Abstract: A clapboard installation layout guide and method uses an elongate tape having two sets of indicia including a first plurality of "to the weather" indicia spaced apart at intervals approximately equal to the "to the weather" width of the clapboard and a second plurality of indicia including curved tracks with centers at corresponding ones of the first indicia and having a radius approximately equal to the full width of the clapboards; one of the first indicia on the tape is aligned with one boundary of an area to be laid out for installation; with one of the first indicia of the tape aligned with one of the boundaries, the tape is swung so that the first indicia just beyond the other boundary of the area is coincident with the other boundary; clapboards can then be applied to the area so that the upper edge of each of the clapboards is tangent to the successively higher ones of the second indicia until the area is covered including the installation of the starter clapboard of the next area to be covered.