Do you wonder why your house gets dusty so fast?

Do you have something like this in your attic?

Do you feel like your house is always dusty, in spite of how much you vacuum and clean? Have you tried all the tricks – HEPA vacuum cleaners, air cleaners, taking your shoes off before coming in the house, washing the dog…. all to no avail?

Chances are good that you’re being plagued by a leaky duct and air handling system.

When you have leaks in your ducts (virtually all duct are leaky) dust from the attic gets sucked into the ducts and distributed throughout the house. Even if you have an excellent filtration system on your air handler, the dust can be sucked in from places that don’t get filtered, and blown into your home, usually leaving fine gray dust everywhere.

Before you call in a heating/cooling (HVAC) contractor, there are a few steps that you can take yourself.

Warning: working in an attic can be dangerous. Many attics don’t have proper floors. Numerous people have taken bad steps and fallen through the ceiling, often resulting in serious injury or death.

Assuming you are comfortable working in the attic and can safely access the duct work and air handling system, here are some things to check:

  1. Ensure that the air filter port is sealed air-tight.
    At least  10% of the systems I see look like the one in this picture. The air filter port is open and an over-sized filter is sticking out the side. Not only does this rob you of 20%-50% of your system’s efficiency(!) and cause the air to get extremely dry in the winter, but it sucks nasty, dusty attic air into the system where it is blown throughout the house. Fix this simple problem  (get the right sized filter and tape over the port) and you will see immediate energy savings and probably a much less dusty home.
  2. the duct "boot" has a big gap

    Check your air registers around your house
    Your home’s air registers should mostly be clean. If some are much dustier than others, this is a sign of leaks near that particular register. Sometimes it will be a leaky duct leading to it, other times it may be the register itself is poorly attached to the ceiling, providing a gap right into the attic. I’m always suspicious when I see a really dusty register.

  3. On a cold and windy day, turn off your forced air system (air conditioner, heat pump or furnace) and see if you can feel a cold breeze coming from any of the air registers in the house. The duct system is supposed to be completely sealed, so you should never feel really cold air blowing in. You might feel cool air drifting in due to the ducts being cold, which causes the cool air to “drop” out of the ducts. But if you can correlate cold air blowing in with wind outside, you’re sure to have leaks. The more of a breeze you feel, the closer you are to the leak.
  4. Poorly attached duct

    Look around the attic to see if any ducts are visibly detached or “askew”, particularly at registers and ducts that failed test #3 above.
    These can be hard to find, but sometimes it’s pretty obvious. All the ducts should be nearly and strongly attached at both ends – where it leaves the main trunk lines and where it feeds the ceiling registers or air returns.
    I’ve seen cases where the ducts have totally fallen off and are just lying on in the insulation.
    Note: special tools and adhesives are used  to connect ducts in a permanent fashion. Do not attempt to repair these problems with “duct tape”! – this tape will fail and you’ll be left with leaky ducts again. Instead, industrial strength zip-ties and tensioning tools are used along with a sealant called “mastic.”

  5. Sometimes problems are hidden in walls
    You might not be able to find any problems in the attic but the problem could still lie in your ducts. Many duct systems run through walls and hidden cavities in your home. It is even common  practice to use naked wall cavities without ducts! Contractors will just pick a wall, ceiling or floor cavity and run air through it. This horrible practice really shouldn’t be permitted because it causes so many problems.
    This type of problem you probably can’t find yourself. A trained infrared thermographer (often an energy auditor or building scientist) may be able to locate the problem, but sometimes it can be very difficult.
  6. Beware of Vermiculite
    Some older homes have Vermiculite insulation in the attic. These homes should not be tested using a blower door or duct blaster and you should not poke around in this material because it may contain asbestos. Not all Vermiculite contains asbestos, but this is definitely a case of “better safe than sorry.”

I started this post saying that you shouldn’t call in your HVAC contractor and I’ll finish it by saying the same thing. Many HVAC contractors are not trained to find these leaks. Think about it – who created these leaky ducts in the first place?

As a building science / energy consultant, I’m biased because I’m an independent consultant, and I recommend that you use someone who is also independent to diagnose your issues. They might fix them as well or they recommend a high-quality HVAC contractor whom they know to do good work. They will also have special equipment like a “blower door” and a “duct blaster” that allows them to quantify the leakiness of your ducts much more quickly and accurately than someone without these tools. In fact, without at least a blower door, it will be very difficult to even find many duct leaks.

Fixing duct leaks can help make your house much less dusty and it has the side effect of making it more comfortable and energy efficient. This is one of those things that you’ll wish you had done years ago because it can make your house more enjoyable to live in every day of the year.


“Why does house get dusty when heat on and not with ac on?”

Occasionally, weird things happen. If you’ve gotten this far, you know that the dust is usually sucked in and distributed by the duct system. If that’s so, then how does the above situation occur?

There one possibility that comes to mind – moisture.

During the summer, the cold coils in the air conditioner are covered with water – this is the summer moisture getting drawn out of the air. When the dusty air moves through the coils, much of this dust could be trapped by that water. This would lead to much less dust when the air conditioner runs than when the heat is on.

“Does an energy audit show why there is so much dust in the house?”

Someone else asked this question. The answer is “maybe.”

If the energy audit is a comprehensive review of your home, done by a competent technician, then yes, the audit should be able to show why your home is dusty. To make sure, you should tell your auditor that you’re having a dust problem and you’d like some help finding out why. If they look confused and don’t suggest issues like the ones mentioned in this post, you should probably find a different auditor!

“Why is the air so dry in the winter?”

What does dry air have to do with a dusty house? Possibly everything!

If your duct system is sucking dusty air in from the attic, it will also suck in the very cold, dry air from the attic. When that dry air enters your house, it sucks up the moisture from your home like sponge, resulting in very dry air. That’s why an uncomfortably dry home in winter is a giveaway that the home is very leaky.

Keep in mind that the dry outside air could be coming from anywhere. If you have leaky windows and doors and a drafty house, it’s also going to be uncomfortably dry. That said, nothing dries out a house faster in winter than a leaky duct system that’s sucking in cold, dry outdoor air.


79 thoughts on “Do you wonder why your house gets dusty so fast?

  1. How can I find a professional who can help me locate the source of the small white particles that seem to be coming from a ceiling vent in the bedroom? I did not even notice it until a few months ago when I put a quilt with a black background on the bed. Despite daily removal of the particles with a lint remover, they come back the next day. I had a hunch they were coming from the duct above the bed, and your column confirms my suspicions. I’m afraid if I call an HVAC professional, they will try to talk me into getting my ducts cleaned, which if I understand you correctly, will not address the source. The house was built in 2000 and has two attics — one over the garage and the other over the bedroom. Thanks for your help.

    • Hi Lisa, if you post your city/state or metro region, I can do a search in your area for companies that look appropriate.
      What I would do is search on something like: duct pressure testing. That will come up with a variety of results, many of them HVAC companies. As you noted, they wouldn’t be my first choice. Instead, I’d look for something like this company (which was one of the top google hits in my region:
      Look for a specialist in duct testing that is independent. I prefer consulting companies over those that are trying to sell a product.

      Hope that helps!

  2. Great article. I would appreciate your feedback, My house of 18 years has a hall intake where filter would normally go. I had a merv11 air cleaner and filter installed for my furnace in the attic. So now my hall intake goes without a filter(told I can’t use a filter in hall as well as the attic). The hall grill that would normally cover a filter is always dirty. I do believe the house is cleaner and vents look pretty good and I can see that the merv11 air cleaner in the attic does collect a lot of dust. Is this conversion from hall filter to attic as good as I was led to believe?

  3. We have all electric heat even when all ground is covered with snow in our area we still get a smoke like film on windows and furniture. No one ever smokes in the house we have three electric heaters with fans in living room and entryway and the balance of the house is baseboard electric do you have any ideas where it’s coming from ?

    • Cooking? I had that issue in my garage where I’d used my fryer. took me a while to figure that out.
      Not sure what your reference to snow outside is. I must be missing something. What are you thinking about there?

  4. I live in my childhood house, almost 100 years old..It is so very dusty, I started with getting the ducts cleaned, I would actually have to dust every day, allergies, eyes burning..Now after they have been cleaned I only have to dust every 2 or 3 days. I am permanently on allergy pills. Who and where do I start looking for someone who can check for leaks?

    • many areas now require duct pressure testing for new homes or major renovations. I would first call your local Building Department and ask if they can recommend anybody who does duct testing. that would be the place to start.
      however one thing you can do yourself is to look at your furnace especially where the filter is installed if it is located on the furnace. often dust is sucked in and spread around the house by the furnace itself. if the unit does not look airtight, that is you can see cracks in the joints where air would easily be sucked in, those can be sealed and can make a considerable difference.
      the difficulty with old homes is that often compromises are made when installing the ducts. sometimes they run air through the walls without even using any ductwork. that can lead to horrible dust problems.

  5. We have had a new AC unit put in, all new duct work, i have hardwood flooring throughout, and crawlspace. The crawlspace does not have plastic on top of the dirt. Could this be causing dust issues in my house? I dust and the next day I have dust again I can’t keep up with it. My son is suffering with awful allergies and asthma just trying to do all I can to help him.

    • Someone might be able to tell you what type of dust it is which could give you a hint as to where it’s coming from. Normally, unless there’s something disturbing the dirt in the crawlspace, I wouldn’t think that it would cause that type of problem.
      If the dust is like fine lint – white dust, it could be coming from insulation getting into the system somehow. Is any part of the system in the attic? If so, what is the insulation like in there? Blown in insulation can be very dusty and if the air system has any leaks, the dust can get sucked in and blown around the house.
      Look at the air vents where the air comes out. If they look dusty/dirty, then you’ve got a problem with the system because those vents should only be passing filtered air. Then look at the air intake vent for the system. If that duct is really dusty, then you’re probably sucking in dust from somewhere else.
      You should also check the main air filter. Does it get dirty fast? Are you using a good quality pleated air filter or one of those horrible fiberglass ones? A pleated filter with a MERV of 8, 10 or higher is recommended as they do vastly better at filtering the fine dust. Those other ones are virtually useless for filtering anything smaller than dog hair.

  6. Wow, this is a huge problem for us. We constantly have dust, with the downstairs registers always coated (no matter how often i clean them). The problem is that we have NO real ductwork – the wall cavities are used as ducts like you describe. AND our attic is full of blown in loose fill insulation (the fluffy white stuff)! My son has asthma – it’s horrible! i am constantly dealing with dust! My question is – are we doomed bc we do not have duct work??

    • Oh, that’s a sad situation.
      It really depends on your budget. The health of your family is of top importance, but I realize that most people don’t have it in their budgets to redo their air distribution system.
      You might be able to focus your efforts if someone in the family is handy.
      Where is the air handler for your system? Is there any part of the system that is in the attic with all the insulation?
      How does the air filter look? It should catch and filter much of the dust if it’s a good filter. If you’re using one of those cut-to-size filters, they’re really no good. You want a pleated, high MERV filter. Look for a rating of at least 8. Preferably a MERV 11 filter. Try this first and see if that improves the situation. If not, I can give you more tips.
      Check out info about air filters at this link:

  7. The home we moved into so dusty. I can dust one day and the next day you can start seeing dust. We have the good HEPA filters in. At least I thought they were good . Please help! Thanks

  8. I am getting what appears to be white type lint that gets in my eyes and face and is giving me headaches.I had a new furnace put in 10 years ago through a government assistant program that did a shoddy job. I am worried. Can I get cancer from this? They would not address this at the time and I had to pay over three hundred dollars to redo all the ductwork,as it all fell apart.I wonder if I am breathing in insulation?

    • I certainly can’t comment on your specific cancer risk. If it’s that bad, you need to have the material tested. In general however, no modern insulation materials have been shown to have serious health consequences. Yes, some are irritants – for example, handling fiberglass leads to extremely itchy skin. Loose fill insulation, the type that’s blown into attics such as fiberglass and cellulose (shredded newspaper) often are very dusty and if the ductwork isn’t well sealed, can be sucked into the ducts and blown around the house which will lead to a dusty house.
      If you have ductwork in the attic or the main system is in the attic, this would have to be carefully examined for leaks and sealed up. This requires someone with a real eye for detail, but anybody can examine it if they can safely navigate the attic. Look for openings around the blower – seams that aren’t sealed air-tight. Then examine how the ducts are attached and run to the vents. Seams should be sealed and/or taped with special materials. Any gaps will be prone to sucking in dust. It’s unpleasant and time consuming work, but your health comes first.

    • I just had the same done in 2016. My entire home is infected. We had to close off the air condition system due to the debris falling from the vents. It’s a total mess. You might want to check your health. We are having a lot of health issues. We have had many Infections in just over a year. The entire home has been infected. I can’t clean any more I get so sick when I try to clean. I can’t get any help from any agencies. I’ve been looking into it for over a year now. There are regulations listed but no one to report them too. The energy program is running all on there own. All of these programs run on goverment money. There is no goverment agencies to report problems too. I wish I knew this before I had them come into my home. I have photos videos of all the damage. They were suppose to prep the attic before installing the insulation, They did not do it they blew the fiberglass insulation into the attic. It was falling all over the house including us and the animals. The fiberglass would cut into my skin then the bacteria would enter into my body . I am covered with sores. Every nook and cranny in my house had debris falling out of it. My walls now have mold growing on them. I have a brand new fridge that has begun to decay on the side where the fibers fell onto it. I have been living in hell. I can’t find a law firm willing to take it unless I pay them a lot of money.

  9. Our furniture is dusty within 2 to 3 days. We had a mold miser put on our unit we have a new heat pump and also had the electric static filter system put on. We do not have any duct work in our attic. What type of company would we hire to look at our duct work?

    • You can start by asking the company that installed your heat pump for a reference to a contractor that does duct testing and troubleshooting. Often this will be an energy auditor. Depending upon where you live, there may be several qualified contractors or none. But that’s a start.

  10. I have many of the problems described in this well-written piece…I just don’t know what my next steps should be. I change my filters once a month. There is visible dust in the air in the morning light in the living room. I have dust on the clothes and jewelry inside of my dresser drawers in my bedroom. After 4 days, I can easily write my name in the dust in both the living room and the bedroom. I can write my name in the other rooms’ dust after 8 days EXCEPT for the “guest house”, which shares a wall with the main house but has its own HVAC system. It does not get dusty for weeks and weeks even though I open and close the door on a regular basis. I had an Energy Audit by a company that does not sell or install HVAC equipment. They did not have solutions, although I was not convinced of their educational background. (I am a Mechanical Engineer…but have not practiced for a while). One last thing. In the summer, there is a cool space in the living room that I cannot pinpoint. Same in winter…a warm space. So…I’m pretty sure that faulty ductwork is the issue. Where do I go for help since my first Contractor was unable to find a solution? I live in the metro Phoenix, AZ area.

    • I’m pretty sure you nailed it. Since the area on a different HVAC system isn’t dusty, there’s a really good chance that you’ve got duct leakage that’s sucking in and blowing dirt all over your home. It’s shame the energy auditor you had in couldn’t determine the source/location of the leak.
      You’ve also noted the room that gets hot/cold. With a thermal camera, it would be really easy to see the source of that issue. It might be related to the dust problem or it could be just another section of duct that’s not sealed well.
      Are your ducts accessible? Do any run under the house or through other areas which could be dirty/dusty?
      When you change your filter every month, is it really dirty? Are you using higher MERV pleated air filters? I like using those with a MERV from 9-12. I get mine from Nordicpure – good quality at a much lower price than the big-box stores.

      Many home testing companies have a device called a “duct blaster” which is used to test for air leaks. I used to do diagnose this type of problem using a duct blaster and a theatrical smoke machine. You blow the smoke into the fan that supplies air to the duct blaster. Then, wherever there are duct leaks, you can see the smoke come out. This is great for ducts that you can see, like in basements and attics. But if the problems are hidden somewhere inside the house, it probably won’t help.
      Hope this helps you track down the problem. These can be really frustrating!

  11. I live in a double wide home I have dogs that are regularly bathed I have DIRT in my home. I have it on my dishes in cabinets its everywhere I can not keep it cleaned HELP

    • Sounds bad! Have someone check your ducts. They’re probably sucking in lots of dust and dirt from under the house.
      Temporarily, you can put filters over the vents where the air comes out for the AC / heater. You don’t want dense filters as that will impede airflow too much, but you can use the mesh filter that can be cut to size. This will also confirm that the dirt is coming from the vents because the filters will get dirty.

  12. I live in a house built in the mid 60’s in Georgia. My heat sources are two 33 BTU Propane, vent free fireplaces, one upstairs, one downstairs. My A/C’s are window units, one 11,000 BTU for the Master Bedroom and Bathroom and two 6000 BTU units in 2 Bedrooms. I don’t have window screens in place so my windows are never open. Despite all of these things, this is the dustiest house that we have ever lived in. We have hardwood floors throughout the upstairs and I cannot keep them clean and dust free. The downstairs is fully tiled but we have a terrible problem with spider and dust-webs. I can sweep and mop and one week later, the dust and webs are back. I have 4 small dogs, all who are non shedding and hypoallergenic, so I am at a loss for what makes my floors, walls and ceilings so dusty all of the time.

    • Often dustiness can be caused by a “leaky” house. Do you feel drafts?
      The spider webs are a sure sign of drafts. Spiders like to build their nests where there is air flowing past because that’s where insects come from. So I would star looking at the windows and doors near where the webs are and work on sealing them up.

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