If the house is located on ground ascending from the highway, with still higher ground in the rear of the house site, it is necessary to provide a plateau for the building (Fig. 65). This should be approached with a bold hand and the cutting out behind the building made broad and generous to avoid a sense of being shut in. The revised surface should be sloped away from the building in all directions. The minimum fall on the axis of the building should be one-eighth of an inch to the foot, while from the center toward the ends of the building at least one-quarter of an inch to the foot should be provided for.
Somewhat the same conditions prevail on ground descending from the highway (Fig. 66). In both instances the precaution of waterproofing the house foundations, either with a tar paint or by building them of waterproofed concrete, should not be overlooked.
The lawn surface around the house should have a minimum slope of one-half an inch to the foot and care should be taken to see that the sub-grade has a similar inclination (Fig. 67). No matter how great the surface slope away from the house is, if the old natural grade pitches toward the foundation walls the water percolates through the new fill and runs down the foundation walls to the cellar. Such a condition may also be overcome by filling in around the house with a stiff clay, if available, this to be thoroughly tamped or, still better, puddled. This sub-grade should have a slope of at least two inches to the foot for a distance of four feet from the foundation walls. Beyond that it may be reduced to one-half inch to the foot.
Occasionally the ground falls away enough to have a point lower than the cellar floor. In such instances it is a wise precaution against a damp cellar to introduce a three or four inch agricultural tile around the base, laid with open joints and half collars placed over each joint to prevent the soil from falling in and clogging the orifice. Where drive and walk drains exist this line of pipe may be connected with that system.
Generally speaking, the surface beyond the buildings may be left as found so far as the contour of the ground is concerned; the exception being small properties where it is possible to modify all lines of grade to suit the house without entailing too great an expense.
On larger properties it is only necessary to soften steep depressions or humps by lengthening the slopes, provided, of course, that the surface water may be drained off. Where depressions are large and the work entailed to carry the surface water off over the surface is too extensive, a catch basin should be provided. From this the drain may be projected to a lower point of grade or to a small well. Such a well should be about three feet in diameter and four feet deep (Fig. 68), this to be filled with stone to within twelve inches of the top, over which place the top soil. Draining to such a well is preferable to running it out on the surface. Drainage to a well spreads by seepage over a large area. In case a sewer line has been installed in the streets it is much better to connect with it, but extreme care should be taken to see that the line of pipe is properly trapped to prevent sewer gas from backing up in the pipe lines.
Fig. 70. - A section showing revised grade for lawn when the house is located lower than the pavement.