he basement floor. The value of
draining a building site when the building is first started is very
often overlooked. The cost of the drain will be saved in a few
years as the basement will be free from all excessive dampness. The
expense of installing a sub-soil after the building is up and in
use is great as well as inconvenient. The drain is called "sub-soil
drain" on account of its location under the ground and on account
of its duty of taking off all surplus water that is underground.
With the surface water taken off by the surface drains and the
sub-soil drained by the sub-soil drains, a wet building site can be
made practically dry (see Fig. 45).

MATERIALS USED IN SUB-SOIL CONSTRUCTION.--The object of the drain
is to collect water and carry it away from the building by means of
pipes. Terra-cotta pipes, with or without hubs, are used.
Perforated tile pipe is sometimes used. This pipe is unglazed
terra-cotta pipe with 1-inch holes in the sides about 3 or 4 inches
from the center. These holes allow the surplus water to enter the
bore of the pipe and thus be carried off beyond the building site.

When the sub-soil of a small building needs draining, the trenches
made for the house drain and its branches are used as a drain in
the following manner: The trenches are dug deeper than is required
for the house drain. The trenches are then filled to the correct
level with broken stones. There is space between these stones for
the water to find passage to a point away from the building. When
this method is employed, some provision must be made to prevent the
house drain from settling. When locating the drain, we must
consider approximately the amount of water that is likely to be in
the soil and required to be carried off. If there is considerable
water, the pipes should extend all around the outside of the
building foundation wall, also a main pipe running under the cellar
bottom with six branches, three branches on each side.

If there is not a great deal of surplus water in the soil, the
drain around the outside of the foundation wall should be put in
and one drain line running through the basement will be sufficient.

LAYING THE PIPE.--The drain pipe should be handled with care, for
it is easily broken. The trench should be laid out and dug, then
the pipe can be laid in it with a grade toward the outlet or
discharge. If pipes with a hub on one end are used, the hub should
not be cemented. A little oakum is packed