I am a 68 yr old female and have been replacing termite chewed siding and now am painting, after scraping, wire brushing & sanding then power washing then had to scrape and wire brush AGAIN. After all this I am finally painting, since the remaining wood is all 40 yr. old (2013) and been previously painted only 2x's, last about 20 yrs ago. I decided to go with 3 coats of Behr w/primer. I know 2 coats would have maybe been fine, BUT it was really worn and since I couldn't afford new 2x12's I thought this was the best route. This being said, I DO NOT want to ever in my lifetime so this again, hopefully 3 coats will ensure that. I would like to know when you scrape do you just scrape the loose paint or do you have to take a sharpened putty knife and actually force the knife in to see if you can loosen the paint? I looked over the "Net" and found nothing about how to prep a house before painting. The one site said scrape to prep, and in the next scene he was painting. Not very informative. Thank You