ATTENTION: BORING BLOG POST AHEAD. Proceed only if you require more details about applying wallpaper primer to OSB than the words "applying wallpaper primer to OSB" communicate.My plan is to cover my walls in wallpaper liner. Wallpaper liner--AKA wall liner, and several other names--is a thick, plain kind of wallpaper that is used to create a smooth, paintable surface where once there was cinderblock, horrid wood paneling from the 70s, decrepit wallpaper, or some other undesirable surface that would be a pain in the neck to remove (like... an OSB SIP skin). It's a pretty simple DIY task with only one real prep step: priming the surface with wallpaper primer.
