drywall mud over painted wall

[Unregistered]

I have some sheetrock in my attic which I want to change to bedrooms which was mudded and painted by previous owner, problem is this has to be the worst mud job I have ever seen and no tape was used over the joints, I want to sand off some of the higher areas, add tape to joints and redo the walls. I was planning on getting some primer to go over the previously painted walls before I mud the joints, any suggestions on a type of primer that would be good for this, or is it not necessary to prime at all?

[dremmel]

I did this to my home in certain areas about four years ago. I didn't use any primer at all and have had no problems with it. Spackling compound or mud should adhere to painted surfaces as well as previously mudded areas without the need to prime. At least that's been my experience.

[mdshunk]

It is not necessary to prime areas that will be overlapped by joint compound. It will stick just fine. The biggest obstacle is sanding areas that have been painted over. It takes a good bit of elbow grease to sand through the paint before you actually start to sand the old joint compound. Best of luck...

[dremmel]

If you really want to sand down an area that has paint and joint compound already on it, use a belt sander. I did this once and it takes it down but the belt may get a little clogged and the dust really made me wish I hadn't. Even using a belt sander with a bag attachment is dusty.