The present invention involves building sheets with a plurality of grooves indented into a surface of the building sheet to provide a guide for cutting the building sheet along the grooves. Preferably, the grooves are arranged in a regularly repeating pattern and are spaced apart by a standard unit of measurement in order for a cutter to accurately size the building sheet to a precise dimension. A simple scoring knife is preferably used to score the sheet along the grooves, without the need for a straight edge, and the sheet is broken by simply bending the sheet of along the score mark. The grooves are preferably provided at a depth into the surface the sheet such that they do not substantially decrease the strength of the sheet or affect off-groove scoring. Thus, a score mark can be made between or across grooves without deflection of the mark into a groove and without breakage of the sheet along a groove when the sheet is bent.