Tempo:
foundations subjected to hydrostatic pressure are also equipped with a means of relieving the water pressure to prevent structural damage.
backfill from clogging the drain. Backfill must not contain pyritic shale or materials finer than 4 mm (5⁄32 in.).
FOUNDATION DRAINAGE
Connect the drain pipe with a tight joint to a storm sewer or other satisfactory outlet. A sump may be necessary in some cases.
Foundation drainage is required unless it can be shown that natural, free-draining soil makes it unnecessary. Foundation drainage normally consists of a drain pipe installed around the perimeter of the basement and usually a wall drainage layer. A layer of granular material can be used in lieu of a perimeter drain for foundations such as preserved wood foundations, where the granular layer slopes to a sump. Adequate drainage is essential to prevent the infiltration of water into the basement. Drain pipe should be laid on solid undisturbed soil around the footings, with the top of the pipe below the level of the basement floor or crawl space, and with a slight slope to the outlet. Cover the pipe with a minimum of 150 mm (6 in.) of coarse, clean gravel or crushed rock (Figure 50). The pipe should be wrapped with a filter fabric “sock” to prevent fine particles in the
On wet sites, special drainage features such as lateral drain pipes under the floor slab may be needed to avoid hydrostatic pressures on basement walls and slab. Note that foundation drainage is not intended to deal with high water tables. Foundations located on sites with high water tables must be designed by an engineer. For a preserved wood foundation, a granular layer must be employed in combination with a sump. The granular layer must be at least 125 mm (5 in.) thick under the footings and extend at least 300 mm (12 in.) beyond the edge of the footings (Figure 47). Slope the bottom of the excavation so that it drains to the sump, which must be drained by gravity to a sewer, ditch or dry well, or evacuated by pumping.
50 Drain pipe at foundation wall
damp-proofing
150 mm (6 in.) coarse gravel or crushed stone on top and side footing perforated plastic drain tile
backfill from clogging the drain. Backfill must not contain pyritic shale or materials finer than 4 mm (5⁄32 in.).
FOUNDATION DRAINAGE
Connect the drain pipe with a tight joint to a storm sewer or other satisfactory outlet. A sump may be necessary in some cases.
Foundation drainage is required unless it can be shown that natural, free-draining soil makes it unnecessary. Foundation drainage normally consists of a drain pipe installed around the perimeter of the basement and usually a wall drainage layer. A layer of granular material can be used in lieu of a perimeter drain for foundations such as preserved wood foundations, where the granular layer slopes to a sump. Adequate drainage is essential to prevent the infiltration of water into the basement. Drain pipe should be laid on solid undisturbed soil around the footings, with the top of the pipe below the level of the basement floor or crawl space, and with a slight slope to the outlet. Cover the pipe with a minimum of 150 mm (6 in.) of coarse, clean gravel or crushed rock (Figure 50). The pipe should be wrapped with a filter fabric “sock” to prevent fine particles in the
On wet sites, special drainage features such as lateral drain pipes under the floor slab may be needed to avoid hydrostatic pressures on basement walls and slab. Note that foundation drainage is not intended to deal with high water tables. Foundations located on sites with high water tables must be designed by an engineer. For a preserved wood foundation, a granular layer must be employed in combination with a sump. The granular layer must be at least 125 mm (5 in.) thick under the footings and extend at least 300 mm (12 in.) beyond the edge of the footings (Figure 47). Slope the bottom of the excavation so that it drains to the sump, which must be drained by gravity to a sewer, ditch or dry well, or evacuated by pumping.
50 Drain pipe at foundation wall
damp-proofing
150 mm (6 in.) coarse gravel or crushed stone on top and side footing perforated plastic drain tile
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