for your information: Slab
Leaks once detected,
be it through high water bills, dampness or wetness on the floor,
water coming through the foundation or the settling of the foundation,
must be found. Slab leaks occur in two
places, either the incoming water line or the sanitary sewer
line both of which are imbedded in the foundation of your home. (see Ground
Plumbing for more information) Both
types of leaks can cause a large amount of damage to the foundation
and each source of leaks has its own probable causes..
Slab
leaks in the incoming water line are often more destructive
as the water is under pressure, the main water line
from city runs
under the slab and comes up beside the water heater where branches
of copper piping go from one area of the house to another supplying
hot and cold water to each fixture...Pinhole leaks
can occur anywhere along this copper tubing which goes to every
fixture in your house. Some common causes are:
- Shifting of the foundation due
to poor design and installation, or drought, causing the
piping to move with it , pull apart and begin to leak ;
- Water Chemistry - If the water has a certain chemical combination
ie. high pH, high suspended solids, low organic matter, aluminum
bearing compounds, and free-chloride water, the addition
of a water softner can cause a leak in the pipes;
- Electrolysis - All metals
have stored energy, based on the energy it took to refine
the ore. When different metals come into contact and electric
current will flow between to equalize energy stored. If copper
pipes and the steel rebar are in contact the resulting electric
current will cause pinhole leaks in the copper pipes in your
foundation. ( see Corrosion
and Maggnesium Anodes for more information
on this subject )
- Water Velocity - If the the
water velocity orflow rate is too high for the copper piping
used, erosion can occur in the protective coating, creating
areas of bare uncoated copper, and a high rate of corrosion.
In addition leaks will form at any change of direction or
bend in the copper piping as a result of high water velocity.
- Poor Workmanship evidenced by excessive use of flex, poor
soldering, not reaming or kinking the copper can result in
leaks in your incoming water lines .
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here for more information on Detecting
Water Line Leaks |
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Slab
leaks in the sanitary sewer line only leak when one of
the fixtures in your home is used, like flushing a toilet
or running a faucet, some common causes are:
- Shifting of the Foundation - Cast
iron and PVC are brittle and will crack and brake with too
much shifting of the surrounding foundation
- Poor Workmanship- Pipes
need to be cut straight and true, as an angled cut will
not seal properly, each fitting must be secured to the
pipe properly with solvent weld, pushed all the way into
the fitting and held until the glue sets. Skipping any
step causes failure of the joint.
- Rust - When
piping is left in soil that is constantly wet, dissolved
minerals such as sulfate and chloride along with large
quantities of organic material will act upon the cast iron
or galvanized pipe causing breakdown and failure. PVC can
be immersed with no effect.
- Chemicals,
solvents, cleaning solutions which
we all put down our drains causes break down to occur
sooner in cast iron piping than in PVC piping.
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Any foundation leak can cause big trouble! Determining
the source of a slab leak is an educated techinal process of elimination.Your
foundation or slab is monolithic, meaning in one piece, and is all
tied together with rebar or steel to the beams
and piers before the concrete is poured. Imbedded in that concrete
is the preperatory ground
plumbing (click for details) which
includes all
the pipes that bring water to all your fixtures from the city water
system or your well and the sanitary lines that take the wastewater
out of your home from each fixture. If done properly, most foundations
have a fill layer of sand beneath them placed over the existing subsoil.
Water seeks the course of least resistance and the lowest spot, and
so the water leak travels in that sand layer away from the original
site of the leak making locating the source of the leak all the more
difficult. If one section of the foundation is compromised by a leak,
the whole foundation may be compromised. As the leak goes on undetected,
and more water is absorbed by the soil around and under the slab,
several dynamics can occur :
- Erosion: Where the leak literally
washes out the supporting soil
- Consolidation of localized pockets
of subsoil that produces differential movement
- Auto-compaction : the physical removal
of supporting contact between soft surface and slab
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