What Does Wet Insulation Smell Like?

Learn all about the reasons for smelly insulation and how it can be fixed

It is a well-known fact that, if you sense a wet insulation smell in your house, then something is definitely wrong with it and you should check it to avoid any serious problems. However, the problem is that people often have no idea how insulation smells when it gets wet!

In this article, we will explain what wet insulation smells like and what to do if you sense an insulation smell in your house.

Also, we will tell you whether insulation becomes fragile and can be ruined if it gets wet, and how you can fix this kind of issue. In addition, you will learn whether insulation has a smell at all and what could be the reasons for its smell (spoiler: it’s not only because of moisture!).

What Is the Smell Of Wet Insulation?

First of all, we want to note that insulation that was properly installed and cured shouldn’t smell bad at all. Even if there is any smell you can sense indoors, at least, it should not be noticeable or too strong. But if your home insulation does emit an odor that you can sense well, there can be different reasons for that.

PROBLEM SOLVED - Nasty Smell in HousePROBLEM SOLVED – Nasty Smell in House

Also, note that different types of insulation may emit distinct odors. In addition, if your insulation was exposed to different kinds of damage, the smell will also vary. Here are just a few most common reasons for smelly insulation and the smells it can emit:

  • Your insulation might be excessively cured. In this case, it will be smelling like roasted sugar (it is very typical of fiberglass insulation!)
  • Improperly mixed installation can smell too. This issue is prevalent in spray foam insulation
  • Improper ventilation can cause your insulation to smell as well
  • Moisture can also lead to smelly insulation. In this case, it will have a musty smell similar to a room that stays unopened for a long time
  • A pungent odor is also a sign of insulation damaged with water. To imagine the smell, think of rotting wood or dirty socks. Sounds gross but this is how it is

But the smell is not the only problem that comes with wet insulation. See, wet insulation can grow mold, which is a way more serious issue! This is why we recommend you check out how insulation smells when it has mold already.

What Is the Smell Of Wet Insulation
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What Does Moldy Insulation Smell Like?

You probably know that mold is hard to see when it has just developed, especially when it is growing in your insulation. This makes it pretty hard to spot and remove. This is why the best way to notice the presence of mold is to define what smell your insulation has.

Moldy insulation gives off a noticeable musty smell. If you don’t know what this smells like, think of the way a poorly ventilated space smells. Also, if you have ever entered a closet you have not opened for a while, the smell it has is exactly the odor that pours from moldy insulation in your walls.

Another way to imagine what this smell is like is to remember the odor decomposing wood or unwashed socks give off. Some homeowners even compare the smell of moldy insulation to the smell of urine!

Moldy insulation is often the result of the extended exposure of your insulation to moisture. When it stays wet for a long time, your insulation could start emitting a smell like one of those we have just described above.

There is another way you can also tell moldy insulation from the air quality of your home. If more than one person in your household complains of the air in your home being damp, you should check your insulation for mold.

This is especially important if such insulation is installed in your attic. If nothing is done to fix the issue, damp air from moldy insulation could lead to allergies or sneezing perpetually your home occupants experience.

What Does Moldy Insulation Smell Like
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How to Deal With the Moldy Insulation?

After you figure out that you do have moldy insulation in your home, the next step is removing it from your home. First of all, you will need to get rid of the moisture source (or sources) that are contributing to mold growth.

The way you do it will depend on the type of insulation you have at home. If you have spray foam insulation, you could take it out and dry it. Also, you will have to brush off the mold. The mold-removing method is simple because spray foam insulation has an inbuilt resistance to moisture.

For those who have cellulose insulation, it may be a bit more complicated to deal with it. Cellulose insulation is organic and absorbs water extremely well. This is why, if your cellulose insulation grew mold already, it is going to be a bit challenging to restore it. Chances are you may have no other solution but to completely replace the insulation!

Now you know what wet insulation smells like and why it can have different odors. Also, you learned what smell moldy insulation may emit, thanks to which you will now be able to define whether your insulation has grown mold or not.

How to Deal With the Moldy Insulation
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Why Does Insulation Develop Smell at All?

Homeowners often wonder why their insulation starts producing odors, and one of the most common reasons they think of is moisture. However, there are other reasons as well and you need to know about them too! At this point, the type of insulation will generally determine why it smells.

Spray Foam Insulation — The Ugly Truth?Spray Foam Insulation — The Ugly Truth?
  • If you have fiberglass insulation and it is giving off a bad odor, it could be excessively cured. If this is the case, your fiberglass insulation could smell like burnt sugar. The good news is that this smell should disappear on its own
  • If you have spray foam insulation that is smelling, it was most likely improperly mixed. It is critical that the mixing ratio is 1:1. If your installer failed and used the wrong proportions, you will have smelly insulation
  • If your spray foam insulation is appropriately mixed but still smells, the ventilation could be the problem
  • Your insulation can smell bad if done wrong. In this case, it will be giving off a fish-like smell
  • Moisture and mold can also cause your insulation to smell. In this case, the odor will be musty, reminiscent of unwashed socks

As you can see, insulation can start developing odors for many reasons. This is why it is essential that you figure out what causes the odor. Like that, it will be easier for you to figure out what method to use to get rid of it.

How to Get Rid of Smell Produced by Insulation?

Insulation may smell differently depending on its type and the way of damage that is caused to it. In the same way, depending on the type of insulation, you will need to solve the problem differently. Wet spray foam insulation, cellulose insulation, and fiberglass insulation all need different treatments.

  • If you have spray foam insulation, all you will have to do to solve the problem is to dry it out since it is resistant to water and moisture. You can use a piece of cloth or a mop to soak up any water or moisture on the surface. Then place a fan near the insulation to dry it faster
  • Cellulose insulation needs another approach. Since it’s plant-based most of the time, it absorbs water quickly. If it’s way too wet, you might need to replace the insulation entirely!
  • Fiberglass insulation usually doesn’t absorb water. What you can do is soak up all the water and moisture on the surface, and then dry it out with a dehumidifier

However, if the water damage remains untreated for a long time, mold will start growing on the surface of your insulation. In cases like this, your water-damaged insulation will have to be removed and then replaced. Do not leave it unattended since it might be a health and safety hazard!

How to Get Rid of Smell Produced by Insulation
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How to Prevent Insulation From Smelling?

If your insulation smells, no matter what type of it, the best and the most efficient way to deal with the problem is to replace the smelly insulation. But since this often costs a lot, you might want to search for other ways to eliminate the odor. The more financially-friendly way would be to prevent the bad odor in advance. Here is how this can be done.

Reduce Air Pressure Around the Smelly Insulation

One of the solutions is to decrease the pressure in your attic. This involves transferring fresh air into the attic without a corresponding air transfer from the attic into your inner space.

You can do this by installing an exhaust fan in your attic. This solution will not necessarily stop your insulation from smelling. Instead, it will change the route of the odor from the insulation, preventing it from entering your living space.

Reduce Air Pressure Around the Smelly Insulation
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Keep the Ducts Shut Off

If you have HVAC systems in your attic with smelly insulation, you must investigate the ductwork. See, chances are high that the HVAC system could be transporting the smell from your attic into your rooms. So to keep the smell away, you could simply shut off your HVAC ductwork. If you have other ducts that might be leaking, make sure you shut them off too.

Upgrade Your Air Filter or Opt For Home-Based Odor Absorbers

Getting a more powerful air filter in your home can also help you eliminate the odor your insulation produces. You could use activated carbon filters, for example. Such filters can trap over 99.9% of contaminants, keeping off the smell.

Also, don’t neglect simple homemade DIY solutions that can be effective in eliminating foul odors from smelly insulation. You may want to try combinations like baking soda, coffee grounds, lemons, and distilled white vinegar to eliminate odor. Besides, this can be a good option if you don’t want to or can’t use any chemical eliminators.

Upgrade Your Air Filter or Opt For Home Based Odor Absorbers
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How Soon Will Insulation Smell Disappear?

At this point, you might be wondering how much time you will need for getting rid of the insulation smell in your house. Well, it depends on whether we are talking about freshly installed or damaged insulation. If you have just installed it and it smells, insulation odor should naturally deteriorate pretty quickly. Usually, your insulation will eventually stop smelling within 24-48 hours after installation.

If your insulation still smells by the third day after installation, something is wrong. When the insulation smell stays that long, chances are that there is something wrong with the ventilation or there are other causes for the bad odor.

So, now you know way more about smelly insulation! We told you what wet insulation smells like and what the odor could be under other circumstances.

In addition, now you know that different types of insulation e.g. fiberglass, foam, etc. can smell differently. Also, you learned how to prevent foul odors from your insulation and how soon the unpleasant smell (if it exists) will disappear.

How Soon Will Insulation Smell Disappear
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Frequently Asked Questions

⭐Can old insulation make you sick?

Old insulation can make you sick if it has mold. In this case, it has to be replaced.

⭐How much does it cost to replace insulation?

The average cost of home insulation is between $3.000 and $10.000 for a 2.000 square foot house.

⭐How soon does mold grow on insulation?

Usually, mold takes up to 48 hours to start growing after water has been left on a surface.

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Melinda worked as an art consultant and Home Designer for eight years in total. As an art consultant, she was first employed in a local art gallery in San Francisco where she was responsible for picking the most suitable artwork for her clients depending on their goals and budget. At this job, Melinda showed herself as a confident specialist and a true art lover with exceptional taste and artistic sense. Melinda is a passionate author of Housekeeping Bay and we are really happy that she is our Expert.
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