108 PRINCIPLES OF POULTRY-HOUSE CONSTRUCTION 
Soil moisture has a tendency to work under the foundation 
and up through the floor, dampening the litter. This should be 
corrected by the construction of proper drains under the foundation 
when the house is built. A properly constructed concrete floor 
will keep out much soil moisture, as it is impervious to water. This 
is made with a layer of tar paper or tar paint beneath the finish 
coat of cement. 
Ventilation—The house should be well ventilated, without 
causing drafts to blow directly on the birds. An abundance of 
oxygen is essential if the birds are to perform their normal body 
functions. When a large number are continually crowded to- 
gether in close quarters during the entire winter, as is the case in 
most commercial laying houses, a large amount of fresh air is 
required. This can best be supplied by the use of muslin curtains 
in the front of the house, thus allowing at all times fresh air to 
pass in, and the moist, foul air to pass out. This change takes place 
without any drafts or rapid movements of air, the muslin acting 
as a sieve or buffer. In extremely cold sections, with birds not 
naturally suited to stand extremely low temperature, it is advis- 
able to have a second muslin curtain suspended in front of the 
roosting quarters to conserve the heat given off by their bodies at 
night. 
In the coldest climates special air shafts on the plan of King 
ventilators are sometimes used successfully instead of muslin cur- 
tains, or in combination with them. The out-take shaft is most 
essential. It may consist of a six-inch galvanized stove-pipe ex- 
tending from near the floor up through the highest point of the 
roof and projecting two feet or more above it. This pipe will be 
large enough for fifty fowls, and will take out the bad air and mois- 
ture if fresh air is allowed to enter through an in-take pipe or a 
small muslin curtain. 
A properly ventilated house will mean healthy birds, and less 
labor will be needed in keeping the house clean (Fig. 67). 
Plenty of Room for Exercise —Exercise is essential for the health 
of the birds, and to keep them from taking on too much surplus 
fat, which would be detrimental to heavy egg production. This 
latter purpose is important with the heavier breeds during the 
second and third year. Exercise can best be provided by the 
feeding of grain rations in deep litter on the floor. 
The number of birds which can safely be kept in a house of 
given dimensions will depend somewhat upon the breed and upon 
