Since the basic invention of U.S. Pat. No. 4,019,279, various types of root deflecting panels, etc., have been manufactured and sold for the purpose of deflecting tree roots downwardly so that they will not lift or crack sidewalks, curbs, etc. (called "static structures" or "hardscapes"). These panels are of the type in which spaced parallel ridges or ribs are molded integrally with or (adhesively secured to) body portions. Such body portions, having the ridges thereon, are secured endwise to corresponding body portions of adjacent panels by tongue-in-groove connector portions or elements. Any desired length of the connected panels may be employed, for example along a sidewalk or curb, or around a tree of any size.
Let it be assumed, for example, that the roots of one or more trees growing in a yard have lifted or cracked sections of a sidewalk. The lifted or broken sections of the sidewalk are removed, as are the offending roots, and a narrow trench is dug adjacent the edge of replacement sidewalk sections. This is preferably done by a special tool that not only trenches but also root prunes (cuts) the roots. Thereafter, connected sections of panel are dropped into the trench. There are, however, problems both at the time of inserting the connected panels and for years thereafter while the panels are doing their job of deflecting roots downwardly.
It is important that the upper edges of the connected inserted panels be sufficiently high that roots may not grow thereover. For example, if such an upper edge were slightly below the surface of the earth (grade), a tiny root could grow thereover and then (for example concealed by grass adjacent the sidewalk edge) grow beneath a sidewalk. Thereafter, such root could grow progressively larger and larger until sidewalk lifting or cracking could result.
Relative to the long time period after the connected panel elements have been embedded in the earth, if the upper edge is substantially above grade there can follow various undesirable results. One is that the upper edge is exposed to ultraviolet light from the sun, which can eventually degrade the synthetic resin edge so that it cracks off when stepped on (for example). In addition, the edge is relatively thin and can be damaged by the high-velocity rotating lines of "trimmers" (such as "WEED EATER" tools). Another problem is that the exposed upper edge has no appearance of solidity or effectiveness, which can cause users to believe that the root barrier is not being effective whereas in fact it is. Another problem is that an exposed thin edge of a panel may cut the feet of children at play.
A further problem relates to possible fraud by persons installing the root deflector panels in the earth between the trees and the static structures (hardscapes). If a root deflector panel is cut in half longitudinally, thus providing two elongate root-deflector half-strips each having a vertical dimension (when installed) approximately half that of the original strip, fraud can occur with very little likelihood of detection. Thus, the uncut edge of each of the two strips is caused to be slightly above the ground, and the rest of the half-strip is buried in the earth. Unless the supervisor or owner digs down and tests at various points to see whether or not a full-depth strip has been used, it is probable that the fraud will not be detected until many years later.