A drainage structure having perforated parallel top and bottom plates separated by spacer members. A web joins adjacent spacer members and has a curved profile such that water spilling over the web does so, at a varying velocity profile to increase oxygenation of the water. This drainage structure can also be filled with good drainage soil and planted with grass to filter and retain water that passes therethrough, with a layer of filter medium below and a water permeable drain below the filter medium, to transport water into the substrate and into a reticulation tank where the water can percolate back into the soil.

Improvement in a system for protecting foundation walls and the like, said system comprising at least one main protecting sheet made of relatively thin, stiff material and including protrusions formed therein, for thereby providing air channels and channels for receiving water from back fill. In order to provide a complete coverage of such foundation walls even by varying height thereof, and in a far more efficient manner, the improvement comprises pre-cut top sheet elements and bottom sheet elements adapted to be mounted along a foundation wall prior to the mounting of said main protecting sheet thereupon, so as to achieve full protecting coverage of said foundation wall in a more rapid and time-saving manner on site. The system also allows for pre-cut corner sheet elements adapted to cover the merging portions of an inner corner or an outer corner of a foundation wall and also adpated to be mounted prior to the mounting of the main protecting sheet thereupon. Special elements are suggested for covering the area of outer or inner corners merging with foundation wall footings.

A separation layer (12) for laying grass surfaces (10; 16) on a sand or gravel base (13), which layer is in the form of a rigid plastic sheeting with parallel side edges. The surface of the sheeting is embossed by thermo-forming so that it presents a uniform pattern of deep embossings (14). These form rows which extend perpendicular to said side edges. The parallel rows are each connected to adjacent embossings in the same row via bridges (15) so that each row of embossings in cooperation with adjacent rows creates a stiffening of the sheeting.

An earth drain comprising a core consisting of an elongated flexible web having on at least one surface thereof, and preferably on both surfaces, an array of discreet projections spaced transversely across the width of the web, and longitudinally in the lengthwise orientation of the web. The array of projections is interrupted by a plurality of elongated projection-free zones extending in the longitudinal direction of the web, and spaced transversely across the width of the web. A filter of sheet-like water permeable material encases the core, and is adapted to be maintained in spaced relationship to the web by the free ends of the projections thereon.

A spandrel supporting an upper story upon a lower story of a construction having exterior and interior walls bounding a site for collecting water seepage through the porosity of the brick construction material of the exterior wall, on which spandrel there is a waterproofing membrane to confine the water seepage to the space between the walls and a porous drainage fabric to drain excessive water to the exterior and as to nominal seepage to allow air flow through the drainage fabric to cause its evaporation.