How to Clean Mouldy Ducts?

Mould is never something to be treated casually because it can cause serious health concerns, notably in vulnerable people such as children, the elderly, the sick or those with compromised respiratory health. If mould establishes colonies in your heating, ventilation and air conditioning system you’ll need to act fast to prevent the spread of it.


 What Causes Mould in My Ducts?


A warm climate like Houston is a key element to mould growth. It also needs high water vapour, so it’s important to check your vents after the rainy season or cold times as the water will be sucked into the vents and condense there. The mould then gets nutrition from things such as dirt,



How Can I Tell If My Ducts Are Mouldy?


Mould spores are usually too tiny to be seen by the human eye until it’s in later stages of colonisation. The first clue is usually a strange, musty smell that you can detect in several connected rooms. If you can see spots of mould around the ducts, vents and on the nearby walls, your mould problem is quite severe and you may need professional assistance.


What Are the Main Signs of Mould?


We’ve already mentioned the main signal, but we’ll mention it again with some other signs you can watch for:

  • a strong mildew or musty smell throughout the whole house or several rooms
  • your eyes, nose and throat get irritated shortly after turning on the air conditioning or walking into an air conditioned room
  • you suffer from allergic reactions like runny noses, water eyes, sore throats or rashes
  • you or your family suffer from headaches that only occur when you’re inside your home
  • you or your family feels nausea, dizziness or general fatigue, but only at home
  • visible mould around vents, ducts, grilles or drip pans


Living in a warm climate such as ours, a musty smell is a key sign that mould could be in your house; never wait for visible mould as by then it will be much harder to properly clean your ducts.


Of course, if the mould problem isn’t severe, then it can be relatively easy to deal with the problem yourself with products you can get from home repair stores or other places. However, the EPA suggests that if your mould problems covers more than twelve square feet, you must call in a professional team to deal with it. Naturally, we agree with the EPA and urge you to entrust your safety to trained professionals.


The DIY Cleaning Solution


While you should use EPA approved mould removal products for best results and effectiveness, there is a fairly effective homemade mixture that will work well on small colonies:

  • one tablespoon of household detergent
  • half a tablespoon of baking soda
  • one cup of water


Alternatively you can use one part bleach to sixteen parts water.




Mould is dangerous and can easily enter your respiratory system or cling to your clothes to be transported elsewhere. On top of that, the chemicals on your DIY mixture could irritate the skin. In order to be as safe as possible you will need:

  • safety goggles
  • a face mask
  • thick, industrial grade gloves
  • coveralls or overalls (if you can find easily disposable ones, that’s even better)


How to Remove and Prevent Mould in Your Air Ducts


  1. turn off the heating/cooling vents
  2. use a wet rag or brush dipped in your chosen mould remover to thoroughly clean the infected area and the areas immediately around it
  3. repeat the process again
  4. dry thoroughly
  5. dispose of all rags in airtight trash bags. The bags should ideally be 6ml or thicker.
  6. use an EPA approved mould inhibitor and apply it to the vents as soon as you can after cleaning them. If you don’t do this, your unwanted mould colony could grow back within a few weeks.


This process is quite time consuming and comes with high health risks. The better answer may be to get a company to help with the appliance removal. Especially if you are in Phoenix. Failure to to dry and protect the area properly afterwards could easily lead to regrowth, making all your work worth nothing. We always suggest that you let professionals like us perform the cleaning with our specialised equipment and products in order to provide your family the safest environment.


What Else Can I Do to Prevent Mould?


If repeated home treatments don’t work, and even professional work failures to completely stop the mould growth, then there are several other preventative measure that you can use. We would actually recommend getting some of these done regardless of mould problems as they can still help save energy.

  1. Replace the heating, ventilation and air conditioning system filters.
  2. Insulate the ducts in order to reduce condensation
  3. Clean the drip pans regularly as they can encourage mould growth
  4. Seal condensation and leaks. Be careful when you do as the EPA generally doesn’t recommend using sealants  except under special circumstances.
  5. Use a dehumidifier and place them near mouldy areas. Drier air in these problem areas will reduce the water vapour in the hair, slowing the spread of mould.
  6. Check the ducts regularly.




It is possible to clean out mould on your own, but we really don’t think you should do this. This is one of the more dangerous things that can affect your home, your health and the health of your guests as well. The secretive, stubborn nature of mould means that you aren’t likely to spot the colony until it’s too late. It’s best to simply call in professional help like Steam Express in Houston and save time and effort.


The company is professional, efficient and offers mould cleaning services amongst others, and we will be happy to help you. Our services are reasonably priced and amongst other things, we can provide same day and next day appointments.