The following is for informational purposes only. Each situation can be different
By W. Tom Witherspoon, P.E.
All rights reserved by Foundation Repair Association and W. Tom Witherspoon,
P.E.
A study of failed foundations (ADSC 2000) estimates the cost of foundation
repair at over 12.5 billion dollars annually. The most common cause of
foundation failure/problems is poor maintenance, which can normally be
prevented. Considering that most remedial action will not completely keep a
foundation from moving, it becomes even more important that the homeowner
complies with the required maintenance procedures to reduce movement and allow
the house to function as originally intended. This is just as important after
repairs have been complete because the house may move in an area that has not
been repaired or is still dependent upon bearing soil stability for continued
performance. Since many foundation repair companies require homeowner
maintenance as a condition of their warranty agreement, compliance is also good
business and one of the best insurance policies available.
The following categories of maintenance are the most common problem areas and
should be addressed in a scheduled sequence to reduce movement before and after
foundation repairs to minimize distress in the foundation and the structure it
supports.
Slope Maintenance
The foundation should have been installed sufficiently above site grades to
allow proper post-construction surface drainage. It is the homeowner's
responsibility, however, to maintain these positive drainage conditions. The
primary function of good drainage is to prevent ponding near, or intrusion of
water, under the structure, which would increase seasonal moisture fluctuations,
or migration of water. Much of the damage caused by expansive soils is due to
lack of timely maintenance by the homeowner and is in some part preventable.
Under ideal conditions the slab will maintain its original position.
Unfortunately soil is not consistent and the moisture content is seldom at an
optimum level in the support soil when the slab is constructed. Many slabs are
poured on drier than normal soil that later becomes wet from capillary rise of
water from below, causing the thin floors to lift. After repeated drying and
rewetting of the support soil, small amounts of soil are squeezed from the
interface of the concrete base and the soil base to lower the wall into the
ground, much like a car tire miring into a rut. If the soil has a high amount of
clay con- tent, it will also deform under pressure, much like children's putty
during the swelling stage.
Earth Perimeters
The excavated area outside the foundation is usually filled with loose soil
fill when a house is constructed. This is usually called the "backfill area".
Maintaining a positive slope in the backfill area next to the house is the most
critical aspect of slope maintenance. During the first few months or years, this
material often settles. In many cases settlement is severe enough to reverse or
flatten the slope next to the foundation. Reverse or negative drainage will
cause ponding of water during precipitation or heavy irrigation. Ponding allows
an excessive amount of water to percolate into the ground" next to the
foundation, which may accelerate this settlement. To avoid this, the homeowner
should periodically com- pact the backfill area by tamping with a heavy piece of
wood such as a 4 "x 4 " . Hand compaction works best after a rain or snow melt
has dampened the ground or with the careful addition of small amounts of water
by the home- owner such as with a drip line. Additional soil should be added as
necessary to maintain a positive slope away from the foundation. This soil
should always be clay, not sand, so moisture can be better maintained and water
will run off instead of soaking in spotty high concentrations.
The minimum slope requirement should be 5% for the first 5' away from the
foundation (3" of drop) and then at a minimum discharge slope of 1%
(approximately 1/8" drop for every foot of distance) from that point on. The
type of vegetation may dictate a greater slope to avoid over saturation of the
critical perimeter soil. Some type of ground cover is recommended, however, to
reduce erosion and lower the frequency of slope maintenance work.
Flat Work
One of the beneficial functions of flat work {sidewalks and patios that are
not part of the foundation) adjacent to foundations is the prevention of
evapotranspiration and fluctuation of water intrusion to the bearing soils.
Therefore, every homeowner should conduct a yearly inspection of concrete flat
work and do any maintenance necessary to improve drainage and minimize
infiltration of water from rain, snow melt and lawn watering. This is especially
important during the first five years for a newly built house because this is
usually the time of most severe adjustment between the new construction and
environment. The process of inspection and maintenance should continue over the
years, but, cracking, settling and other problems should become less common.
Because perimeter fill material may not have been compacted in 4" lifts at
optimum moisture (as is normally recommended by engineers), settlement is
greater along the house. A negative slope may occur that will allow ponding.
This concentration of water wiII allow permeation through cracks in the concrete
and over- saturation of perimeter bearing soils. This deeper saturation will
often times cause damage to the foundation and/or basement floors. Because
evaporation is limited by the flat work, the ponded water may dramatically
increase moisture levels at the crucial perimeter beams and/or piers.
When this tilting of flat work occurs, the concrete should be replaced or
mudjacked to reverse the negative slope. If a minimum of 1 % slope (again about
1/8" for every foot of distance) is maintained, however, it will only be
necessary to seal all cracks and ports of entry to prevent vertical water
migration. This will include the perimeter joint around the foundation grade
beam. A urethane or other flexible sealant should be used that will allow some
movement but prevent water passing below the slab.
Flower Beds
Flatwork Settlement DiagramChanging the site by the addition of flower beds,
patios, fences, swimming pools, etc., may cause water ponding, which will
exacerbate the wet cycles. Therefore, proper drainage considerations during such
additions must be made.
Nurserymen will specify peat, bark, sandy loam and other planting substances,
which, in conjunction with bed borders, will increase moisture levels above that
desirable. Therefore, flower beds must have some provisions for elimination of
excess water. This may be in the form of weep holes, drain barriers or other
removal systems. The problems created by flower beds are not a popular subject
since homeowners will resist good engineering to beautify their house. There
should be a balance between vegetation utilized for aesthetic demands and
harming the bearing soils.
One of the primary problems in flower bed design is installation of a
concrete or steel barrier that will resist normalwater run-off. If these
barriers are desired, they should have openings cut to allow water passage and
avoid over-saturation.
Flower Beds Trapping Water DiagramThe use of highly permeable materials such
as peat, bark, etc., should only be used if topography allows installation of
subsurface drainage to collect excess water and discharge it away from the
foundation. This will also require installation of an impermeable barrier at the
bottom of the flower bed to help collect water for removal by the drain
medium.
Shrubs planted in the flower bed should be chosen for their compatibility to
the shallow barrier of the bed. Short and very contained root growth will be a
plus to proper health and maintenance of the bed vegetation.
In the flower bed, the slope should be a minimum of 5% (5/8" for every foot
of distance), unless ample subsurface drainage can be created to discharge water
away from the foundation.
Gutters And Downspouts
Gutters and Downspout DiagramGutters should be inspected twice a year, once
in the spring and again in the fall. All debris should be cleaned out and metal
gutters checked for rust. If there are trees near the roof, gutters may have to
be cleaned out more often.
Check the slope of the gutters, since poor slope causes water to accumulate
in low spots, building up debris and accelerating rusting. Slope of the gutters
should be a minimum of 1" of fall for each eight feet of length. The gutter can
be installed so that it drains in one direction. If, however, any single length
of gutter is more than 35' long it should be installed to drain both ways from
the center or have downspouts at a spacing of not more than 20' on center.
The easiest way to check the slope of a gutter is to use a garden hose or
pour a bucket of water into it and see if the water flows out smoothly or ponds
in low spots. The gutter should then be adjusted to remove any high or low spots
that prevent the smooth flow of water.
Downspouts should be checked for clogging at the same time the gutters are
checked. Clogging often occurs at the elbow where downspout and gutter meet. The
elbow can be removed for cleaning, but it may be necessary to use a plumber's
snake to clean the down- spout. If there is a problem with leaves, a leaf
strainer or leaf guard is a good buy as long as neither prevents proper function
of the gutter.
Splash blocks should be long enough and sloped enough to carryall water well
away from the foundation and beyond the backfill area. Water should be
discharged no closer than 5' from the foundation. Usually it is necessary to add
a downspout extension in order to get the water far away from the foundation. It
is possible to purchase extensions that have flexible elbows that can be bent up
to make it easier to mow the lawn. The extensions should be left down at all
times. Special roll-up type down- spout sheets (plastic tubes) that attach to
the end of the downspout are also available. These plastic tubes extend when
filled with water and roll up when empty. If erosion is a possibility, splash
blocks can be placed at the discharge point to prevent associated problems.
Because the materials delineated above are readily accessible at most
hardware and do-it- yourself stores in a variety of makes and colors, they can
add to the aesthetic qualities of a house.
Sub-Surface Drains
Subsurface drains will many times be utilized when topography, vegetation or
construction does not make it possible to drain at the surface. These may
consist of drain inlet basins, trench drains, funnel drains, etc. If correctly
installed, subsurface drains should require little maintenance. The most
important thing to remember is to avoid covering or obstructing the drain where
it discharges and to maintain adequate slope. It may occasionally be necessary
to clean out roots, nests or other debris from inlet basins or discharging ends
of the pipe.
Inlet basins should be inspected every 6 months to ensure these do not become
clogged with leaves, grass, soil or other debris, which would negate function.
The bottom of these inlets normally has a sedimentation basin that requires
removal of dirt as fill adds up over time. It may also be necessary to back wash
(main lines when discharge becomes a noticeable problem. If problems persist,
running of a( mechanical snake may be necessary to remove the obstruction.
Settlement problems in a yard will many I times crush piping and reduce the
discharge I flow, which will cause sedimentation to occur and subsequent closure
of the drain lines. Damage may also result from the driving of heavy trucks
across the surface. In any case, repair will normally require excavation and
replacement of the drain line. This may be an even greater possibility if clay
tile is used in lieu of heavy duty pvc.
Location of clean-outs and discharge lines will be a plus to locate problems
and initiate corrective action. Therefore, a drawing of lines and locations
should be made during installation for future reference.
Capillary/French Drains
French Drain DiagramCapillary drains are installed to intercept and collect
moving subsurface water and discharge it away from the structure. Unless the
slope allows, this will many times require installation of a deep sump and pump
to collect water and discharge it through a shallow drain line.
Sump Pump DiagramThe pumps utilized in this operation may malfunction and
unless an alarm system is installed there will be no warning. Therefore, it is
advisable that the homeowner inspect the sump at least every 6 months to make
sure trash, debris or pump failure has not occurred. If a solid sump well cover
is used, there will be less potential for debris, but the homeowner will not be
able to view the sump and determine if it is functioning. Therefore, the
addition of an alarm is recommended to provide a warning to the homeowner prior
to the onset of other problems, such as upheaval or water intrusion into the
structure.
Discharge lines should have clean-outs to allow removal of obstructions by
use of a snake or by jetting. Because effectiveness of these systems is largely
unknown until problems occur, it is wise to also backwash the system from the
discharge end and/or at the sump at lease every 2 years. The effectiveness of
this backwash will normally be seen by a discharge of debris, which may have
clogged the system.
Capillary drains are many times utilized as moisture barriers along the
perimeter of a foundation to shed water and stabilize sub slab moisture. This
will include extension of an impermeable barrier drain material under flower
pipe beds and up along French Drain grade beams. Therefore, it is important for
the home- owner to avoid any planting action that may puncture the barrier
material. If this damage occurs, it will be necessary to patch the hole with
materials that maintain the integrity of the barrier.
Irrigation/Sprinkler Systems
Watering of lawns and house perimeters must be regulated to maintain
consistent moisture content under the foundation. Therefore, allowances for
shrubs, plants and trees must be regulated for each segment of the yard. It is
advisable that watering along foundation perimeters should be on a maintenance
basis in corroboration with seasonal needs. This should be in conjunction with
plant and tree requirements so that added water will not be siphoned from under
the foundation.
Soil Shrinkage Due to Moisture Removal By Roots DiagramSeasonal monitoring
will necessitate different watering for the sides that receive added and hotter
sunlight (south and west sides), which increases evaporation. This monitoring
will also take into consideration time of day for watering. Most authorities
recommend early morning watering so that less evaporation will occur.
It must be understood that over watering can be just as damaging to the
foundation as under watering. If an electronic sprinkler system is installed,
each of the factors listed above must be incorporated into the sequence and
timing. Visual observations must also be included in the process to make
adjustments beyond the capacity of normal programming.
A variety of watering heads and systems are on the market that can be
customized to a homeowner's needs. There are bubble sprays, side sprays or angle
sprays that discharge from riser heads or pop-ups and can be mixed to provide
complete coverage. Where evaporation is a concern, however, a drip system will
provide necessary watering very efficiently. A close inspection of the ground
surface is necessary to ensure appropriate volumes and consistency. The goal is
to keep the soil near and under the foundation a consistent moisture (neither
wet and/or muddy nor dry and cracked).
An inspection of the sprinkler system should be performed at least twice a
year to determine if zones are functioning properly and if heads are improperly
discharging/broken or if leaks have occurred that will provide uneven watering.
This will, in the case of electronic watering systems, require running through
the system to determine if times, duration and frequency have been
maintained.
Vegetation And Trees
Studies from England and the United States have proven conclusively that
trees can cause damage to foundation stability and in more severe cases complete
foundation failure. Engineering studies map the effect of moisture withdrawal,
which can severely damage a slab- on-grade foundation and cause movement in a
pier and beam foundation system." Even when the perimeter of slab has been
underpinned, the interior slab will often deform as moisture migrates to the
perimeter as a result of root capillary action.
Planting of shrubs, flowers and trees should be with the understanding of
mature growth. Since additional moisture withdrawal will occur, distance and
watering patterns must be planned. If distance away from the foundation cannot
be maintained, root barriers may be necessary to reduce and/or eliminate
penetration under the slab and subsequent moisture withdrawal during times of
drought. The depth of this barrier may vary according to tree or plant root
expectations. These barriers, if properly constructed, can also serve as a
moisture barrier, which will add stability to moisture contents under the
foundation. Several agriculture agencies have material available which provides
projected root and moisture requirements for different types of vegetation.
Trees should not be planted closer to the foundation than approximately the
mature height of the tree. Some studies also indicate the tree limbs should not
invade the footprint of the house at maturity. There is a variance with
different types of trees that will necessitate their planting even further away.
If the proper distance cannot be maintained, it may be necessary to install a
root barrier to reduce the risk of future problems. Pruning of tree branches so
that they do not extend over the structure .can . also be an effective way to
limit root growth under the foundation.
The plants should fit the environment. In areas where droughts frequently
occur, it may be necessary to substitute drought resistant plants and trees to
incur less action on the foundation and provide easier maintenance of the
foliage.
Plumbing Leaks
Leaks in water and sewer lines will change the soil equilibrium under a
foundation and can lead to differential movement/damage. Therefore, it is
necessary to recognize signs that indicate problems exist.
If sewer lines are frequently stopped-up and roots are observed when
clean-out rooters are used, a sewer test should be conducted to determine the
presence and location of the break. Repair of a break should be made immediately
to avoid damage and future problems.
If abnormal- water bills indicate a sudden surge in water usage, wet spots
occur that can- not be explained or the owner should hear the sound of water
running in a bathroom (note: The bathroom nearest the water supply line will
provide the best indication of a water leak), a test of the pressure lines
should be conducted. If leaks are found, they should be repaired
immediately.
If hot spots occur in the floor or unexplained water should pool, it is a
good idea to call a plumber. Catching leaks early will many times avoid
extensive foundation damage that may be very difficult to repair.
Plumbing Leak Repairs
Leaks will often occur under a slab-on-grade foundation that require breakout
of a segment of the slab to gain entry and repair the plumbing. Care should be
taken to perform proper compaction of the soil when repairs have been completed.
This will require adequate moisture in the utilized soil and compaction of
layers no thicker than 3" to restore soil bearing to as it existed prior to
excavation. The vapor barrier should be repaired with plastic and a bonding
material to provide a vertical moisture stop from vertical capillary action or
water migration that may enter the living space.
Even in the case of post tensioned slabs, a minimum of #3 reinforcing steel
bars, at a spacing of 12" on center, should be utilized by drilling into the
existing slab horizontally and epoxying the reinforcing steel bars to provide
integrity. A bonding agent should be utilized at the edges to provide the
necessary bonded joint between existing and newly placed concrete. It is
normally advisable to install a moisture shield at the surface to prevent
migration of water through the concrete. This same procedure should be employed
if it was necessary to break through a grade beam to repair a plumbing line
except that non-shrink grout or epoxy concrete should be used to remold the
beam.
Reinforcing Steel Exposure
Many times concrete will blister or peel along the grade beam and reveal post
tensioning cable ends or conventional reinforcing steel bars. If left
unprotected, corrosion will slowly reduce the originally intended strength of
these reinforcing steel members. Therefore, it may be necessary to properly
clean the steel and remove all bond and then install an epoxy grout or
non-shrink grout to build back the beam and protect reinforcement. In more
severe situations, it may be necessary to drill and epoxy reinforcement dowels/
stirrups to build out the grade beam and provide adequate coverage of the
reinforcing steel.
Brick, Rock Or Cladding Cracks
Movement, weathering and freeze damage will often times create cracking in
the brick veneer or mortar that will allow passage of moisture into the
vulnerable wall material. Because this will often lead to deterioration of wood
members, it is advisable to seal these cracks with a urethane, mortar or caulk
that will prohibit weathering problems. Where obvious structural problems are
visible such a lateral displacement of veneer, lateral shields or other
retainers will be required to prevent additional movement damage.
Vent Covers
The original purpose of vent covers is to provide adequate circulation of air
under the floor of a pier and beam foundation so that moisture will not build up
and cause deterioration of wood members. Although coverage of these vents will
save money in reducing heating bills, it will often provide the unwanted
environment for wood rot. Therefore, it is not advised that these covers be
utilized unless other means of air circulation are available such as a sub floor
vent fan(s). Recent revelations of houses where the growth of bacteria was so
invasive and so deadly that the houses could not be salvaged, have led to anew
examination of detection and prevention of such growth.
Animal Damage
Dogs, skunks, armadillos, snakes etc. will many times burrow under a slab or
pier and beam foundation. This will undermine the bearing soil and may provide
entry for water that was not possible prior to the excavation. Therefore, it is
necessary to back fill the segment and/or place an impenetrable shield to
prevent further entry. It is also important to restore positive drainage to
prevent foundation moisture instability.
Termite Damage
Wood should not touch the ground at any place near a foundation. This will
only invite termites and provide avenues for their passage to more appetizing
segments of the structure. Therefore, the homeowner should take care to avoid
laying, placing or constructing wood that engages the ground. This includes
removal of any wood pieces that may exist in the crawl space of a pier and beam
foundation. When you add moisture to wood on the ground, you provide a perfect
environment for growth of termites and other wood eating insects.
Interior Doors
It is a known fact that most slab-on-grade foundations will move
differentially, which can cause misalignment of interior doors. Therefore, some
flexibility in the fit of the doors will reduce the inconvenience of this
movement.
Interior doors should have a minimum 1/8" to 3/16" clearance between the top
and side with the frame. This will allow some seasonal movement prior to
sticking. It is also a good idea to provide adequate clearance off the carpet or
floor to further buffer movement and allow for different heights of carpet
and/or flooring.
By W. Tom Witherspoon, P.E.
All rights reserved by Foundation Repair Association and W. Tom Witherspoon,
P.E.
A study of failed foundations (ADSC 2000) estimates the cost of foundation
repair at over 12.5 billion dollars annually. The most common cause of
foundation failure/problems is poor maintenance, which can normally be
prevented. Considering that most remedial action will not completely keep a
foundation from moving, it becomes even more important that the homeowner
complies with the required maintenance procedures to reduce movement and allow
the house to function as originally intended. This is just as important after
repairs have been complete because the house may move in an area that has not
been repaired or is still dependent upon bearing soil stability for continued
performance. Since many foundation repair companies require homeowner
maintenance as a condition of their warranty agreement, compliance is also good
business and one of the best insurance policies available.
The following categories of maintenance are the most common problem areas and
should be addressed in a scheduled sequence to reduce movement before and after
foundation repairs to minimize distress in the foundation and the structure it
supports.
Slope Maintenance
The foundation should have been installed sufficiently above site grades to
allow proper post-construction surface drainage. It is the homeowner's
responsibility, however, to maintain these positive drainage conditions. The
primary function of good drainage is to prevent ponding near, or intrusion of
water, under the structure, which would increase seasonal moisture fluctuations,
or migration of water. Much of the damage caused by expansive soils is due to
lack of timely maintenance by the homeowner and is in some part preventable.
Under ideal conditions the slab will maintain its original position.
Unfortunately soil is not consistent and the moisture content is seldom at an
optimum level in the support soil when the slab is constructed. Many slabs are
poured on drier than normal soil that later becomes wet from capillary rise of
water from below, causing the thin floors to lift. After repeated drying and
rewetting of the support soil, small amounts of soil are squeezed from the
interface of the concrete base and the soil base to lower the wall into the
ground, much like a car tire miring into a rut. If the soil has a high amount of
clay con- tent, it will also deform under pressure, much like children's putty
during the swelling stage.
Earth Perimeters
The excavated area outside the foundation is usually filled with loose soil
fill when a house is constructed. This is usually called the "backfill area".
Maintaining a positive slope in the backfill area next to the house is the most
critical aspect of slope maintenance. During the first few months or years, this
material often settles. In many cases settlement is severe enough to reverse or
flatten the slope next to the foundation. Reverse or negative drainage will
cause ponding of water during precipitation or heavy irrigation. Ponding allows
an excessive amount of water to percolate into the ground" next to the
foundation, which may accelerate this settlement. To avoid this, the homeowner
should periodically com- pact the backfill area by tamping with a heavy piece of
wood such as a 4 "x 4 " . Hand compaction works best after a rain or snow melt
has dampened the ground or with the careful addition of small amounts of water
by the home- owner such as with a drip line. Additional soil should be added as
necessary to maintain a positive slope away from the foundation. This soil
should always be clay, not sand, so moisture can be better maintained and water
will run off instead of soaking in spotty high concentrations.
The minimum slope requirement should be 5% for the first 5' away from the
foundation (3" of drop) and then at a minimum discharge slope of 1%
(approximately 1/8" drop for every foot of distance) from that point on. The
type of vegetation may dictate a greater slope to avoid over saturation of the
critical perimeter soil. Some type of ground cover is recommended, however, to
reduce erosion and lower the frequency of slope maintenance work.
Flat Work
One of the beneficial functions of flat work {sidewalks and patios that are
not part of the foundation) adjacent to foundations is the prevention of
evapotranspiration and fluctuation of water intrusion to the bearing soils.
Therefore, every homeowner should conduct a yearly inspection of concrete flat
work and do any maintenance necessary to improve drainage and minimize
infiltration of water from rain, snow melt and lawn watering. This is especially
important during the first five years for a newly built house because this is
usually the time of most severe adjustment between the new construction and
environment. The process of inspection and maintenance should continue over the
years, but, cracking, settling and other problems should become less common.
Because perimeter fill material may not have been compacted in 4" lifts at
optimum moisture (as is normally recommended by engineers), settlement is
greater along the house. A negative slope may occur that will allow ponding.
This concentration of water wiII allow permeation through cracks in the concrete
and over- saturation of perimeter bearing soils. This deeper saturation will
often times cause damage to the foundation and/or basement floors. Because
evaporation is limited by the flat work, the ponded water may dramatically
increase moisture levels at the crucial perimeter beams and/or piers.
When this tilting of flat work occurs, the concrete should be replaced or
mudjacked to reverse the negative slope. If a minimum of 1 % slope (again about
1/8" for every foot of distance) is maintained, however, it will only be
necessary to seal all cracks and ports of entry to prevent vertical water
migration. This will include the perimeter joint around the foundation grade
beam. A urethane or other flexible sealant should be used that will allow some
movement but prevent water passing below the slab.
Flower Beds
Flatwork Settlement DiagramChanging the site by the addition of flower beds,
patios, fences, swimming pools, etc., may cause water ponding, which will
exacerbate the wet cycles. Therefore, proper drainage considerations during such
additions must be made.
Nurserymen will specify peat, bark, sandy loam and other planting substances,
which, in conjunction with bed borders, will increase moisture levels above that
desirable. Therefore, flower beds must have some provisions for elimination of
excess water. This may be in the form of weep holes, drain barriers or other
removal systems. The problems created by flower beds are not a popular subject
since homeowners will resist good engineering to beautify their house. There
should be a balance between vegetation utilized for aesthetic demands and
harming the bearing soils.
One of the primary problems in flower bed design is installation of a
concrete or steel barrier that will resist normalwater run-off. If these
barriers are desired, they should have openings cut to allow water passage and
avoid over-saturation.
Flower Beds Trapping Water DiagramThe use of highly permeable materials such
as peat, bark, etc., should only be used if topography allows installation of
subsurface drainage to collect excess water and discharge it away from the
foundation. This will also require installation of an impermeable barrier at the
bottom of the flower bed to help collect water for removal by the drain
medium.
Shrubs planted in the flower bed should be chosen for their compatibility to
the shallow barrier of the bed. Short and very contained root growth will be a
plus to proper health and maintenance of the bed vegetation.
In the flower bed, the slope should be a minimum of 5% (5/8" for every foot
of distance), unless ample subsurface drainage can be created to discharge water
away from the foundation.
Gutters And Downspouts
Gutters and Downspout DiagramGutters should be inspected twice a year, once
in the spring and again in the fall. All debris should be cleaned out and metal
gutters checked for rust. If there are trees near the roof, gutters may have to
be cleaned out more often.
Check the slope of the gutters, since poor slope causes water to accumulate
in low spots, building up debris and accelerating rusting. Slope of the gutters
should be a minimum of 1" of fall for each eight feet of length. The gutter can
be installed so that it drains in one direction. If, however, any single length
of gutter is more than 35' long it should be installed to drain both ways from
the center or have downspouts at a spacing of not more than 20' on center.
The easiest way to check the slope of a gutter is to use a garden hose or
pour a bucket of water into it and see if the water flows out smoothly or ponds
in low spots. The gutter should then be adjusted to remove any high or low spots
that prevent the smooth flow of water.
Downspouts should be checked for clogging at the same time the gutters are
checked. Clogging often occurs at the elbow where downspout and gutter meet. The
elbow can be removed for cleaning, but it may be necessary to use a plumber's
snake to clean the down- spout. If there is a problem with leaves, a leaf
strainer or leaf guard is a good buy as long as neither prevents proper function
of the gutter.
Splash blocks should be long enough and sloped enough to carryall water well
away from the foundation and beyond the backfill area. Water should be
discharged no closer than 5' from the foundation. Usually it is necessary to add
a downspout extension in order to get the water far away from the foundation. It
is possible to purchase extensions that have flexible elbows that can be bent up
to make it easier to mow the lawn. The extensions should be left down at all
times. Special roll-up type down- spout sheets (plastic tubes) that attach to
the end of the downspout are also available. These plastic tubes extend when
filled with water and roll up when empty. If erosion is a possibility, splash
blocks can be placed at the discharge point to prevent associated problems.
Because the materials delineated above are readily accessible at most
hardware and do-it- yourself stores in a variety of makes and colors, they can
add to the aesthetic qualities of a house.
Sub-Surface Drains
Subsurface drains will many times be utilized when topography, vegetation or
construction does not make it possible to drain at the surface. These may
consist of drain inlet basins, trench drains, funnel drains, etc. If correctly
installed, subsurface drains should require little maintenance. The most
important thing to remember is to avoid covering or obstructing the drain where
it discharges and to maintain adequate slope. It may occasionally be necessary
to clean out roots, nests or other debris from inlet basins or discharging ends
of the pipe.
Inlet basins should be inspected every 6 months to ensure these do not become
clogged with leaves, grass, soil or other debris, which would negate function.
The bottom of these inlets normally has a sedimentation basin that requires
removal of dirt as fill adds up over time. It may also be necessary to back wash
(main lines when discharge becomes a noticeable problem. If problems persist,
running of a( mechanical snake may be necessary to remove the obstruction.
Settlement problems in a yard will many I times crush piping and reduce the
discharge I flow, which will cause sedimentation to occur and subsequent closure
of the drain lines. Damage may also result from the driving of heavy trucks
across the surface. In any case, repair will normally require excavation and
replacement of the drain line. This may be an even greater possibility if clay
tile is used in lieu of heavy duty pvc.
Location of clean-outs and discharge lines will be a plus to locate problems
and initiate corrective action. Therefore, a drawing of lines and locations
should be made during installation for future reference.
Capillary/French Drains
French Drain DiagramCapillary drains are installed to intercept and collect
moving subsurface water and discharge it away from the structure. Unless the
slope allows, this will many times require installation of a deep sump and pump
to collect water and discharge it through a shallow drain line.
Sump Pump DiagramThe pumps utilized in this operation may malfunction and
unless an alarm system is installed there will be no warning. Therefore, it is
advisable that the homeowner inspect the sump at least every 6 months to make
sure trash, debris or pump failure has not occurred. If a solid sump well cover
is used, there will be less potential for debris, but the homeowner will not be
able to view the sump and determine if it is functioning. Therefore, the
addition of an alarm is recommended to provide a warning to the homeowner prior
to the onset of other problems, such as upheaval or water intrusion into the
structure.
Discharge lines should have clean-outs to allow removal of obstructions by
use of a snake or by jetting. Because effectiveness of these systems is largely
unknown until problems occur, it is wise to also backwash the system from the
discharge end and/or at the sump at lease every 2 years. The effectiveness of
this backwash will normally be seen by a discharge of debris, which may have
clogged the system.
Capillary drains are many times utilized as moisture barriers along the
perimeter of a foundation to shed water and stabilize sub slab moisture. This
will include extension of an impermeable barrier drain material under flower
pipe beds and up along French Drain grade beams. Therefore, it is important for
the home- owner to avoid any planting action that may puncture the barrier
material. If this damage occurs, it will be necessary to patch the hole with
materials that maintain the integrity of the barrier.
Irrigation/Sprinkler Systems
Watering of lawns and house perimeters must be regulated to maintain
consistent moisture content under the foundation. Therefore, allowances for
shrubs, plants and trees must be regulated for each segment of the yard. It is
advisable that watering along foundation perimeters should be on a maintenance
basis in corroboration with seasonal needs. This should be in conjunction with
plant and tree requirements so that added water will not be siphoned from under
the foundation.
Soil Shrinkage Due to Moisture Removal By Roots DiagramSeasonal monitoring
will necessitate different watering for the sides that receive added and hotter
sunlight (south and west sides), which increases evaporation. This monitoring
will also take into consideration time of day for watering. Most authorities
recommend early morning watering so that less evaporation will occur.
It must be understood that over watering can be just as damaging to the
foundation as under watering. If an electronic sprinkler system is installed,
each of the factors listed above must be incorporated into the sequence and
timing. Visual observations must also be included in the process to make
adjustments beyond the capacity of normal programming.
A variety of watering heads and systems are on the market that can be
customized to a homeowner's needs. There are bubble sprays, side sprays or angle
sprays that discharge from riser heads or pop-ups and can be mixed to provide
complete coverage. Where evaporation is a concern, however, a drip system will
provide necessary watering very efficiently. A close inspection of the ground
surface is necessary to ensure appropriate volumes and consistency. The goal is
to keep the soil near and under the foundation a consistent moisture (neither
wet and/or muddy nor dry and cracked).
An inspection of the sprinkler system should be performed at least twice a
year to determine if zones are functioning properly and if heads are improperly
discharging/broken or if leaks have occurred that will provide uneven watering.
This will, in the case of electronic watering systems, require running through
the system to determine if times, duration and frequency have been
maintained.
Vegetation And Trees
Studies from England and the United States have proven conclusively that
trees can cause damage to foundation stability and in more severe cases complete
foundation failure. Engineering studies map the effect of moisture withdrawal,
which can severely damage a slab- on-grade foundation and cause movement in a
pier and beam foundation system." Even when the perimeter of slab has been
underpinned, the interior slab will often deform as moisture migrates to the
perimeter as a result of root capillary action.
Planting of shrubs, flowers and trees should be with the understanding of
mature growth. Since additional moisture withdrawal will occur, distance and
watering patterns must be planned. If distance away from the foundation cannot
be maintained, root barriers may be necessary to reduce and/or eliminate
penetration under the slab and subsequent moisture withdrawal during times of
drought. The depth of this barrier may vary according to tree or plant root
expectations. These barriers, if properly constructed, can also serve as a
moisture barrier, which will add stability to moisture contents under the
foundation. Several agriculture agencies have material available which provides
projected root and moisture requirements for different types of vegetation.
Trees should not be planted closer to the foundation than approximately the
mature height of the tree. Some studies also indicate the tree limbs should not
invade the footprint of the house at maturity. There is a variance with
different types of trees that will necessitate their planting even further away.
If the proper distance cannot be maintained, it may be necessary to install a
root barrier to reduce the risk of future problems. Pruning of tree branches so
that they do not extend over the structure .can . also be an effective way to
limit root growth under the foundation.
The plants should fit the environment. In areas where droughts frequently
occur, it may be necessary to substitute drought resistant plants and trees to
incur less action on the foundation and provide easier maintenance of the
foliage.
Plumbing Leaks
Leaks in water and sewer lines will change the soil equilibrium under a
foundation and can lead to differential movement/damage. Therefore, it is
necessary to recognize signs that indicate problems exist.
If sewer lines are frequently stopped-up and roots are observed when
clean-out rooters are used, a sewer test should be conducted to determine the
presence and location of the break. Repair of a break should be made immediately
to avoid damage and future problems.
If abnormal- water bills indicate a sudden surge in water usage, wet spots
occur that can- not be explained or the owner should hear the sound of water
running in a bathroom (note: The bathroom nearest the water supply line will
provide the best indication of a water leak), a test of the pressure lines
should be conducted. If leaks are found, they should be repaired
immediately.
If hot spots occur in the floor or unexplained water should pool, it is a
good idea to call a plumber. Catching leaks early will many times avoid
extensive foundation damage that may be very difficult to repair.
Plumbing Leak Repairs
Leaks will often occur under a slab-on-grade foundation that require breakout
of a segment of the slab to gain entry and repair the plumbing. Care should be
taken to perform proper compaction of the soil when repairs have been completed.
This will require adequate moisture in the utilized soil and compaction of
layers no thicker than 3" to restore soil bearing to as it existed prior to
excavation. The vapor barrier should be repaired with plastic and a bonding
material to provide a vertical moisture stop from vertical capillary action or
water migration that may enter the living space.
Even in the case of post tensioned slabs, a minimum of #3 reinforcing steel
bars, at a spacing of 12" on center, should be utilized by drilling into the
existing slab horizontally and epoxying the reinforcing steel bars to provide
integrity. A bonding agent should be utilized at the edges to provide the
necessary bonded joint between existing and newly placed concrete. It is
normally advisable to install a moisture shield at the surface to prevent
migration of water through the concrete. This same procedure should be employed
if it was necessary to break through a grade beam to repair a plumbing line
except that non-shrink grout or epoxy concrete should be used to remold the
beam.
Reinforcing Steel Exposure
Many times concrete will blister or peel along the grade beam and reveal post
tensioning cable ends or conventional reinforcing steel bars. If left
unprotected, corrosion will slowly reduce the originally intended strength of
these reinforcing steel members. Therefore, it may be necessary to properly
clean the steel and remove all bond and then install an epoxy grout or
non-shrink grout to build back the beam and protect reinforcement. In more
severe situations, it may be necessary to drill and epoxy reinforcement dowels/
stirrups to build out the grade beam and provide adequate coverage of the
reinforcing steel.
Brick, Rock Or Cladding Cracks
Movement, weathering and freeze damage will often times create cracking in
the brick veneer or mortar that will allow passage of moisture into the
vulnerable wall material. Because this will often lead to deterioration of wood
members, it is advisable to seal these cracks with a urethane, mortar or caulk
that will prohibit weathering problems. Where obvious structural problems are
visible such a lateral displacement of veneer, lateral shields or other
retainers will be required to prevent additional movement damage.
Vent Covers
The original purpose of vent covers is to provide adequate circulation of air
under the floor of a pier and beam foundation so that moisture will not build up
and cause deterioration of wood members. Although coverage of these vents will
save money in reducing heating bills, it will often provide the unwanted
environment for wood rot. Therefore, it is not advised that these covers be
utilized unless other means of air circulation are available such as a sub floor
vent fan(s). Recent revelations of houses where the growth of bacteria was so
invasive and so deadly that the houses could not be salvaged, have led to anew
examination of detection and prevention of such growth.
Animal Damage
Dogs, skunks, armadillos, snakes etc. will many times burrow under a slab or
pier and beam foundation. This will undermine the bearing soil and may provide
entry for water that was not possible prior to the excavation. Therefore, it is
necessary to back fill the segment and/or place an impenetrable shield to
prevent further entry. It is also important to restore positive drainage to
prevent foundation moisture instability.
Termite Damage
Wood should not touch the ground at any place near a foundation. This will
only invite termites and provide avenues for their passage to more appetizing
segments of the structure. Therefore, the homeowner should take care to avoid
laying, placing or constructing wood that engages the ground. This includes
removal of any wood pieces that may exist in the crawl space of a pier and beam
foundation. When you add moisture to wood on the ground, you provide a perfect
environment for growth of termites and other wood eating insects.
Interior Doors
It is a known fact that most slab-on-grade foundations will move
differentially, which can cause misalignment of interior doors. Therefore, some
flexibility in the fit of the doors will reduce the inconvenience of this
movement.
Interior doors should have a minimum 1/8" to 3/16" clearance between the top
and side with the frame. This will allow some seasonal movement prior to
sticking. It is also a good idea to provide adequate clearance off the carpet or
floor to further buffer movement and allow for different heights of carpet
and/or flooring.
