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Bathroom Ceiling Paint Peeling + Mildew + Cement Board

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  #1  
Old 01-21-10, 08:00 AM
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Bathroom Ceiling Paint Peeling + Mildew + Cement Board

I have a washroom where the ceiling has its paint cracking and peeling in addition to dark mildew and mold patches... In addition, after it peeled, it seems that it is a cement board behind it on the entire washroom ceiling. Also, there is a .5" hole due to some water damage in the past (water was flowing from it, roof has been fixed now).

I do not wish to put tiles on the ceiling, how can I repair all this?

To summarize:
- Need to repair washroom ceiling
- Paint is peeling and mold/mildew everywhere on the paint (black dots spreading)
- Cement boards everywhere, one damaged with a hole
- Do not want to tile, want a clean flat finish
 
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  #2  
Old 01-21-10, 10:06 AM
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Cement board like Durock or tile backer board?

If it is truly cement board then are the joints taped and finished?

The cement board is tough enough that you should be able to scrape off everything that is loose then scrub it with a bleach solution to kill the mold.

Then let it dry and use a setting type of joint compound. It is more durable and a little more moisture resistant than ordinary.

Get some ventilation to get the humidity out of the room.

And maybe you need more insulation in the ceiling to help keep the ceiling nearer the same temperature as the room to prevent condensation.
 
  #3  
Old 01-21-10, 02:40 PM
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How old is the house? could the cement board be a plaster base coat?

Once the walls/ceiling is repaired and primed, use a good kitchen and bath enamel. K&B paints have more mildewcide and are formulated for the harsher conditions in a bath rm. Zinnser's Perma White would be a good choice if you want white or a light pastel.

An exhaust fan is best but even leaving the door open after a shower will help a little to remove the moisture.

almost forgot
welcome to the forums!
 
  #4  
Old 01-21-10, 02:53 PM
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If what the OP thinks is cement board is indeed plaster brown coat then the solution is the same. I'd probably use whitecoat or Keene's cement if I could get it but neither of those is amateur friendly so I think a few coats of EasySand would still be the best.
Grind the first one in pretty tight, then give it a second coat and probably then a third as soon as the prior coat sets.
 
  #5  
Old 01-21-10, 07:35 PM
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@tightcoat: To be honest, I am not sure anymore... It came from a really old house, maybe 50 yrs? two story duplex, no hvac, just electric baseboards. As for the joints, assuming it is cement boards, you mean between the boards?

We have fixed the ventilation issue, there is a vent now but I feel it is not powerful enough, any tips for checking that?

@marksr, @tightcoat, what do you think seeing a picture I took just now?

http://ptcls.net/tmp/Bathroom-Ceiling-01.jpg (let me know if you need higher resolution)

Thank you!!
 
  #6  
Old 01-22-10, 04:20 AM
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That looks like plaster to me. I'd scrape off what I can of the plaster [leave the base/brown coat] and then apply durabond - but tightcoat is the plaster expert so use his advice
 
  #7  
Old 01-22-10, 07:16 AM
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As MARKSR said use Zinnser's Perma White bathroom paint. It will keep the mildew away for years. Before you do anything including plaster wash it down with bleach.
 
  #8  
Old 01-22-10, 10:15 AM
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Yes, it looks like plaster with a smooth finish. In a bathroom the finish could be Keene's cement or it could be whitecoat. The base coat might be pretty deteriorated too. If it is soft and you can rub it off with your hand then it should be replaced. If the brown coat is still good and hard then scrape off everything that will come off. The paint might come off the finish and the finish might come off of the brown. If most of the finish comes off then get the rest of it off. If the brown coat is still sound a plasterer should not charge much to put on a new finish.
If you can't find a plasterer my suggestion of a few coats of EasySand is still good.

As an alternative, you can put new drywall over what you have. Use screws long enough to go through the drywall, the plaster, the lath and into the joists at least an inch. To do this find the studs by driving a nail into the ceiling until you hit the joist. Do the same on the other end then snap chalk lines across so you know where to put your screws. Finding the first joist is the hardest. After that they should be 16" on center. If you find the joists are 24" o.c. consider 5/8" drywall and use adhesive to help hold it flat. This is a ticklish call because you are adding weight to the joists. In a span as short as a bathroom they should be able to handle it.

Let us know what you find.
 
  #9  
Old 01-22-10, 12:01 PM
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Ok, so if I understand, there is paint (white with mold) over a smooth finish plaster (yellow orange) on the brown surface.

The brown surface can be Keene's cement or some base coat.

What I will do this weekend is to take a paint scraper and scrape off the smooth finish plaster along with the paint and see the condition of the brown coat.

I just bought a stud finder as well.

Any of you have an architectural diagram of how a plaster is joined to the joist? I'm a bit puzzled right now.

Sorry if I sound n00bish, I'm still new to this!!
 
  #10  
Old 01-22-10, 02:00 PM
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Wood lath is the most popular. Basically it's thin strips of wood nailed across the studs/joists. The base coat of plaster is applied over the wood with some of it forced between the cracks between the strips. That locks the plaster to the wood and the next coats of plaster bond to the base coat.

Sorry, I don't have any diagrams
 
  #11  
Old 01-22-10, 04:59 PM
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No, the brown coat is gypsum plaster.
White coat is gauging plaster mixed with lime
Keene's cement is usually mixed with lime it is a little more durable and more water resistant than whitecoat and was often used in bathrooms and kitchens in the days of plaster.

If your house was build after about 1950 it probably has gypsum lath. It is sheets that look similar to drywall. it is usually 3/8" thick, (That is all I've ever seen, though I understand it was made in 1'2" thick sheets too. It is 16" X 48".)

Wood lath is like marksr described. If you have wood lath and if there was a leak it probably loosened the plaster. That 50-75 year old lath was dry as a dead bone and when it got wet it swelled, twisted and buckled and broke the keys that hold the plaster. If this is the case you should consider taking the plaster off. You can remove the plaster, leave the lath, screw new diamond mesh metal lath or woven wire lath to what is there. Screw it to the joists. It's less messy to screw it than to nail it. Then plaster. This is not an impossible task for an amateur and the room is small enough you can probably handle it.

More amateur friendly, however, is to drywall it.
 
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