Perimeter Drainage Systems
In our city, the greatest natural threat to the safety
of our possessions is winter rainfall and the flooding it brings. The principal
weapon to combat such problems is your home's perimeter
drainage system (sometimes called footing
drains).
Unfortunately, most houses built locally prior to the mid-1980's have antiquated
clay or concrete
tile systems, or, in the case of older homes,
sometimes no drainage at all.
Clay and concrete tile systems
are composed of 30cm (1') long sections of solid 4" diameter
vitreous clay or concrete pipe laid end-to-end with small gaps
between them to allow for water entry. Over time, however, tree
and shrub roots in search of water push their way under, between
and straight through the tiles, eventually forcing them out of
line or simply breaking them. This creates two primary problems:
· Increased
gaps allow for the intrusion of surrounding soil, which clogs
the tiles and further encourages root growth within
· With the tiles pushed out of line, there is no longer a consistent, downhill grade to direct water away
· With the tiles pushed out of line, there is no longer a consistent, downhill grade to direct water away
This problem is compounded by the fact that concrete
tile lacks the reinforcement of structural concrete (i.e. foundation or sidewalk)
and has an inherent tendency to dissolve over time in wet ground.
Modern drainage systems consist of continuous PVC
or ABS plastic pipe bedded in a layer of round drain rock. A complete drainage
system includes two separate runs of pipe:
· 4" perforated
pipe (footing
drain) at
the base of the foundation dedicated to picking up the ground water which
threatens to seep through the foundation
·3" or 4" solid pipe (rainwater lead) sitting above the perforated pipe to take away roof water being channeled into the system by way of the gutters and downspouts
·3" or 4" solid pipe (rainwater lead) sitting above the perforated pipe to take away roof water being channeled into the system by way of the gutters and downspouts
The two-pipe system ensures that extra rain water from
the roof is not being sent into pipes which are already working hard to take
water away from the foundation.
The two pipes combine past the low point of the foundation
into a solid pipe traveling off the property into the city's storm drain mains.
If the city's storm drain mains is sitting at a higher
elevation than the low point of the perimeter drainage system (an all too
common scenario in many areas of town), a sump
pump will
need to be installed.
It is possible (although it can sometimes create grade
challenges later on) to replace clay or concrete tile systems one section
at a time. Flexible couplings are available to connect new plastic pipe
to the old tile. Although the final cost of replacing the entire system
will be higher, the financial burden can in this way be spread out over
several years.
Homeowners whose drains are not working satisfactorily
will often attempt to bypass the problem by directing their downspouts
away from the house. It is important to remember that this water has to
end up somewhere. It will either find its way back through the soil to
the foundation, create washouts in the yard, or simply transfer the problem
to your unsuspecting neighbours.
Remember: In the city, it is NEVER an appropriate
solution to simply direct unwanted water out to the property line. This
is how law suits happen.
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<- Back To Start |
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1. Perimeter (House) Drainage |
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2. Yard Drainage |
| 3. Drainage System Maintenance | |
| 4. Drainage Photos | |
| 5. Services |
