I don't know how much you plan on spending but you might look at some Tarter Kennels. You buy the different panels and build them
10 x 10 or 5 x 10. These are heavy duty kennels. They are nothing like Tractor Supply or pet store type kennels. They are built by
Tarter Farm and Ranch Supply and sold at large farm co-ops and Ag stores. They come with a powder coat finish. Mine are 3 years old
and not a speck of rust anywhere. Mine are 10 x 10 and if I remember right they were about 550. per kennel. Check out the link.
http://www.tartergate.com/switch.php?fn=catalog.details&cod=DKFHDG&site=gsa&emp=gsa 
We put 4 x 4's across top and corrugated tin roofing on top of 4x4's. Our slab has 3 1/2 in. slope to it.
