John Flynn explains a neat method for diagonally piecing a wider quilt back from 44" wide fabric. I highly recommend it.
click here and scroll halfway to "diagonal pieced back".
http://flynnquilt.danemcoweb.com/workshop/FreeLessons/
And, coolness! He has an app that will do the math for you! According to his math, you will need 52" of 42" wide fabric to back your quilt IF you piece it diagonally.
I love apps.
