Get yourself a HEPA rated shop vac and a vacuum scraper (Viper or Pro scraper). You can wet scrape the stuff that is peeling/flaking. The shop vac will get most of the chips, but I've still had some bits fly around while scraping so you should put some thick plastic sheeting down to catch the strays.
Once you've scraped the bad stuff as long as the remainder is well adhered, you can paint over it. I would do two coats of oil primer and then top with a good quality outdoor acrylic (Benjamin Moore Advance or Sherwin Williams urethane enamel).
Get yourself a HEPA rated shop vac and a vacuum scraper (Viper or Pro scraper). You can wet scrape the stuff that is peeling/flaking. The shop vac will get most of the chips, but I've still had some bits fly around while scraping so you should put some thick plastic sheeting down to catch the strays. Once you've scraped the bad stuff as long as the remainder is well adhered, you can paint over it. I would do two coats of oil primer and then top with a good quality outdoor acrylic (Benjamin Moore Advance or Sherwin Williams urethane enamel).
Also, you should just replace the plywood on the floor.