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Whatever surfacing you finally choose, there will be only one of two
basic methods used in laying the paving: mortaring it to a concrete
base (this is the most permanent and satisfactory way, and naturally
the most expensive), or laying it on a tamped base of sand, cinders, or
some other porous material, or sometimes on a combination of two of
them. Cinders or crushed rock may be used where the soil is exceptionally wet, or where it is so heavy with clay that drainage is poor
when heavy rains occur. To make a good flat base for the paving
material, a layer of sand on top of this coarse drainage layer will be
necessary. The sand should be tamped down well to level it off.
There is a third paving material which we shall consider later on-
concrete cast in place-but for the moment we are concerned with loose
units of paving materials to be laid for walks or terraces. Of all the infinite number of paving patterns possible in a great variety of materials
and sizes of units, all will be laid in one or another of the above methods.
. . . sand base method
Because it is the simplest and cheapest method, this will appeal most
strongly to the amateur. But considerable care and skill must be exercised to obtain really good results, even though it would seem that
basically all one must do is to grade the soil to the proper depth, lay a
bed of sand to the proper thickness, and then place on top of that the
paving material chosen. If any of these basic operations is not done well,
the result will be far from pleasing and will require much work of replacement and maintenance.
Let us first remember that sand will settle even after it has been
wet down and tamped. The weight of the paving material will pack the
sand somewhat, and the weight of use and traffic will pack it still further. This will make the level of the paving uneven, and it will be lower
than you had thought it would be in the beginning. Therefore allow 1/2 to
3/4 inch of space for settling and, when paving walks, crown the center a
little so that, where the general traffic will be, repeated use will
gradually pack down and level the walk. Should any particular units
sink out of line, it is comparatively easy to pry them up and fill under
them with a bit of sand and then replace them.
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