I often think about how blessed I am to have worked on older homes long
before I started building new homes. Frequently I would have to excavate next to
an old home if I were building a room addition or fixing its old foundation.
Often I would uncover the original draintile that rested against the footer
just below the foundation wall. The pipe was very unique as it was 12 inch long
four inch diameter orange vitrified clay pipe. The individual pieces were just
butted up against one another and a piece of thick roofing felt paper was placed
over the top of each of the joints.
Rest assured your builder is not going to install your drain tile in this
fashion. Newer products and installation methods are available that allow
builders to install foundation drainage systems that will work perfectly for
many years while providing you will tremendous peace of mind.
But many builders fail to realize that draintile systems can serve two
purposes. First and foremost they are supposed to collect water and pipe it to
another location where it can be transported away from the foundation. But some
new homes have shallow foundations that are just four or five feet below the
surface. These can often be found in houses with a walkout basement, those that
have a crawlspace and under most attached garages.
Draintiles installed next to the footers in these shallow foundations can be
used as water injection systems in times of drought. In fact, it is not a bad
idea to use draintiles systems in deeper foundations in houses with full
basements for the same thing.
The heavy clay soils found under many homes in the Midwest can shrink and
swell depending upon how much water they contain. In times of extended drought
some clay soils can shrink to such a degree that the foundation and footer can
fall. If the movement is uniform under all of the footers at the same time, then
a foundation may not sustain any damage. But this is highly unlikely.
Imagine if your builder were to extend several vertical pipes up from the
drain tile system to the grade level around your home. These pipes would connect
to the draintile piping with standard tee fittings. Placing a garden hose into
the vertical pipe would allow you to add water to the clay soil right where it
is most needed.
To maximize the benefits of this water injection system the draintile system
needs to be installed with care. If at all possible, try to make sure the piping
rests against the footer as opposed to resting on top of the footer. I prefer to
have one or two inches of coarse 1 inch or greater diameter washed rounded
gravel placed between the soil and the bottom of the drain pipe. If your builder
uses plastic draintile that has holes punched in it, these holes should point
down not up. If placed up, smaller pieces of gravel can clog the holes. What's
more, if the holes are up, it is very hard for the water to get into and out of
the pipe.
The draintile piping should be installed fairly level. It will still drain
water just fine if level as it is simply acting as a conduit for water movement.
Since water seeks its own level, the water trying to get away from the
foundation will flow out of the pipe or towards a basement sump pit with little
effort.
Installing the draintile nearly level is the best way when the piping will
function as a water injection system. As the water flows into the level piping
it travels rapidly to all parts of the system. This ensures that the clay soils
are wetted at or about the same time.
In times of drought you are simply trying to trick the soil around your
footers and foundation. Since the soil can't see the sky, it doesn't know if it
is raining or not. This soil simply wants to maintain a fairly constant moisture
content so that it doesn't move up or down. Your builder can give you this
ability with just a little bit of extra effort and material.