It is seldom possible to shut out rats completely from barns or
entirely to cut off their food supply where livestock is fed. Little
trouble will be experienced with them, however, if their harbors are
eliminated. In barns rat harbors are most frequently found around
stalls, under wooden mangers, and stall partitions, and beneath wooden
or dirt floors. In modern barns with concrete floors, concrete or metal
mangers, and metal stanchions, such places of retreat are entirely
eliminated. In older barns it is desirable at least to replace wooden
and dirt floors with concrete and reconstruct the mangers so that they
are a foot or more off the ground.
[Illustration: Figure 3.--Foundation and floor suitable for most types
of farm buildings]
Another common source of rat trouble, particularly in the northern half
of the United States, is the hollow wall, within which rats find safe
retreat and convenient runways leading to the haymow. In recent years
fibrous insulating materials have been used to line the interiors of
many farm buildings, and in most cases these have resulted in greatly
increased rat infestation. Rats cut through these composition boards
very easily and seem to be attracted by the facilities for breeding
thus provided. Hollow walls of any kind accessible to rats should
either be eliminated or adequately rat proofed. Such rat proofing may
be accomplished by filling the hollow spaces to a height of 8 or 10
inches above the sill with cement, bricks, or other material resistant
to the gnawing of rats, or a strip of galvanized metal 2 or more feet
wide may be carried around the inside wall just above the sill.
Old barns with wooden floors supported a few inches above the ground on
girders and posts are particularly objectionable from the standpoint
of rat infestation and should be rat proofed with concrete. (Fig. 4.)
A concrete foundation wall extending at least 2 feet below grade is
placed under the girder between the posts. The wooden posts may be
removed after the wall has hardened, and the spaces left should then be
filled in with concrete. A concrete floor is laid, and cement stucco on
metal lath is extended up the walls for at least 2 feet, preferably to
the level of window sills.
Rock foundations in many old barns offer excellent harborage for rats
unless pointed carefully with cement mortar. If possible, the floor
should be raised to the level of the sill and the walls plastered to
the window-sill level (fig. 5) in such manner as to prevent access by
rats to spaces between the studs.
The grain bin and other similar fixtures must always be considered in
rat proofing a barn. It is most important that they be so situated or
constructed that there shall be no hiding places for rats behind or
under them. The grain bin should be completely lined or covered with
metal and should have metal-clad lids. Any open spaces behind or under
the bins should be tightly closed with metal. (Fig. 6.)
[Illustration: Figure 4.--A, Detail of old barn with floor supported
a few inches above ground on girders and posts; B, same barn made rat
proof with concrete foundation and floors and cement-plastered walls]
[Illustration: Figure 5.--Method of rat proofing old stable, A.
Concreting and plastering as shown in B makes for better sanitary
conditions behind stock]
Other accessories of various kinds of barns should be examined
carefully and remodeled or moved if necessary to exclude rats or
eliminate harbors. The haymow frequently presents a difficult problem
in a heavily infested barn, but the haymow alone is seldom responsible
for the rats, for if all other rat harbors in the barn are effectively
eliminated or shut off, the rats will not long remain with the hay as
their only shelter. If the lower walls are of rough surface or composed
of open studs covered on the outside, rats can climb at the corners.
They may be prevented from doing so by the application of a strip of
metal 8 inches wide placed just below the joists of the upper floor.
Recommended construction of walls and floors in new frame barns is
shown in Figure 7.
[Illustration: Figure 6.--A convenient upper-story rat-proof grain bin]
[Illustration: Figure 7.--Recommended construction of walls and floors
of new frame barns. Cement plaster on metal lath or Insulating board is
applied to the inside of the studs at least to the level of the window
sills as a better protection against rats and as being more easily kept
clean than wooden lining]