I have seen it done before and wanted to try it for years but hadn't gotten up the nerve I guess. Finally I had had enough of the rug with holes in it and decided it was now or never.
I pulled up the rug and discovered particle board underneath. Not surprising as this addition hadn't been finished when I bought the place. No problem, I was going to try the painting idea.
I didn't really need to sand it, but there were some nails that needed to be pounded down. I vacuumed it thoroughly and taped off the sides.
Surprisingly easy, I just rolled on a base coat of primer. I was prepared to apply a second coat but it didn't seem to need it or even a top coat of color.
I replaced the furniture and smaller area rugs and was quite happy with my results!!
I have since installed carpet tack strips along the existing carpet you see here.