We are currently doing up a rental property in return for cheap rent with option to buy. The interior paint is cracked and peeling in many places. The paint that peels off is 1.5 mm thick. What is the best way of preparing the walls for painting? How much should we scrape off? I'm worried that if we don't scrape enough off then the paint will only peel or crack again... but to scrape all off is a massive job... Really have no idea what to do so any help would be much appreciated. Thank you.