dotty- I made the following log cabins using a poly foundation fabric (aka well used dryer sheet)and 3/4" ( for the 1/4")and 5/8" (for the 1/8") wide fabrics with 1/4 seams. Pieces were cut before sewing. Some PP patterns are also that small.
http://www.quiltingboard.com/t-43789-1.htm