The goal of drainage system installation around the perimeter of a foundation is to prevent water from soaking into the soil and moving under footings. Water can carry soil away from the footing with erosion, which causes the building to settle. If built over high clay content soils like we have in the Greenville, South Carolina area, poorly drained foundations are cracked or rotated by the expansion forces of the wet clay. Keep water away from foundations.More information about underpinning Sydney
When the grade around a house is well-sloped, it may be unnecessary to have a subsurface drainage system, but when atop soils that drain poorly like clay, the systems are vital to long-term structural integrity. Damp crawl spaces lead to fungus wood rot, thriving termites and the smell of mustiness, mold and mildew in the house. Doors and windows may stick. Stairs may even appear to rise and fall with floating slab syndromes.
There are two parts to a drainage system, the subsurface drain to carry away ground or subsurface water, and the surface drain to move rain or snowmelt away from home. A network of perforated pipes with the perforations pointing down in the bottom of trenches near foundations should be sloped so water seeping into the trench will rise into the drain and flow down to a receptacle. Above these pipes will be unperforated pipe to transport rain from roofs, patios and paved surfaces to a dumping site a minimum of ten feet downhill from the house. Combining the two will result in clogged pipes plus inject more water into the ground.
Three inch diameter pipes are usually sufficient but four inches may be needed in heavier flow areas, especially where there is a large roof area draining into a single downspout. Smooth-wall pipe rated at 2,000 pounds of crushing weight is fairly rigid and can be cleaned out with an electric snake. The earth is compacted above subsurface pipes so this is important. Under sidewalks or driveways, cast-iron pipe may be necessary. Clay-tile pipe or thin corrugated polyethylene pipe should not be used as it does not hold up. Corrugated galvanized-steel may be needed where there are large volumes of water, but a geotechnical engineer should be consulted.More information about underpinning
Cleanouts, similar to conventional waste-line plumbing systems, should be installed for electric snake cleanouts at 30 to 40 foot intervals on straight runs or near major bends, intersections, or where the downspouts enter the surface-water drain and leaves tend to clog. Use a plug that does not collect debris. Surface drains either need a area drain, catch basin, or trench drain of concrete or plastic with metal grills. Gravel covers the pipes to within one foot of grade and geotextile or filter fabric, made of woven or spun-bonded polyester or polypropylene fibers, folds over the gravel to keep fine sands from clogging the drain. Trench drains are long, narrow boxes with grills as the base of driveways to keep water from flooding garages downhill from streets.
It is a lot easier to install drain systems before foundation trenches are backfilled and homes landscaped. The cost is about three times as much on an established house. Old cast-iron pipes may rust out and clog with mud. What to do with the water is either to daylight the drain lines at the curb or with sealed hookups, sending the water to storm sewers if local jurisdictions allow it. Or leach fields, energy dissipation basins, or dry wells let runoff drain slowly but you may need a soils engineer to determine the soil stability. Dry wells in slopes can result in a landslide. Last resort is a sump pump to lift water out of an undrainable situation in the deepest part of the basement. This requires electricity which may go out when you need it most and it means that water is still getting into or under your house. Sometimes it is your only alternative.
In the Greenville, South Carolina are see the Andy Morris Construction website about channel drains. Brooks Landscapes handles french and foundation drains, and Fix My Foundation does repairs for foundation problems caused by drainage issues.
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When the grade around a house is well-sloped, it may be unnecessary to have a subsurface drainage system, but when atop soils that drain poorly like clay, the systems are vital to long-term structural integrity. Damp crawl spaces lead to fungus wood rot, thriving termites and the smell of mustiness, mold and mildew in the house. Doors and windows may stick. Stairs may even appear to rise and fall with floating slab syndromes.
There are two parts to a drainage system, the subsurface drain to carry away ground or subsurface water, and the surface drain to move rain or snowmelt away from home. A network of perforated pipes with the perforations pointing down in the bottom of trenches near foundations should be sloped so water seeping into the trench will rise into the drain and flow down to a receptacle. Above these pipes will be unperforated pipe to transport rain from roofs, patios and paved surfaces to a dumping site a minimum of ten feet downhill from the house. Combining the two will result in clogged pipes plus inject more water into the ground.
Three inch diameter pipes are usually sufficient but four inches may be needed in heavier flow areas, especially where there is a large roof area draining into a single downspout. Smooth-wall pipe rated at 2,000 pounds of crushing weight is fairly rigid and can be cleaned out with an electric snake. The earth is compacted above subsurface pipes so this is important. Under sidewalks or driveways, cast-iron pipe may be necessary. Clay-tile pipe or thin corrugated polyethylene pipe should not be used as it does not hold up. Corrugated galvanized-steel may be needed where there are large volumes of water, but a geotechnical engineer should be consulted.More information about underpinning
Cleanouts, similar to conventional waste-line plumbing systems, should be installed for electric snake cleanouts at 30 to 40 foot intervals on straight runs or near major bends, intersections, or where the downspouts enter the surface-water drain and leaves tend to clog. Use a plug that does not collect debris. Surface drains either need a area drain, catch basin, or trench drain of concrete or plastic with metal grills. Gravel covers the pipes to within one foot of grade and geotextile or filter fabric, made of woven or spun-bonded polyester or polypropylene fibers, folds over the gravel to keep fine sands from clogging the drain. Trench drains are long, narrow boxes with grills as the base of driveways to keep water from flooding garages downhill from streets.
It is a lot easier to install drain systems before foundation trenches are backfilled and homes landscaped. The cost is about three times as much on an established house. Old cast-iron pipes may rust out and clog with mud. What to do with the water is either to daylight the drain lines at the curb or with sealed hookups, sending the water to storm sewers if local jurisdictions allow it. Or leach fields, energy dissipation basins, or dry wells let runoff drain slowly but you may need a soils engineer to determine the soil stability. Dry wells in slopes can result in a landslide. Last resort is a sump pump to lift water out of an undrainable situation in the deepest part of the basement. This requires electricity which may go out when you need it most and it means that water is still getting into or under your house. Sometimes it is your only alternative.
In the Greenville, South Carolina are see the Andy Morris Construction website about channel drains. Brooks Landscapes handles french and foundation drains, and Fix My Foundation does repairs for foundation problems caused by drainage issues.
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