Ha! I was always advised to add a month and 5K to any quote for a decent size renovation job to cover, you know "Hey, it just came up, mista'...." type stuff... :)
I haven't gotten any quotes, except on materials, because we are doing all the work ourselves - thus the increase in her piggy bank :)
I suspect I'll being posting pictures of me swinging a hammer reshingling the roof in the very near future........