Chapter 5

Construction Problems

Not every house is blessed by ideal surroundings, with promise of easy creation of outdoor recreation and entertainment areas, a good lawn and a good garden. Often it is necessary to undertake a certain amount of construction to insure the quality and life of tree gardens you wish to plant and the terraces you wish to build.

The basic construction problem of any landscaping is the grading of the soil. In essence, grading means building a slope or slopes into your property. Such slopes assure the proper drainage of water, beautify the aspect of the house and make for easier maintenance. Whether you intend a lawn, a garden or a terrace, grading comes first.

The best time to consider grad­ing is when you undertake construc­tion of your house. It is a simple matter to ask for a few additional inches between the entrance level and the ground level. Yet these few inches will insure the easy develop­ment of a grade away from the house wall to improve the appear­ance of your surroundings and ob­tain a drier basement.

Rough Grading and Drainage

Rough grading is the first step in lawn, garden or terrace construc­tion. The extent of the grading will depend upon the condition of the ground, the desired ground levels and the attention that must be given to extreme slopes. It is important to adhere as closely as possible to natural contours in grading, since this cuts expense considerably.

The first step in grading is to strip and separate topsoil from the areas in which the level is to be changed. Even if the grading is for construction of a stone or concrete terrace, saving the topsoil is im­portant. In this case, spreading the topsoil in areas which are thin, or using it in the flower garden, can save you a good deal of money.

Once the topsoil is stripped, the subsoil can be graded to the con­tours desired, leaving sufficient space for adding the topsoil you have already removed. Remember to plan on a slope. For a lawn, a gentle slope is best, most experts recommending a minimum of 6 inches in slope for every 100 feet in lawn.This same measurement can be effectively applied to stone ter­races as well, to prevent the devel­opment of pools of water in rainy weather.

Subsoil Drainage for Lawns and Gardens

Where the subsoil is thick or clayey, it is essential for the well-being of the lawn that subsoil drainage be installed. Even in sandy soil, it is a good idea to use subsoil drainage, since it brings about the quick and even distribution of moisture throughout the lawn or garden area. The first problem in drainage is to find an area to re­ceive the flow. If you are on low ground, on to which water from higher areas flows, this run-off area is extremely important. On high ground, an underground pipe lead­ing out over a slope will be enough.

If you are building your own drainage run-off, perhaps the easi­est is the dry well. The dry well is nothing more than a pit, 4 to 6 feet in depth and diameter, and filled with rubble and rock. Your dry well should be marked after it is cov­ered, so that you know where it is if water starts to back up on your lawn.

Subsoil drainage is best accom­plished by the use of tile lines. The semi-circular lines of tile are laid in the topsoil, about 1-| to 2 feet deep, in lines from 2 to 4 feet apart. The tile lines should be covered with about A foot of cinder or crushed stone before the soil is re-laced. The minimum effective grade for tile lines is 3 inches for every 100 feet in length.

When backfilling, be sure to put all the subsoil you have removed back in and tamp it down, if neces­sary. Any slight mound left after re­storing topsoil will disappear after the first winter.

Measuring Your Grading

It is very difficult, even for a professional, to measure grades by eye. It is doubly difficult for the amateur. Therefore, if you have a grade to level, use as a guide a piece of twine that is pulled tight between two sticks imbedded in the ground. For leveling, once you have done the rough work, use a long board as a straight edge along the ground to insure your accuracy.

Grading for Terraces

In leveling an area for a terrace, there is no need to insert subsoil drainage. Save the topsoil. For al­most all terraces, it is a good idea to tamp the soil, and even to pour a quantity of gravel cinder or crushed rock as a base. Terraces re­quire a level area as a rule, but the grade sloping away from the house should be maintained.

Terraces

Terraces present wonderful pos­sibilities in the garden. They are outdoor living rooms during good weather and form a transition from the outdoors to the indoors through­out the year.

The terrace may be either at ground level, below ground level, or raised above it. The simplest type is ground level, which requires only the grading we have indicated. There is a wide choice of flooring materials to use. One may use ce­ment, poured and leveled with a large board, but in maintaining the drainage grade or including shal­low drainage paths, smooth turf may be used, in which case the preparation will be the same as for other lawn areas and various other types of bases.

The use of flagstones is made simple by applying a load of sand or gravel to the subsoil and digging the flagstones into the sand or grav­el. The niches between the stones can be dug out and filled with top-soil and grass or other cover planted between them. This gives a very pleasing effect.

Hollow clay building tiles can be split and laid as units in the ter­race floor, their rough edges in the soil. Another good surfacing ma­terial is "exposed aggregate," which is free from glare because of its rough finish. For this type of sur­face, build a form of 2 x 4's.

For areas of dry and scarce sun, use neat gravel adging and evergreen cover

Pour the flooring in squares, one square at a time, and level with a straight board. The material used is a mix­ture of cement, sharp sand and crushed rock or pebbles.

Redwood or cypress blocks may also be used for terrace floors and are very attractive, although some­what less durable than stone or brick. You can buy the blocks cut to size and lay them directly in a bed of sand, which in turn has been laid on compacted gravel or cinder. Unmortared brick, laid in a pat­tern, on 2 to 4 inches of well-tamped sand, with loose sand in the crev­ices for grass, makes a hardy and simple-to-construct terrace floor. The bricks may be laid flat or on end, and to keep them from spread­ing, drive an angle iron against the corners. Use a pattern that follows the lines of your terrace.

The Sunken Terrace

A sunken terrace is one which is below ground level. It can be very attractive, and it does give a feeling of coolness on a humid day or a hot night. The sunken terrace requires a retaining wall to prevent soil from continually eroding into it, and also to maintain the topsoil of the sur­rounding garden. The subsoil must be dug to a depth of about 5 or 6 inches below the level you wish to attain with the terrace itself. The use of sand or gravel as a base is of importance. The top treatment can follow your own dictates.

The Raised Terrace

The raised terrace is generally not fully raised, but starts at the house level and is raised at its outer edge. Again, a retaining wall is called for. The principle problem with the raised terrace is leveling. Once this is accomplished, and the retaining wall built, construction follows the same procedure as in any other case. Drainage is sup­plied either by a central drain, going into a tile line, or by under­ground piping through the retain­ing wall.

Retaining Walls

Beautifying your garden by the construction of a retaining wall, be­hind which is a lawn or expanse of flowers, is not a difficult task. But, like all garden problems, it requires a certain amount of effort and care. The retaining wall must be strong enough to hold back the pressure of a great weight of soil, and yet por­ous enough to allow drainage.

The most popular types of walls are built of stone, either dressed or rubble. In using stone for a retain­ing wall, there are two basic types of construction: dry-wall, which uses earth as a filler between the stones, and mortar, which uses ce­ment as a bonding agent.

The base of any retaining wall must be sunk below the frost line. This is about 6 inches in the north­ern half of the United States. As a rule of thumb, for a flat wall (one without buttresses or projections), the width of the base should equal one-fourth the height of the wall. The wall can taper to a width of about one-fourth of the width of the base.

For buttressed walls, the base should be one-fourth as wide as the wall is to be high. This refers to the widest points, where buttressing is to be used. In the narrower areas, the base may be of slimmer propor­tions.

At intervals of about 24 inches, and about 6 inches from the lower ground level of the retaining wall, drainage pipes should be imbedded in the wall. In some walls, if the wall itself is porous enough, it is possible to eliminate these drains. But in any construction using mor­tar as a bonding agent, these drain age pipes are essential.

In dry-wall construction it is possible (although not advisable) to start at ground level, and not sink the wall below the frost line. The most inexpensive way of construct­ing a dry wall is to choose local stone, picking large ones for the main stones and smaller ones for the chinks. The largest stones should form the base of the wall with the smaller ones leading to the top. The side of the wall which faces out should be as level as possible, with obstructions and edges of outside stones facing inward. This not only gives the wall a better purchase on the soil it retains, but also insures a good appearance. Stones with round surfaces should be discarded since they do not form a good wall.

Stones should be placed in a good bond. This simply means that edges of stones on one course should overlap spaces in the lower courses. Where a stone on an upper course is crooked or does not fit firmly, earth and small stones can be packed in to improve the bond. No vertical crevices should be left.

The wall itself should slope back against the soil it is retaining. This gives it greater strength. The width of the base of the wall should be, again — as a rule of thumb — one-third of the height. It is the practice in many areas to slope the wall as much as 5 or 6 inches for each vertical foot, although this de­gree of slope is not essential. Soil should be firmly packed in all pock­ets in the wall and should be con­tinued back into the earth being re­tained.

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