i've been fitting pvc roofs since 1984 covered my kitchen extension in 1986 (sarnafil)and still in excellent condition in that time i have laid trocal flagon sucoflex protan
sarnafil pvc has been in production since the early 70's your problem is down to poor workmanship it was discovered in 1990 that if sarnafil is left in the rain for long periods it can not be welded this could be the problem if your material was old
if it was welded in wet/cold conditions (or lister gun not set at the correct temperature appox 320 degree) it can be rewelded if not it will need to be cleaned and over laid with a wider cover strap
sarnafil pvc has been in production since the early 70's your problem is down to poor workmanship it was discovered in 1990 that if sarnafil is left in the rain for long periods it can not be welded this could be the problem if your material was old
if it was welded in wet/cold conditions (or lister gun not set at the correct temperature appox 320 degree) it can be rewelded if not it will need to be cleaned and over laid with a wider cover strap