Does Insulation Have a Smell? (Explained and Solutions)

Home insulation is designed to deliver premium air quality inside your home. Home insulation is expected to keep indoor air healthy and comfy by shutting off contaminants. But what if you begin to notice a smell from the insulation itself? Does home insulation naturally have an odor, or is something else wrong?

Properly installed and cured insulation doesn’t smell bad — or at least, not notably. If your home insulation does, chances are it was excessively cured. Such odor – smelling like roasted sugar – could proceed from the insulation batts, typical of fiberglass. Improperly mixed installation can smell too. The latter is prevalent in spray foam insulation. Also, an insufficiency of ventilation can cause your insulation to smell. Soaked moisture can cause smelly insulation.

Insulation smells can be noxious, making fixing such faulty insulation a priority. What can you do to remedy the situation? How long does it take for the home insulation smell to go away? These are some of the questions we answer in this guide.

Why Does Insulation Smell?

The type of insulation generally determines why it smells. First, if your fiberglass insulation is giving off a discomfiting odor, the chances are it was cured for too long.

When excessively cured, your fiberglass insulation could smell like burnt sugar. This should, however, go off on its own.

If your spray foam insulation is smelling, finger should be pointed at the mixing ratio. How properly did the installer mix it?

Here is it. When spray foam is procured, the manufacturer commonly delivers it as distinct chemical packages. The installer’s role is to properly mix them before he sprays the insulation into your home.

The mixing ratio is critical. 1:1 is the recommended mixing ratio.

Your insulation can smell badly if done wrong, commonly giving off a fish’s smell. This is prevalent when such an improper mixing ratio handicaps the spray foam from curing properly.

If your spray foam insulation is appropriately mixed but yet smells, the problem could be with the ventilation. It is possible the installer didn’t adequately vent the installation site.

This traps the gas the spray foam emits after being installed. Consequently, such gas would be dispersed into your home, fouling the air.

Moisture and mold can also cause your insulation to smell. We will look more into this down the line.

What Does Moldy Insulation Smell Like?

You rarely see mold, especially when it is growing in your insulation. Your best guess is to investigate the smell your insulation emits.

Predominantly, moldy insulation gives off a musty smell. For those who don’t know what this smells like, it is like the stench of a poorly ventilated space.

This is similar to the smell that pours from a closet you have not opened for a while. This means the air inside is stale, having not been refreshed in a while.

Moldy insulation often results from the sustained exposure of your insulation to moisture. When wet for long, your insulation could emit an unsettling smell like decomposing wood.

This closely mirrors the odor unwashed socks give off. Some homeowners have even complained of moldy insulation smelling like urine.

This indicates water has damaged your insulation, necessitating immediate drying out or replacement.

You can also tell moldy insulation from the air quality of your home. If more than one person complains of the air in your home being damp (even with your house being adequately ventilated), you should investigate your insulation for mold.

This is especially if such insulation is installed in your attic. Such damp air from moldy insulation could result in your home occupants experiencing allergies or sneezing perpetually.

Eradicating the Moldy Insulation

The next step is ridding your home of such moldy insulation. Primarily, you will need to get off the moisture feeding the mold growth.

This depends on the type of insulation in question. If you have spray foam insulation, you could take it out and dry it. This would be followed by brushing off the mold.

It is this simple because of the inbuilt resistance of spray foam insulation to moisture.

For cellulose, it may be a bit more complicated. Cellulose insulation is organic and readily drinks water.

It is a bit challenging to restore cellulose insulation with mold, mainly if it has absorbed substantial amounts of moisture.

You may be forced to completely replace the insulation.

How to Get Rid of Insulation Smell?

Replacing the smelly insulation would be the most natural way to eliminate the foul odor it emits. But this often costs a premium, necessitating you to find other ways to eliminate the smell.

The more economically friendly way would be to prevent the bad odor from the insulation from being distributed into your home. Here is how to get this done.

Reduce Air Pressure Around the Smelly Insulation

Let us imagine the insulation you deployed in your attic smells. You could resort to decreasing 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.

This is achievable by installing an exhaust fan in your attic. Such a fan can be instrumental in dispersing congested air from the attic outdoors while introducing fresher replacement.

This solution will not necessarily stop your insulation from smelling. Instead, it reroutes the destination of the odor from the insulation, ensuring it doesn’t enter your living space.

Shut off the Ducts 

This solution is relatively exclusive to those with HVAC systems installed in your attic. If you have such systems in your attic with smelly insulation, you must investigate the ductwork.

The possibility is high that the HVAC system could be thrusting the smell from your attic (courtesy of your attic air) into your living space.

So if you don’t want the smell to permeate your home’s interior air, you could simply shut off your HVAC’s ductwork. If you have other ducts that are likely leaking, shut them off too.

This prevents the downward dissemination of air from your attic into your home.

Upgrade Your Air Filter or Use Home-based Odor Absorbers 

If by now the smell from your smelly insulation is yet profusely pouring into your space, you may consider getting a more powerful air filter in your home.

Since the emphasis here is to eliminate the foul smell from the insulation, you could go with activated carbon filters. Top activated carbon filters can trap over 99.9% of tiny contaminants, keeping off the smell.

We have seen homeowners leverage scented candles or plug deodorizers into their electrical sockets. But this could be a step too far.

Way simpler home-based DIY solutions can yet be effective in eliminating the odors of smelly insulation. Combinations like baking soda, coffee grounds, lemons, and distilled white vinegar efficiently eliminate odor.

How Long Does It Take for Insulation Smell to Go Away?

Ordinarily, insulation smell should naturally deteriorate (and eventually stop smelling) within 24-48 hours after installation.

If your insulation still smells by the third day (after installation), something is amiss. When the insulation smell subsists that long, the ventilation wasn’t executed properly.

Ideally, the installer should supplement natural ventilation with dedicated air exchange units in the insulation site. If this is not done, it is well within your rights to call the contractor and demand such units are installed.

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