Can you put primer over paint and then paint or must you always scrape away the old paint first??

I know it'll be bumpy if I don't sand the old away, but it's for a lil crappy project ouside so I just wanted to know if it would work.Can you put primer over paint and then paint or must you always scrape away the old paint first??
If you don't want to have to do this again next year, then I strongly suggest first using a scraper to get rid of all the old paint that has loosened enough to peel. Then take some sandpaper and sand down the edges of the remaining paint so that there isn't an obvious ';ridge'; between the wood and the paint.





THEN you can prime.Can you put primer over paint and then paint or must you always scrape away the old paint first??
The undercoat must be tight, that is not flaking, peeling, etc. Putting primer over the top is fine.
Make sure your surface is clean then put primer on. Then you are ready to paint.
Most primers are designed to adhere to existing paints, providing a nice foundation for your new paint to adhere to. If you want to paint over a high gloss paint, a primer will do the job. Do not attempt to skip the primer. Having said that, you do want to use a screen to sand off bumps on the wall before you prime.
Any peeling paint should be scraped down so there is a smooth work surface. Then apply an even coat of primer and then paint. You should be good to go.
If you don't mind the project being ';bumpy'; then by all means prime it and paint it. Do make sure the surface is clean...no dirt or other stuff . I would use Kilz 2 which is a latex (easy clean up) and good indoors or out. It is also a stain sealer which helps avoid bleed thru.