i would'nt bother you will be changing them in a couple of years the sun deteriorate them you would be better off with corrigated bitchermin type.
Having a laugh arnt you mate .That stuff aint worth a wank .Goes brittle in the sun and bows and leaks in the winter .The sheets i used were off a job i did ,not second hand just surplus and cost about a tenner each for 15 foot lengths .
f**k no's what shit you used ive had my b/roof on my kennel for the last 10 years if supported well dont sag mine is in the sun most of the day never gon brittle. plastic crap deteriorates in the sun uv rays .