foot panels. They were smooth on the outside, but waffle-ribbed on the inside, using 50 percent less concrete than the normal wall, and placed on 6-inch thick pads, 3 foot square, at each end of the panels (Grady, 1993). Superior Walls is another US precast system that uses only a third of the typical concrete wall (Wilson, 1993); it is also built with rigid insulation formed right into the panels. Superior has 23 franchises in 18 states (Superior Walls of America Ltd., 2003). Another increasingly popular way of conserving concrete is the use of block and form products that not only use less concrete but in most cases actually increase the insulating value of foundations. This is important since regular concrete is a poor insulator. Among these materials, the oldest is Durisol, first manufactured in Europe in the forties and here in Ontario beginning in the fifties. It is basically a fibre-cement producta concrete made with Portland cement but with mineralized wood shavings as the aggregate, instead of sand and stone. The mixture is used to make stay-in-place wall forms for concrete structures, and strong but lightweight blocks for sound barriers, retaining walls, and other uses. The blocks are laid up without mortar, rebar is inserted in the hollow cores and concrete is poured in. There are mineral wool insulating inserts for the form panels. The Durisol wall is strong, insulating; rot-, fire- and pest-resistant; noncombustible; uses waste wood materials; and is environmentally benign. It is quite popular for high-rise construction for its economy as well as its sound-proofing qualities (Durisol Industries, 2003). It has spurred a number of imitators with varying ingredients and characteristics. Other kinds of insulating foundation systems (IFS) exist that can reduce concrete use but are designed primarily to insulate. As with Durisol, they are mixtures of cement, with either wood waste or foam (usually expanded polystyrene,