I had a roofer (independant contractor) inspect our roof and there is some rot so leaking is only a matter of time, like the next rainfall since he poked his finger through some of them to illustrate. He said he can replace the rotting shingles (about a dozen) and treat the remainder to halt any further curling and or drying out and rotting for about 1800 dollars (canadian). He can do this all by himself in 3 days. I know zilch about this sort of stuff. This seems like a lot of money for three days work for one person. What kind of materials would he be using that would cost that much? The roof is about 1000 sq feet. Now I understand how little old ladies can be taken by unscrupulous door to door maintenance men.