My house is a 50 year old two story home built with textured dry wall ceilings and copper pipe. My upstairs bathroom is directly above the kitchen, and I developed a pin-hole leak in a pipe, which caused a wet spot in the corner of my kitchen. I had a plumber come in to repair the pipe. He cut out a small hole above the leak to find hte problem. Since I was on well water and have had a few other leaks over the last few years, he recommended I replace the copper pipe to the sink and bathtub with Pex. I agreed, so he cut out about a 10 ft long x 3 ft wide piece of sheet rock to replace that run of copper. When removing the sheet rock, he followed a ceiling beam running the length of the kitchen. To put up new sheet rock, he screwed a 2x3 strip to the existing roof beam to secure the sheet rock to. He then had another guy come in and texture the ceiling.
The problem was the new texture didn't match the original texture at all, and it's very obvious there has been repair work done there. I've been removing the popcorn from my upstairs ceilings for a couple of years, so I decided to go ahead and remove the texture from the kitchen ceiling and paint. After scraping the texture, I didn't like what I saw. The plumber cut the sheet rock parallel to a wood beam, but the original piece of sheet rock ended on the same stud. He had put new tape over the original taped seam, making it high there. When I removed the new tape, I found I have a thin strip of sheet rock about 3/4" wide (the remnant of the piece he cut out) between the original sheet rock and new sheet rock he installed. The guy also didn't do the best job of cutting the old sheet rock. The area he cut out must have been out of square because there were gaps up to about 3/8" wide at opposite ends of the new piece he installed. He just filled that with mud and applied a standard piece of tape. I've removed all of the new taping and have questions about how to best prep the new joint. One of the other things I noticed was the original sheet rock mud is harder than the new sheet rock mud.
I need to re-tape this joint and would like some thoughts on how best to repair this. Here are my questions:
1. I found 6" adhesive fiberglass tape for sale. I've used fiberglass tape to repair small holes but never to tape a seam. I haven't seen any wide paper tape. Would you recommend using the 6" wide fiberglass tape along the seam? What about putting down the fiberglass tape first, then applying paper tape over that? I know it will be a little high at the seam, but I think I could make the seam wide enough to hide the added thickness. Can you use fiberglass tape alone, no paper tape?
2. I noted there was a definite difference in the hardness of the new and old sheet rock. I tried using a wet sponge to remove the sheet rock on the original joint without much luck, so I'm guessing I will sand it off. I've already pulled off the original tape and the new tape. I have an oscillating tool with a sander head, so I was going to use that to remove excess mud without damaging the original sheet rock. Is there a better way to remove the original mud? I was planning to put a thin layer of new sheet rock over both joints before applying new tape. The original taped seams are fine, I will just add a little sheet rock to smooth if necessary before painting.
3. I talked about using fiberglass tape with adhesive backing, but I don't think that will adhere very well to sanded mud seams. Would it be a good idea to put a coat of primer over the sheet rock before applying the new tape and mud?
This repair is directly over top of the sink and counter top in the kitchen. I'd like to fix it permanently so I don't have to deal with repairing cracks down the road. I'd appreciate any advice you guys can offer. BTW, I've done a fair amount of drywall repairs and have re-taped a couple of seams in walls, but I've never tried to re-tape a mixture of new and old sheet rock.