Hello there, Jacob here, (from Jacob's Ladder of course)
Do you have cracking and flaking paint on your bathroom ceiling as shown in the above picture? Without proper ventilation, moisture builds up every time you take a shower and does damage over time.
Especially if the ceiling is not well sealed and protected with the right primer, paint, and caulking.
The first step you need to take is to fix any ventilation problems in the space. An old ceiling fan that needs to be replaced, a fan that needs to be cleaned out, or creating a space to install a ceiling fan are all possible options. If you don't have a ceiling fan in your space and you absolutely don't want to install one, you can just make sure that you crack a window while you shower to prevent moisture build up on the walls, although this is not the ideal option.
Once you know that the ventilation is correct, then you can start the process of removing the old flaky and cracking paint. You can do this with a 1in.- 5in. putty knife, or with my personal favorite tool, the "5 Way" (shown below). This tool offers a bit more strength and sturdiness to your scrapping.
As you scrape, you may tear at some of the drywall paper; try to keep those tears as small as possible.
Now, some of the paint may still be okay to leave on. For example, in the before picture of this project, (below) you can see that I did not scrape to the very edge, this was because the paint around the edges was not flaking or peeling. The paint that was along the sides was still in good shape and was much more difficult to scrape off, so there was no need to do the extra work by taking the sides off as well.
Once all the scraping is done, you want to take some 150 grit sanding paper or a medium strength sanding block and run it over the whole area to make sure you knocked down everything that is loose. Make sure you sand the torn drywall paper areas extra well to minimize the amount of paper that is loose.
OK, so you're all done with your sanding. What you want to do next is to use a primer to prime over the trouble areas where the drywall paper has torn. Any general primer will do. The primer will prevent any bubbling in your joint compound when you patch the area and allow the joint compound to have a strong bond.
After the primer, you want to skim coat (a fancy way of saying apply a thin coat) of joint compound to the areas that are still not smooth from the sanding. When I say a thin coat, I mean very thin. Most people tend to lay it on thick, but you want just enough to cover the imperfections, while being able to lightly sand down any ridges when it drys.
For this application you will want to use a putty knife (shown below) Once the joint compound dries you'll need to sand the ceiling smooth one more time.
Once all of this is complete, the real priming must begin. Tape off the tile or walls that you don't want paint on, and if you have it use masking paper to cover the tile as you are more than likely to get some splatter as you roll.
If your shower ceiling gets a lot of moisture exposure and you're worried the same problem is going to come back a few years down the road, then I recommend using an oil based primer to seal that ceiling exceptionally well. This will provide the best protection against any flaking or cracking in the future. The oil based primer has superior water resistance and durability for an area like this. Make sure you are careful with the oil based primer as there are specific care and disposal instructions that you need to follow. It also has a very strong odor so make sure you open a couple windows as it will need 4-6 hours before the smell will dissipate fully.
With priming complete, now you can paint away! Make sure to use either a flat or matte finish for ceilings. Traditionally flat is the best choice for ceilings, but matte has a higher durability and wash-ability rating which is why I used the matte finish on this ceiling particular ceiling. Sherwin Williams offers the perfect paint for a situation like this: Duration with a matte finish, it will last for years to come.
Lastly, you can take down your tape. You will most likely have a few areas where there is a small gap between the tile and the ceiling, to make that disappear run a bead of shower/tub caulking along the edge to seal it up. You do this by squeezing the caulking out of the tube to cover those areas and then smooth out the caulking with either your finger or a wet rag. That's the final touch! Ceiling restored to glory!