objects to wear the teeth down and keep them at a functional length.
The enamel on a rat’s incisors is incredibly hard, ranking around 5.5 on the Mohs scale of mineral hardness, which is harder than iron and human tooth enamel. This hardness is partly due to a high iron content, which also gives the teeth their distinctive yellow-orange color. Their jaw muscles are powerful, capable of exerting an immense amount of force per square inch, allowing them to make rapid progress on various materials.
Aluminum’s Vulnerability as a Barrier
Aluminum is classified as a soft metal, which is a major factor in its vulnerability to rat incisors. The material’s malleability and relatively low tensile strength make it susceptible to the continuous, scraping action of a rat’s teeth. Thin sheets of aluminum, such as flashing, screen mesh, or the soft metal used in air duct tape, are easily breached by a determined rodent.
Rats do not need to bite through the entire thickness of the metal in a single attempt; they use their sharp incisors to shave away small fragments repeatedly. This process is particularly effective on aluminum, which does not resist the chiseling action of their teeth. The damage often begins where the metal is weakest, such as at an existing edge, a seam, or a corner that provides a starting point for the rat to gain purchase.
While very thick, structural aluminum would pose a significant challenge, the thin gauges typically used for exclusion work around a home are easily compromised. The goal for a rat is simply to create an opening large enough to squeeze through, which only needs to be about the size of a quarter.
Materials That Rats Cannot Penetrate
To establish a truly effective barrier against rats, materials harder than the rodent’s tooth enamel are necessary. Hardened steel is one of the few materials that rats cannot chew through because its hardness exceeds the capability of their incisors. This makes steel the preferred material for long-term rodent exclusion.
For sealing small gaps and crevices, coarse-grade stainless steel or copper mesh is highly effective. These materials cannot be gnawed through and are difficult for a rat to pull out of a hole once tightly packed. When covering larger openings, heavy-gauge hardware cloth, specifically 19-gauge or thicker, with a mesh size of one-half inch or less, provides a strong, durable barrier.
In foundational areas, solid concrete that has been properly mixed and cured will resist gnawing. For repairs or sealing larger access points, sheet metal of 24-gauge or thicker is recommended. Using these harder materials ensures that the barrier is a permanent physical obstruction that rats cannot penetrate to gain entry.