on appearances, this is an important when you keep up with because paint does more than just make your house look good. If your home has any exterior components that are made of wood, paint maybe the only protection they get from the elements. But you can't just slap on new paint over old bad paint because it simply won't last and really won't look that good. If the coating that's there is cracked, peeling, or alligatoring, it has to be removed before new paint can be applied. Pressure washing first will remove the dirt and mildew plus some of the more badly deteriorated paint . But after that approach, usually, we'll use a rotary sander to speed up this job. And if you have very much to do, you may want to rent or even buy one to save a few blisters; otherwise, you'll have to rely completely on the hand tools they use for closed quarters, the scraper and the putty knife. Neither is any fine. The object isn't to remove all of the paint , just the stuff it isn't sticking well anymore. And when you do get down to bare wood, you wanna feather it out into the surrounding paint , so the surface is nice and smooth. Before you apply the new paint , you want to prime those areas where you've exposed the bare wood. The primer will give a top coat, something to bide into so that it'll stick better. After you caulk the gaps and cracks between boards, you're finally ready for the finish paint . But don't stop after 1 coat. Good prep work and 2 full coats of paint will mean you don't to do this again very soon. And you don't want to, do you?