This book is what I've been looking for, college type material for the person who likes to self teach. Thank-you

This is an informative book that would be acceptable material for the person who has never been on a roof. He covers most roofing products in a adaquate manner explaining many of the basic princibles. However, as a roofer, it would have been nice to see what he considers acceptable manhours per square on each product, using his experiance, instead of using information drawn from other books.