Figure 3-5. Glue board.
b. Rat Proofing. Rat proofing consists of constructing buildings or of changing
their construction to prevent the entrance of rats and the eliminate potential shelter for
them within the structure of the building. It is obvious that rat proofing is of great
importance in the prevention and control of rats. Rats often gnaw wooden doors and
window frames to gain entrance into buildings; they can enlarge openings in masonry,
particularly in mortar and brick of poor quality. Openings of more than 3/4-inch width,
particularly those around pipes and wire conduits, should be closed. Conduits
themselves should be limited, if possible, to sizes that will prevent rodent passage.
Cracks around doors, gratings, windows, and other such openings, if less than 4 feet
above the ground or accessible from edges, pipes, or wires, should be covered or filled.
Doors should be self-closing and should fit tightly. Double walls and the space between
walls should be blocked with fire stops; these stops, as well as the beams supporting
floors, should be so constructed that they cannot be used by rats as runways. Wooden
sills and doors and windows at ground level should be sheathed with metal to prevent
gnawing. Sheet metal of at least 26-gauge, 1/4-inch and 1/2-inch hardware cloth, and
cement are all suitable rat proofing materials, although rats have been known to gnaw
fresh cement. Hardware cloth of 1/2-inch gauge will not stop the house mouse.
Foundations should extend at least 3 feet below the surface of the ground and have a 1-
foot offset extending outward from the building at the bottom to prevent burrowing (see
figure 3-6). In rat proofing, it should be remembered that rats can jump 2 feet vertically,
can dig 4 feet and occasionally even more to get under foundations, can climb rough
walls or smooth pipes of up to 3-inch diameter, and can travel on telephone and light
c. Harborage Elimination.
(1) Accumulations of trash and waste materials must be eliminated to
prevent their use as rat shelters. Likewise, salvage lumber and similar materials should
be stacked on platforms 18 inches above the ground and well away from the building
walls. The removal of vegetation along canal banks and near buildings will aid in