I made this for my friend so she had something to put over here while she's watching tv. Cold winter months in the Mid West. It's made of Half Double Crochets. I don't make blankets as 1 whole piece I make columns, changing colors often, and sew them side by side. That prevents me from having to turn a very heavy blanket every row. Not good for the back.
Info on this pattern can be found at http://crochetpatterns09.blogspot.com/2012/12/plaid-blanketafghan-made-in-columns-no.html