Wet Insulation: Everything You Need to Know

While facing a storm or other severe weather conditions can be devastating on its own, the situation can get overwhelming with the aftereffects that you might have to deal with. Let’s face it, it is not just about such adverse weather conditions; even if you happen to live in a humid and rainy region, or there arises a water damage in your building’s plumbing, one of the few major problems you will have to deal with is wet insulation.

wet insulation

How does insulation get wet

Some of the major causes of wet insulation are as follows:


A crucial step involved in the process of insulating your home is installing vapor barriers over the face of the insulation, which is basically the side of the wall that faces the room. If this step is overseen, the moisture condensation on the wall can easily penetrate the insulation, causing it to form a blob, followed by air pockets. As a result, you will be left with wet insulation that can lead to various issues and damages.

Plumbing Leaks

Something as small as a pinhole developed in your water pipes can lead to wet insulation by spraying sufficient water. Of course, this water will start soaking into the drywall; moreover, if your pipes are left uninsulated, cold water passing through them can cause condensation, which in turn can enter the insulation layer in your walls. Other types of plumbing leaks, like leaking toilet, can also cause water to drip into your structure’s insulation.

Overhead Drips

In addition to the causes discussed above, moisture/water dripping from up above is another common cause of wet insulation. In most cases, this happens if the ventilation in your attic is poor. As poor ventilation can suppress air circulation, condensation of moisture happens, which then penetrates through your floorboards, reach the wall cavities, and the dripping starts.

Additionally, wet insulation can also be caused by:

  • Invasion of air from doors, windows, siding gaps, etc.
  • Ground moisture, which can make the insulation in your crawl space and/or basement wet.
  • Snow.
  • Heavy rains, storm, and other wet weather conditions.

Problems Caused by Wet Insulation

Wet insulation can become a cause for a lot of structural issues:

Structural Instability

Wet insulation can have an adverse effect on the entire structure of your building. Trapped in moisture can penetrate through the ceiling, walls, and other areas, thereby cracking and rotting the surfaces, and eventually collapsing the whole structure.

Reduced Energy Efficiency

Were you promised that your roofing system will bring in significant energy efficiency benefits? While that is true, with wet insulation, you cannot expect to reap those benefits. This is because of the basic fact that water conducts energy, which means your wet insulation will also conduct energy rather than resist it. As a result, you will encounter higher heating and cooling bills, rather than conserving energy.

Nulled Warranty

If you happen to live in an older home and thinking about retrofitting a new roofing system, you need to work towards eliminating the moisture already present under your structure before proceeding forward. This is because the existing moisture can easily and quickly penetrate through your new roofing system, and deteriorate the same in no time, thereby causing premature damage to parts of or the entire structure. And when this happens, the warranty of your new roof will not cover such damages.

Health Issues

As you would be aware, indoor air quality in your property is extremely important for you and your family to remain healthy. When you have wet insulation, moisture from it can lead to the growth of mold and bacteria, which can make the very air you breathe unhealthily. And the longer you leave the problem unattended, the more serious the health issues will be.

Effect of water on different types of insulation

Water/moisture affects different types of insulation in different ways. Here is all the information you need to know about the same:

Spray Foam Insulation

If you find hard white foam in your wall and floor cavities, then your home is insulated with spray foam insulation. Fortunately, with this type of insulation, you don’t have to worry about having to completely replace your building’s insulation. This is because spray foam will dry out over time. The length of time it will take for the foam to dry out depends on how wet it is and the level of ventilation around it.

However, do keep in mind that leaving your spray foam insulation wet for an extended period of time without proper airflow or ventilation to dry can become problematic in different ways.

Fiberglass Insulation

If you find loose-fill insulation or pink/yellow/green batts in your wall and floor cavities, your home is equipped with fiberglass insulation. This type of insulation is typically made from recycled glass and water, as a result of which it is more water-resistant than other insulation materials. However, when it does get wet, its insulation ability reduces significantly.

In this case, you can dry the insulation by placing a fan or dehumidifier near the affected area. You can also try to remove the wet batts and place them in a warm area to dry, and install them back in their place after.

Cellulose Insulation

If your wall and floor cavities are filled with loose, grey fibers, then the insulation type used in your home is cellulose. Known to be an environment-friendly solution, cellulose is made mostly from recycled paper, which makes it obvious that restoring your insulation once it gets wet can be extremely difficult.

In the case of cellulose insulation, if the area that has gotten wet is quite small, you might be able to remove it and leave it to dry in a warm place for a couple of days. But, if the damage is beyond repair, with an extensive area damaged, you might have to completely remove the insulation and have it replaced.

How to identify wet insulation

Before things get worse, you can easily read the signs of wetness in your home:

  • Dark wall marks – If you notice darks marks on your walls, it is a clear sign that you could have damp or wet spots around your home. Usually caused by the moisture content in the wall, this is one easy way to find out relatively early what you are dealing with.
  • Moldy smell – If you have wet insulation issues in your home, you are most likely to notice a moldy smell whenever you open the affected room.
  • Cold walls – Wondering why your walls have been cold to the touch lately? It could be because of wet insulation in your walls.
  • Peeling wallpaper – If certain areas or rooms around your home have wallpaper peeling off of them, it could be an indication of the presence of moisture inside those walls.

Insulation Testing

Yes, you can test your insulation, using an infrared thermometer. This simple and less expensive device does an excellent job of checking the performance of your insulation without the need to remove any drywall. All you have to do is check the temperature of the area where you doubt the insulation is wet and compare it with the temperature from other dry areas of your wall. If you notice a serious difference in the two temperatures, it could be an indication that the insulation is lacking in performance, and you should have it checked to know if it can be repaired or needs to be replaced.

Preventing Wet Insulation

Preventing your property’s insulation from getting damp or wet would be the best and wise way to not deal with the potential issues. Here are a few tips:

Check for leaks

This is a no-brainer. Leaks in the roof will obviously get your attic insulation wet. In addition, this water can also leak into the insulation between the walls through the attic. It is easier to replace your attic insulation but replacing your wall insulation is going to cost you more time and money. So if you see any signs of dampness anywhere in your house, check for leaks before your insulation gets wet.

Provide proper ventilation

Proper ventilation is essential to prevent condensation inside your home, which can happen from everyday activities like bathing and cooking. The easiest way to ventilate your home is by leaving your windows open for a minimum of about 20 minutes every day. If you notice that a particular room has poor ventilation or is highly prone to condensation, like a laundry room, you can have a trickle vent installed, which you can keep open at all times. Also, make sure your attic has enough ventilation, you can install an attic fan or additional roof vents if needed.

Heating and Dehumidifying

During the winter months, try keeping your home at a consistently warm temperature to prevent the surfaces from getting too cold to allow condensation.

Purchasing a dehumidifier would be a great investment, as it helps lower humidity levels inside your home, while also keeping it warm. This process, in turn, helps prevent condensation and thereby wet insulation.

Wet insulation can be a serious threat, not just for the structural integrity or aesthetics of your property, but mainly for the health of your loved ones and yourself. Therefore, preventing its occurrence right off the bat would be the best way to go about it. Check periodically for damp areas around your home and have a professional assess your property for the same to stay safe and worry-free.

Charles John

Experienced HVAC technician with 8 years of experience in the industry. Capable of handling all sorts of heating and cooling equipment as well as proficient in operational management, construction-related techniques such as preventative maintenance, electrical troubleshooting and AutoCAD

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