Lay out your blocks as desired with four across and five down.
Now we are going to add the sashing. Take your 24 strips 2 1/2" wide and start sewing them on to the individual blocks on the right of the first three blocks in each row and one will be left with no sashing. Sew the row together. The way I did this (which you can do it any way you please of course) was to sew all the sashing together and cut as I went. I didn't care if I had a seam in one of the smaller sashing pieces.**
** If you do not do it the above way you will need additional yardage for the sashing.
Now once you have all of your rows together you will add the sashing horizontally between each row, starting with the bottom of the first row. Do not add sashing to the fifth row. Sew all rows together.
Then add your sashing to the left and right of the quilt top. Followed by the top and bottom of the quilt top. Again, I sewed all of my sashing together and just cut as needed.
Voila!! You should have something that resembles this. (my top row is over the back of the fence).
For the Backing Fabric:
Make three equal rows of fabric from your 7 1/2 yards and sew them together. You will have scraps to play with on another project...Yippee!!
Now layer, quilt, and bind as desired!! You are done!!