[compiler]

I found water stain on the laundry room ceiling. Then I went to the attic room to check the other side of the ceiling board and saw it is due to the pipe joint leaking. I can have the pipe joint glued but am not sure what the material I should use to repair the ceiling board from the other side that it has black mold due to the wet. Now the ceiling board has been dry but I need to fill and patch the ceiling board from the other side. Can you tell how to repair the ceiling board from the other side due to the wet? Thank you.

[joecaption]

First thing I notice is there was no primer used on the PVC joint. (there should have been a purple stain on the joint where the primer went on)
There is no just filling that section that's molded up. You need to pull back the insulation and remove any that got wet, stab a drywall saw down through the drywall in 4 places to mark where to cut the drywall, then go below and cut out that section of dry wall and replace it.

[compiler]

Thanks for reply. I do not want to cut and replace the ceiling board because it is complicated and I am unable to do it. The water stain is not very visible on the ceiling board in a laundry room on the first floor. I just want to patch it where the black mold has damaged the ceiling board paper from the other side. I do not know what material is used to make the ceiling board. Is it the same as the drywall board? I saw three repair materials from the HD. Do you think which one is better to patch the ceiling board from the other side?

[joecaption]

Most likly just sheetrock, if you do not replace that area the mold will just keep growing and spreading. You can try and play with it and patch it until the cows come home from below but it will never be right until you cut it out and replace it.
Once the paper below gets wet there is no just patching it.

[compiler]

The mold is just on the paper. If I cut and remove the paper, the black mold will not be seen. Since the material under the paper was ever wet (but no black mold), it becomes a little soft in the surface. So I intend to remove the soft material and then use the joint compound to fill and patch it. After that, I will use the paper tape to cover it. Is it doable? By the way, is the ceiling board gypsum board? Can you identify it?

[nealtw]

You can try anything you want but sooner or later you will want to take Joe's advice and remove and replace.

[joecaption]

Once you cut out the paper from below all you will have is a hole in the ceiling surounded with gypsom mush and mold.
Taping Drywall Step by Step Instructions - How To Tape Drywall

[Master_Class_Drywaller]

If you can see the water stain on the ceiling from the laundry room there was more water damage done to more than just the paper. As previously stated I highly recommend cutting out the section and replacing it. If you have smooth ceilings it would be easier than textured ceilings. If you want to risk it than I recommend picking up a product called "Kilz" and applying it to both sides of the drywall and then repaint the ceiling. I wouldn't worry about repairing the side in the attic if the board isn't crumbling and once you have applied the Kilz.