Rascally Rodents

Rodents, such as rats and house mice cause serious damage to structures of barndominiums, shop/houses and other buildings. These rascally rodents can cause grief with any structural system – not just post frame buildings. While rodents are notorious for their consumption and contamination of feed, rodent damage to insulation raises heating and cooling bills. Rodent-proof construction is your first and most important step on reducing rodent damage.

To prevent rodent entry, determine if a void is suitable for filling with caulk to stop airflow. If yes, use an appropriate caulk and backing to stop potential airflow through opening. Install a gnaw-resistant barrier over the gap to prevent entry. Recommended would be hardware cloth (wire mesh) 19 gauge. ½ x ½-inch mesh to exclude rats; 24-gauge, ¼ x ¼-inch to exclude mice. For openings less than ¾-inch wide unable to be secured by other means, tightly wedge copper or stainless steel wool into the gap.

Gaps or flaws often exist along building exteriors where wall framing meets foundations or slabs on grade. These gaps or flaws provide easy access to rodents. Rats can burrow beneath a concrete floor or shallow foundation wall. They frequently seek shelter under concrete floors and slabs, where they burrow to seek protection. Ideally install floors, slabs and sidewalks with curtain walls of ¼-inch mesh wire. Placing 18 inches of compacted sharp gravel under slab perimeters helps to discourage rodent burrowing as well.

Wire mesh should be galvanized or stainless steel for longevity and at a significantly lower cost than concrete ‘rat walls’.

Perimeter insulation is a necessary part of energy-efficient construction. Insulation around building exteriors, however, is subject to both mechanical damage and destruction by rodents. Besides wire-mesh protective coverings such as stucco, cement board, high-density fiberglass-reinforced plastics, or surface bonding products may also be used to protect rigid board insulation. Extend protective coverings or mesh at least 36 inches below finished grade, making sure no gaps are present at top or between covering members.

Concerned about burrowing rodents, or if your jurisdiction has a “rat wall” requirement? If so, investing in some wire mesh appears to be a cost effective prevention method.