This room was initially used as a workshop for a wood crafting hobbyist (when home was purchased in 1950). The plan to eventually turn it into a spare bedroom/guest room was never realized. Instead, it became a room to store belongings (since 1970). Imagine an “attic room”, for the past 38 years.
The room was originally painted in a dark green/cream colored paint, appears to be a matte finish. It has never been repainted. The floor has me puzzled. Has a somewhat rugged look, wooden planks (not very wide) which appear to be painted or stained with a redwood look. I keep thinking of picnic table wood. Keep in mind, this room was originally dedicated to home projects, so lots of saw dust collected on the floors, back then, too.
My intention is to use this room as a productive living space, possibly an art studio. I know primer will be necessary. Which would be the best type to use, considering the walls are so dark? How can I best prepare the walls, prior to using primer paint? Will I be able to select any light colored paint of my choice, following the primer coat(s)? Any suggestions on how to proceed with treating the floor? Indoor paint for floors(????) or perhaps having carpet installed over existing floor.
You already know where to start, a very good cleaning. The walls, ceiling and trim should be washed with a TSP, trisodium phosphate, cleaner and rinsed well. If TSP isn't available, use ammonia and water.
Now these surfaces need a light sanding to roughen them up a bit for the best bond. I would use a pole sander and 120 grit sandpaper for the walls and ceiling. The trim can he hand sanded with medium grit sanding sponges. Give all sanded surfaces a quick rinse to remove any dust.
Priming, as you know, is critical. I would use Zinsser Cover Stain as the primer. It is an oil based primer, it will smell bad for a while. Open all windows and use fans for good ventilation. The good part is it will dry fast and the smell will dissipate in a few hours. Allow the primer to dry overnight before painting.
The primer is white so it will cover the old color a bit. The good part is you can use any paint color you want and you don't have to use oil based products from this point on. Plan on two coats of paint for the best coverage.
Don't give up on the floor just yet. It could be refinished by a flooring contractor. It is possible the wood is really nice and just need a good sanding and a couple coats of a urethane to bring it back to life.
The best way to check it is sanding a 2×2 area to reveal the wood and take a look. Do it yourself if you have a belt sander or ask the flooring contractor. If you think it isn't worth it then carpet over the wood.