best way to remove mildew/mold from bathroom ceiling

Charlotte C
by Charlotte C
  15 answers
  • Charlotte, I would first detect the cause of the mold on the ceiling, it may be 2 things 1. A roof leak 2. Insufficient exhaust in the bathroom. If the mold is like small spots, dots etc? This could be a cause of excessive humidity in the bathroom, replace your exhaust. I suggest you place another exhaust above the shower. An exahust of 100 CFM is required for a 90Sf bathroom. If the mold is caused by a leak in the roof, the stain is usally big. Get this fixed asap. Kiltz is a good paint to paint over dark spots and stians. Hope this helps!
  • To add to the mold concerns in bathrooms. Fans are great idea, or just open window when taking shower. brrrr in winter. Be sure if you add a bath vent that it vents outside of the house and not just into the attic or joist space. Also be sure to use insulated venting pipe and pitch it if possible towards the outside of the house. The colder attic temps in winter will condense the water vapor in the pipe causing it to run back into fan and causing it to drip water or in some cases fill the vent pipe to a point in which the air flow will be restricted and not work. What really causes this mold on ceilings to start growing is poor insulation in attic or above ceiling area. The cooler ceiling temps allow the warm moist moisture from the bathroom to condense on the ceilings. If the ceiling was properly insulated you will slow down and perhaps even stop the mold from growing on it.
  • Tom S Tom S on Jul 21, 2011
    I had some success (e.i., It lasted 3 years before we moved) with a 3-step approach: 1)cleaning the bathroom ceiling with a bleach solution and then repainting with a mildew-resistant bathroom paint. Since mold actually eats into the paint and wall (and bleach only kills surface mold), I could not remove the faint outlines of where the surface mold was prevalent. So I repainted with an anti-mildew additive in the paint in an attempt to encapsulate and retard recurrence of the surface mold. 2) Adding a roof-mounted attic ventilator fan triggered by both temperature and humidity levels to remove excess humidity above the bathroom ceiling . 3) Banging on the bathroom door mercilessly whenever I heard my kids taking a shower without using the bathroom ventilator fan!
  • Charlotte C Charlotte C on Jul 22, 2011
    thanks to everyone who replied! I dont have a bathroom window. I will have the exhaust fan checked. Hopefully it isnt an insulation issue(=MONEY) but i can get someone to check that as well.
  • Charlotte, I doubt if it is an insulation issue. Add the exhaust and check for roof leaks, Good Luck and I hope you get this fixed soon.
  • SawHorse Design Build SawHorse Design Build on Jul 22, 2011
    Find the source of the mold first and stop the condition that is causing the mold. 1. If it is around an HVAC vent, then it is coming from condensation around the metal boots in the attic. This happens when it is humid in the attic and the ducts are cold and not insulated. The cold ducts cause the water to reach "due point" and the water comes down through the Sheetrock and causes mold to form since it is eating the paper on the drywall. 2. If it is in the shower- make sure your exhaust fan is properly sized. If it is, then put it on a timer and let us run for about 10-15 minutes after you take a shower. This will help relieve the space of the extra moisture from the shower. 3. If is appeared in the winter time- it could be because of lack of insulation in the ceiling. The cold air in the attic cause the moisture to form on the ceiling on the inside (this time). Can you let us know when it formed and where?
  • mix one part peroxide to a gallon of water and spray over area!!
  • Leslie D Leslie D on Jul 22, 2011
    The exhaust fan needs to run for 15-30 minutes after you shower. Turning it off as you leave the room doesn't provide enough ventilation to rid the area of moisture. A great idea is to put the fan on a timer, so that it runs a while after your shower.
  • as bleach evaporates it quits killing mold/mildew, however , as peroxide evaperates it leaves a whitish / clear residue and continues to kill,,, then simply repaint priming with a kiltz brand ,, you can get it in an odorless and repaint in desired color!!!
  • High humidity in the room is the most likely culprit. Put the fan on a humistat type switch that keeps the fan on until the humidity is back to normal. Another very common problem is improperly installed ductwok from fan to exhaust vent. It should e sealed with foil tape at joints and should slope down to the exterior of the house. I can't count how many times I have seen duct work that allows condensate to puddle in the pipe and then leak back into the house. Sometimes there is ducting that never got hooked up. Best choices is bath exhaust fans are the remotely installed ones such as made by Fantech or Panasonic. They hang in the attic rafter space separated from the bathroom ceiling by a few feet of duct so you never hear the sound. Noisy fans mounted directly in the ceiling bother people, so they fail to use them and let moisture build up. Another potential concern is that a bathroom should have the door installed such that there is a bit of a gap under the door for air exchange, esp in a home with ducted air HVACsystems
  • Cleaning chemicals such as bleach, peroxide and the like will clean off the surface issues. But will not prevent mold from returning. Nor will it remove any mold development within the surface of the wallboard. Using anti-microbial paints, primers, will not stop mold from returning, only aid in prevention of it from rooting into the surface of the material. Forget using the additives to paint, simply does not work and can alter the quality of the finish if not compatible with paint used. You must remove the moisture from the room. The time the fan runs, is dependent on the CFM of the fan itself . Where the fan is located is simply a matter of choice but I agree the ones installed remotely are the best both in volume and noise control.
  • Woodbrdg, You apparently have a lot of experience with this. What is the best product to use to wash down a mildewed surface inside a home if it is a recent thing?
  • Nichter's This would depend on the surface. But if the recently mildewed surface is hard, any good quality over the counter cleaner would work. If the surface is soft such as drywall and it wipes off using over counter cleaner your OK as well, but if there is any evidence of stains left over your best to remove damaged stained material and replace. One factor is to be sure that the mildew is on only one side and that it was not the result of something else from the back side that has grown through.. The bottom line is to check see if the surface is dry and where the moisture came from that resulted in the mildew in the first place and fix that. Still another factor is the area that is effected. A small wall section or ceiling can be done with over counter chemicals. If you have a much larger surface then chemicals that are EPA approved should be used. and using these requires that you are licensed as a commercial applicator.
  • I see OTC cleaners with sodium hypochlorite claiming to be able to treat/remove mildew. Then I read labels and see the active ingredient varying from .5% to nearly three percent. Should one assume that more is better?
  • Peace Painting Co., Inc. Peace Painting Co., Inc. on Jul 28, 2011
    Any of those concentrations will kill the mildew, the stronger ones start working on the stain. As long as the stain is not too dark, it will be alright to paint. Rinse the area well of any hypochlorite or bleach as these products will destroy the mildewcide additives in the finish coat.