How Does Water Affect Insulation Materials

Insulation can become wet for a number of reasons, you may have a leak, a burst pipe, or it could simply be a build up of excessive moisture. You may be wondering what effects this has on insulation and its ability to function as it should. The simple answer is that water-damaged insulation should be treated as a serious issue and be investigated properly to ensure it doesn’t cause any long-lasting damage. 

Here, we take a look at the risks that wet insulation has, the causes of wet insulation, and how it can be prevented and treated. If you suspect your insulation has come into contact with water or excessive moisture, read on for more information!

The Risks of Wet Insulation 

Wet insulation is not only insufficient, it also presents a number of risks to your property. From the increased risk of mould growth to damage to the structures within your home or building, there are many things to consider when faced with water-damaged insulation. Here are some more potential risks of wet insulation: 

Insufficient insulation and loss of R-Value 

In simple terms, the R-value of insulation tells you how good the material is for protecting the space against cold air flow and retaining heat inside the property. The colder the climate in which you live, the higher the R-value you will need to ensure your insulation is sufficient for retaining heat. Whereas, if you live in a warmer climate, you will need a lower R-value. 

When your insulation gets wet, the insulation is not able to repel the heat back into the inside space, and instead, it conducts the energy. This means your insulation is less effective and will result in heat loss. The result? A colder house and higher energy bills.

Mould growth and damaged air quality 

Mould is a dangerous and toxic substance that can grow anywhere in your home. It thrives in damp and dark areas and once it starts growing, it can be really hard to get rid of it. The UK, in particular, is well known for mould due to the frequent wet and rainy weather we experience. Mould also presents health risks to those who live in close proximity to it. This includes coughing and wheezing, as well as bringing on asthma attacks.

There are factors that can actively encourage mould growth and this is a potential risk factor of wet insulation. Insulation is generally fitted in compact spaces with little room for moisture to escape and moisture that is trapped inside a small area will cause mould to start growing. 

Remember, if you do find mould growing in your home, it’s important to wear protective clothing when near it and cover the area until professional advice is sought.


Damaged walls and overall structural damage

If insulation is getting wet, it indicates that there is an excessive amount of water in the area of your home or property. If left untreated, the water will begin to degrade your walls and surrounding infrastructure. To add to this, wet insulation dramatically increases the weight of your structures. This is particularly dangerous for roof insulation because if it is too heavy it can eventually collapse inwards. This can quickly turn into an expensive and dangerous job as it will need repairs from a professional.  

The signs of water damaged or wet insulation 

Since the insulation in your property is beneath the finishing wall surface, it can be difficult to realise that your insulation is damaged by water. However, there are a few things you can look out for below. If you have any of the following signs in your home, it might be best to further inspect by taking a look at the state of your insulation. The signs to look out for include: 

  • Damp, musty smells 
  • Visible mould growing on walls 
  • Any brown staining on walls
  • Damaged wallpaper such as bubbling and peeling 
  • Dips in the ceiling, walls, or floor 

What To Do If Insulation Gets Wet

How you treat and respond to wet insulation depends entirely on how wet the insulation gets. For example, if it is only slightly damp then it may be an option to dry the insulation out. You can do this by using a dehumidifier in the area. Wet insulation that is thoroughly drenched and in a closed wall cavity likely won’t dry out and in this case, it’s better to completely replace the damaged insulation. 

Let's take a further look at how different types of insulation respond to getting waterlogged

Fiberglass insulation - Fiberglass insulation is waterproof, however, this doesn’t mean it's designed to get excessively wet when in use. When fiberglass insulation gets wet, the water displaces the air gaps that are present between the fine glass fibers which greatly reduces its ability to insulate the property.

Cellulose insulation - Cellulose is a loose-fill product. The material is designed to fill the space and not become compressed. When the fibers become wet to an excessive level, their weight increases, and the material will gradually compress and become dense. The more wet the cellulose insulation becomes, the less space it will fill, and it will eventually become insufficient as an insulator. 

Insulated plasterboard - If insulated plasterboard is exposed to high levels of moisture over an extended period of time, it will prevent the plasterboard from carrying out its purpose. Plasterboard is designed to absorb a high amount of moisture, however excessive amounts can lead to sagging, bulging and discolouration. If your plasterboard reaches this stage, it’s more efficient to completely replace it.

Replacing your insulation due to damage 

If your insulation is drenched or shows signs of other damage like mould growth, then replacement is essential. It might seem like an inconvenience at first, but replacement is reasonably priced and it will be healthier for your property in the long run, reducing the risks of further damage caused. Insulating a property usually costs around £20 per m², which is much cheaper than replacing walls or other structural components further down the line.

Keeping Your Insulation Dry By Preventing Moisture Damage and Leaks  

People are often not told that moisture build up can cause your insulation to get wet. This is because warm air holds a lot of moisture, and it has to go somewhere. Therefore, it ends up building up on the insulation layer. A good way to prevent moisture in the air is by investing in extractor fans and dehumidifiers in your property, that way condensation won’t build up as quickly. 

You can also check your property for stronger leaks or burst pipes that are letting water in. If you suspect there is a leak in your roof and loft area, for example, you can go up there on a rainy day with a torch and search for any puddles, dripping water, or traces of water. Remember, simply fixing the leak isn’t enough, and a proper inspection of all areas, including the insulation, will be needed. 

It’s also a good idea to prevent wet insulation by using the best products for wet areas in your home. Areas like the bathroom and kitchen are prone to moisture build up and condensation. This means it is beneficial to use tile backing boards to prevent moisture damage.

Need Help Preventing Water-damaged Insulation?

We hope you now have a better understanding of the effects and risks of water-damaged insulation. If caught early, water-damaged insulation shouldn’t cause too many problems in your property. If you have any questions about what to do if your insulation is damaged, please do not hesitate to contact us and we will be happy to help you.

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