Asked on Feb 24, 2014


2 rooms were built onto the back of our mobilhome they are made out of cinder blocks we keep getting mold in the winter months really need some help on what to do to resolve this problem ?
  10 answers
  • Shellley, mold needs moisture and food to grow. Is the cement block painted? If so, the mold is growing on the surface of the paint. Its the food it needs to grow. Simply clean it well using a good bathroom cleaner. Not bleach it does not work as well as you would think. Once dry repaint using a paint that has an anti-microbial additive to it. The bigger issue you have is the moisture. Until you can identify the source of the moisture on the block, the mold will continue to come back. Stop the moisture, you will stop the mold. If you have a way to post one or two photos of exactly what this mold looks like and perhaps one of the room itself. I may be able to provide you with additional information about this issue. What color is the mold and what does it look like? Is it white and powdery looking or is it a dark color that is staining the finish on the wall.
  • Laurie M Laurie M on Feb 25, 2014
    Clean with a good bathroom cleaner (esp one for mold.) Seal it with a good masonary paint. Paint with a mold preventer in your color choice. I used Kilz Paint tinted in my desired color. You'll want to make sure it is sealed from the outside too.
  • Teresa Church Teresa Church on Feb 25, 2014
    Do NOT use bleach products! use a good product for Black Mold, and do not use one that you spray as when you spray these spores will travel and can and will get into your lungs and grow, they will cause severe health problems and even death. Make sure that you use a good mask that will not allow spores to travel through. you can check out what will work for black mold on the CDC website. please be careful as I lost a very good friend at an early age because of black mold.
  • Laurie is right. Clean with anything you want it only matters that you remove the spores and mold using a damp towel or sponge. You can then spray something to sanitize and bleach works great. Just be sure to use the bleach at a diluted level about 20% bleach to water. At that point you need to seal the surface of the cinder block on the inside and the outside. Any product designed to seal the block will work. Lastly it is a good idea to paint the surface after it has had a while to dry. Woodbridge is kind of right in that there needs to be moisture but if moisture is on the block for an extended time then a biofilm will develop on the surface and mold will grow on the cinder block just fine. There has been a lot of confusion regarding bleach with mold because of poorly trained techs in the water damage business. Bleach kills mold and actually destroys the cellular structure of the mold rendering it less of an allergen after exposure. But bleach is only temporary and will not continue to provide any protection against the return of mold. You will need to solve the moisture issue for a long term solution. The other potential issue with bleach is that it is a skin and eye irritant so be careful. also bleach used too heavily will leave a residue that will cause issues later for the surface that is treated so clean up the surface after use of bleach.
  • Gail lichtsinn Gail lichtsinn on Feb 26, 2014
    Bleach will kill some of the spores and bleach it so the mold doesnt show but pure white vinegar will kill it.There right about spraying it will put the spores into the air
  • Need to clear some things up about bleach and mold. Bleach that you purchase over the counter even that stuff that says for mold, is not nearly strong enough to kill many molds that are found in some homes. The bleaching action of the bleach fools people into thinking that they are killing the mold, however all its doing is bleaching the color out of it. The bleach that professional remediation contractors use, when they do use it, is much stronger then you can purchase over the counter in a big box store. Its never ever diluted with water. Water is what caused the mold in the first place anyway. This is not to say not to use bleach, but that is only part of the equation when it comes to removal. Vinegar will not kill many molds also. While vinegar does amazing things, its not one of them. If you google mold cleaning chemicals you will find bleach as one of the top suggestions. However I can tell you from my experience its not the cure all for this. And most of these sites are simply people either trying to sell something, or someone who believes in that method without any real science to back it up. I spend a few hours every week on boards that those who are in this industry such as I, that talk about methods to clean and remove mold and the latest science in the industry. Ask any of these experts and I am far from one compared to most of them. And they will tell you the same thing. Bleach will not work in many cases of mold removal. Ideally chemicals that do work well are those that are designed to clean tile and bathrooms. Other chemicals that are used in this industry the public simply is not allowed to purchase without having a license to handle pesticides. AS far as spraying, your part right and part wrong. Using a spray bottle of bleach or any liquid for that matter will do little to disturb the mold and cause it to go airborne. AS soon as the spores are wet down, they stick to themselves. We use garden sprayers all the time when we remediate mold from a surface. But we also contain the area using plastic and air scrubbers keeping the area under negative pressure so if any mold does go to the air it is drawn into the filters then the air is harmlessly sent outside of the building being worked on. What you do not want to use is a spray that would come from a can under pressure. It simply does not wet the surface fast enough and because the spray is under pressure, which is much more then the pressure from a hand spray bottle. It can blow the spores off into the air before enough moisture contacts the spores making the stick into place. Always, always use the proper respirator when working around mold. While a N-95 mask which is that white one you see in most paint stores is ok for small jobs. You should be using a properly fitted face mask that has been fit tested to assure there is no bypassing of the breathing air. We use air powered filtered air systems that use air that is located outside of the area in which we work. These masks are full faced covering our eyes nose and mouth completely. You can get some real good infections in the eyes if mold spores are bad enough and in high enough concentrations and come into contact with your eye. These concentrations have nothing to do with how large an area is that has mold on it. You can get a simple square inch of mold and have over 20,000 spores or more in it. It all has to do with what your dealing with and how long the mold has been established, lastly complete removal of drywall with replacement of new is the only tried and true method of mold removal. 99% of the time the mold on the other side of the wall where you cannot see is worse then what you cleaned up on the front.
    • See 1 previous
    • Mark Bailey Mark Bailey on Nov 15, 2020

      Thank you for the good advice.

      I was thinking about spraying block wall with liquid pool shock to kill the mold and then use a pressure washer to spray off. Any thoughts? How long does chemical need to stay on the wall before washing off?

  • Tonya Tonya on Aug 01, 2015
    Jesus Christ!!! I am floored. Thanks Woodbridge, you are very generous and helpful with your professional information. I have really learned a lot...I appreciate the free information. Bless you😘
  • Joe Joe on Jun 06, 2018

    Almost any soap or sanitizer can "kill" or render mold spores nonviable. The key is to scrub most of the growth off the wall and of course stop the moisture source

  • Jody Herman Jody Herman on Jun 06, 2018

    Spray Clorox repeatedly and ventilate. Mold loves warmness too so make it as cold as possible

  • Carl Dowlen Carl Dowlen on Sep 01, 2019

    I also have this problem in my home. The moisture comes from condensation (esp. winter months) from the outside beingso much colder than the inside. I simply have a fan that blows down the side of the wall and for the most part it has decreased the amount of moisture being created by the condensation.