1. Field of the Invention
This invention relates generally to a method and diverter for directing water away from a building foundation, and more particularly, to a method and diverter which keeps the soil about the foundation dry, reduces the frost penetration depth in the soil about the foundation, can be installed about new or existing foundations and readily provides access to a portion of the foundation for inspection.
2. Description of the Related Art
Due to potential health concerns, high levels of humidity within a building or home are undesirable. For example, high levels of humidity significantly contribute to the growth of many microorganisms, such as dust mites, mold and mildew, all of which may produce allergens, toxins and irritants and produce unwanted odors.
Additionally, high humidity can cause serious damage to the structure and contents of a building. For example, wall and ceiling finishes can turn black from mold, which also can grow in clothes and bedding. Fungi can grow in building cavities, paint finishes can peel prematurely and window frames and sills can deteriorate.
Humidity within a building can originate from many sources including breathing, showering, cooking, cleaning, plants and clothes dryer discharge into the living space. The largest and most damaging source of moisture, however, is a wet foundation which typically is attributed to rainwater.
To provide desirable levels of moisture, a structure must be properly ventilated and the source of moisture, typically rainwater, must be reduced as much as possible. Once the soil close to the foundation becomes wet it is very difficult to keep the basement or crawl space defined by the foundation dry and, in turn, the remainder of the building or house.
Existing building practices stress the importance of controlling moisture but typically rely only on venting to relieve excess accumulations. Venting alone, however, does not provide enough moisture reduction. Additionally, newer buildings and homes are built to be "tighter" in order to reduce heating and cooling costs and drafts. These newer "tighter" buildings, however, reduce moisture within a building at a much slower rate.
Rainwater typically originates from the direct rainfall on and about a structure as well as from runoff from surrounding lots and structures which may be uphill from a particular structure. This rainwater can be diverted away from the structure to a surface or sub-surface or "sub-grade" drainage system. With a surface system, the type of soil utilized should be relatively impermeable and graded to a visible slope away from the structure which typically is at least one-half inch per foot. With a sub-surface system the rainwater typically is drained to a buried pipe which must remain unclogged and effective whether it drains to a sump pump, municipal storm system or ambient atmosphere.
Even under ideal diverting conditions, some water can accumulate in the soil surrounding a structure. Thus, in addition to venting and diverting, foundation walls typically are "damproofed" with a coating of bitumen and/or a layer of plastic placed beneath the concrete floor slab to retard movement of water vapor into the building. Furthermore, as a backup, a sump pump often is installed to collect and discharge any water that may accumulate in the soil or gravel beneath the floor slab. Such methods, however, are not effective when the soil surrounding the foundation is saturated.
Dry soil about a foundation also contributes to energy savings within the building. Dry soil about a foundation adds considerable R-value to the foundation since dry soil is a thermal resistor and wet soil is a thermal conductor.
Three structural problems also can be reduced or eliminated by maintaining dry soil about the foundation. The first is "frost heave" which is the swelling of wet soil when it freezes. Frost heave may occur beneath or against the foundation and actually can lift parts of the building. Although heat loss through a foundation sometimes can maintain the soil thereabout above freezing temperatures, it is preferable to keep the soil dry so as also to save energy costs through heat loss reduction.
The second structural problem is the swelling of the soil. This, especially, is a problem in regions having clay in soils since when clay becomes wet it exerts enormous pressure on foundations sufficient to cause distortion.
Finally, a widespread problem appears as horizontal cracking in foundation walls and occurs when soil surrounding a foundation goes from very dry to very wet. When dry, the soil shrinks and creates vertical crevices between the soil and the foundation. Debris then accumulates in the crevices and, after the next rainfall, the soil swells back to its original position with the addition of the debris. Over time, this causes the foundation wall to bulge and eventually crack, typically in a horizontal direction. In any event, dry soil or at least soil with a stable moisture content virtually eliminates all of these problems.
In attempting to provide dry soil about a building foundation, current building practice employs a combination of construction techniques based on building codes, traditional practices and new products. Building codes often require specific soil slope and footing drains, vapor retarders in walls and ventilation in attics and living and crawl spaces.
Traditional building practices vary from region to region. A standard practice for most areas typically includes footing drains surrounded by gravel and connected to a sump pump, a gravel base and plastic barrier beneath the floor slab, and damproofing of the foundation walls.
For foundation walls, it is increasingly common to provide a vertical drainage barrier having a filter attached to drainage board. The filter is a water permeable membrane or fabric which permits water to enter into the drainage board constructed of a material which provides vertical drainage to a subgrade pipe or tiles. Such barriers, however, require excavation to the bottom of the foundation, depend on the successful operation of the footing drains, easily can overload the footing drain and can become clogged.
One construction solution to water problems within a structure is a de-watering system. Such a system typically creates openings through the foundation walls permitting water to enter the structure and then directing water to a sump pump through an interior gutter system. Such systems not only permit the foundation to become wet, thereby incurring the various mold and structural problems discussed above but place an even greater dependence on the proper operation of the sump pump and its associated power system.
In order to divert water away from a building foundation and insulate the surrounding soil to reduce the frost penetration level, it also is known to provide rigid insulation about the exterior of a building foundation. An example of such a method is disclosed in BUILDING FOUNDATION DESIGN HANDBOOK, Kenneth Labs, et al., prepared by the Underground Space Center, University of Minnesota, 1988, pp. 65, 67 and 132-136. Those pages illustrate several slab-on-grade insulation placements as well as a horizontal "flowerbed" retrofit application having rigid insulation firmly adhered against a portion of the foundation and sloping away into the soil a predetermined distance. Although such rigid insulation can include a protection board, coating or flashing on one surface thereof, such a coating only is provided on a portion of the vertical section in contact with the foundation wall. Additionally, except for the adhesion between the insulation and the foundation, no specific connections are disclosed.
It therefore would be desirable to provide a method and diverter for keeping the soil about the foundation of a building dry which also reduces the frost penetration level within the soil, readily can be installed to new and existing structures, provides waterproof connections between adjacent diverters and between the diverter and the building wall which readily can be removed and reinstalled to allow inspection of the foundation.