FOUNDATION the items which affect the foundation are trees or large shrubs close to the structure, excessively wet soil, dry soil, broken water or sewer pipe next to or beneath the home, erosion of soil.
Unequal foundation movement results In cupping when moist clay expands and downwarping when expansive clay dries and shrinks around slab-on·grade foundations.
CUPPING excessive moisture can cause perimeter to heave.
PROBLEM:
- Cracks In exterior masonry.
- Horizontal and vertical separation of windows from adjacent masonry or siding: general distortion of door and window frames and sticking of doors and windows.
- Cracks and spalllng at comers of foundation slab.
- Horizontal cracks at Joint between foundation slab and masonry.
- Interior partitions separate from ceiling and, occasionally, from floor.
DOWNWARPING excessive dry soil can cause foundation to settle
PROBLEM:
- Cracks In exterior masonry.
- Horizontal and vertical separation of windows and doors from adJacent masonry or siding; general distortion of door and window frames and sticking of doors ancL windows.
- Break In slab, noticeable In Interior of house In some cases.
- Noticeable tilt of exterior walls In some cases.
- Cracking of Interior gypsum board ceilings and partitions, particUlarly at door and window corners (Not shown)
MAINTENANCE OF SLAB ON-GROUND FOUNDATIONS
Foundation problems associated with expansive clay are usually caused by the lack of moisture in the soil which shrinks when dry and results in foundation deflections and settlements. When the moisture content of the active supporting soil at the perimeter of the foundation is maintained uniformly, the changes of foundation failure are greatly alleviated.
Before any foundation maintenance can be effectively implemented, it is imperative that proper drainage is provided. This could necessitate some recontouring of existing grade, placing fill dirt at perimeter grade beams, placing splash blocks at downspouts to prevent soil erosion and other specifics peculiar to a particular site. Water should be always run away from the house and there should be no ponding of water near the foundation. Care should be taken to insure that soil is from one to two inches below the top of the perimeter grade beams. The soil should be sloped approximately one inch per foot to drain at least eighteen (18) inches from the perimeter of the foundation.
The moisture content of the soil at the perimeter of the foundation should be slowly increased and maintained during all seasons. This is best accomplished by placing soaker hoses eighteen (18) inches from the foundation and regulated to a flow of onefourth (1/4) inch in height until the water is observed standing on the ground. The volumetric expansion of the active soil will now provide uniform support for the foundation. Watering should be repeated when drying cracks are observed or when the soil is evidently dried.
Trees and shrubbery can produce an adverse effect on the foundation. Their roots sap moisture from the soil, both at the perimeter and under the slab. This lowers the moisture from the soil, both at the perimeter and under the slab. This lowers the moisture content of the active supporting soil at various places which can cause differential movements of the foundation. In certain instances, root severing at the foundation may be recommended.
Guttering is not necessary where proper drainage is provided. On gabled ends or sides of the house, there is no run-off so more watering will probably be required. During hot and dry seasons, the South and West sides may require more watering than the North and East sides, which shaded and not exposed to as much direct sun.
Most major foundation movements can be prevented if the active supporting soil is well maintained. The extent of distress transmitted to the structure would be lessened and the service life of the residence would be considerably increased.
WATERING TO PROTECT YOUR FOUNDATION
You need to keep the ground close to the foundation moist all year long. Sprinklers next to the foundation will make your job a lot easier. Here are some suggestions:
- Always keep soil damp out three feet from home but should not be muddy.
- If there are no shade trees on the property then I can tell you that the south facing side (receives full sun daily) will dry out the most and the north is shaded by the homes shadow
- During the summer months ( July through September) you may implement a sprinkler schedule that runs 4 times a week 20 minutes on the south, east and west side and 12 minutes on the north side, to balance moisture content evenly around the home. You should remember to take a walk around the perimeter once a week to review the moisture content in the soil and adjust stations to help keep moisture in the soil consistent around home
- Winter months will need very little watering however we do have dry spells even though it is cold out. You will still need to water in the winter but not as aggressively.
- Checking the soil – you know it is to dry when you see the soil pulling back from the foundation (small separation between lawn and foundation), cracks in the earth next to the foundation or when you pick up the soil and there is no cohesion of the soil when pressed between your fingers.
- During unusually hot summers be advised that the sprinklers provide only shallow water penetration and will not be enough to keep the foundation moist. A soaker hose and time clock can purchased at Home Depot.
Definitions:
soaker hose – a hose that you attach to your outside faucet which is designed to drip not spray
time clock – battery operated clocks which attach to the outside faucet can be programmed to automatically turn the soaker hoses on and off
T coupling for hose bib – this allows you to divide the faucet so you can still attach your garden hose leaving an extra connection point to attach the time clock with soaker hose.
With these irrigation tools you will be able to program a soaker hose which will provide deep watering penetration next to the foundation keeping the clay soil moist and pushing firmly against it. Soaker hoses should be placed 18 inches away from foundation when soil is level near the foundation and against the foundation when it is on a steep grade. You should only run these on a slow drip, if the water pressure is to high water will pool beneath the hose and will not be absorbed into the earth (either run off or evaporate) this is because the clay soil will expand when it gets wet and the moist upper layers will swell locking out further moisture penetration. Clay can only absorb a small amount of water per hour