Concrete forms

Claim 1

A RECTANGULAR METAL SHEET HAVING LONGITUDINAL CORRUGATIONS PARALLEL TO A PAIR OF OPPOSITE SIDE EDGES, THE OUTERMOST CORRUGATION ALONG EACH OF SAID PAIR OF SIDE EDGES DEFINING THE TERMINAL SIDE PORTION OF THE SHEET, EACH OUTERMOST CORRUGATION HAVING AN UPWARDLY AND OUTWARDLY INCLINED OUTER SIDE WALL TERMINATING AS ONE OF SAID SIDE EDGES, A BOTTOM WALL EXTENDING TRANSVERSELY OF SAID SIDE EDGE AS A CONTINUATION OF THE LOWER PORTION OF THE OUTER SIDE WALL TO DEFINE THE BASE OF SAID RESPECTIVE OUTERMOST CORRUGATION AND AN UPWARDLY AND INWARDLY INCLINED INNER SIDE WALL EXTENDING AS A CONTINUATION OF SAID RESPECTIVE BOTTOM WALL AND TO A POSITION AT LEAST ABOVE A PLANE CONTAINING SAID SIDE EDGES, THE TERMINAL PORTION OF EACH OUTER SIDE WALL DEFINING SAID SIDE EDGE BEING DEFORMED ALTERNATELY ALONG THE EXTENT OF SAID SIDE EDGE AND TRANSVERSELY INWARDLY AND OUTWARDLY BEYOND PROJECTED CONTINUATIONS OF THE FACES DEFINING THE PORTION OF THE RESPECTIVE OUTER SIDE WALL IMMEDIATELY BELOW SAID DEFORMED TERMINAL PORTION FOR PROVIDING CONTIGUOUS TRANSVERSE VENTING AND SPACING CORRUGATIONS, THE TRANSVERSE CROSS SECTION OF EACH OF THE OUTERMOST CORRUGATIONS AT THAT PORTION OF SAID INNER SIDE WALL IN THE VICINITY OF SAID PLANE BEING SUBSTANTIALLY CONSTANT ALONG A STRAIGHT PATH FOR SUBSTANTIALLY THE LENGTH OF THE RESPECTIVE OUTERMOST CORRUGATION AND DEFINING A SURFACE OF SAID INNER SIDE WALL FREE OF TRANSVERSE CORRUGATIONS, AND THE DISTANCE BETWEEN THE OUTERMOST SURFACES OF EACH OF SAID OUTERMOST CORRUGATIONS INTERSECTED BY SAID PLANE BEING AT LEAST AS LARGE AS THE DISTANCE BETWEEN THE INNERMOST SURFACES OF THE OTHER OF SAID OUTERMOST CORRUGATIONS INTERSECTED BY SAID PLANE FOR PROVIDING VENTING SPACE BETWEEN THE OUTER, INNER AND BOTTOM WALLS WHEN THE OUTERMOST CORRUGATIONS OF ADJACENT SHEETS ARE NESTED.