• Can Insulation Get Wet? An Expert Guide

    | by Dave Ashbolt

    It’s a known fact that insulation is a key element in any construction project. But what happens when insulation gets wet? Can it still be effective?

    In this expert guide, we’ll take a look at the different types of insulation and how they react to moisture. We’ll also provide some useful tips on what to do if your insulation does get wet. By the end of this guide, you’ll know everything there is to know about insulating your construction projects against moisture. Let’s get started!

    Wet Insulation – Prevention Is Better Than Cure

    Wet insulation is a serious issue that can cause a wide range of problems in your home if not taken care of right away. By taking steps such as sealing up any potential entry points for excess moisture and using products designed specifically for damp conditions you can reduce the risk of moisture infiltrating existing or newly installed insulation and ensure maximum energy efficiency throughout all seasons!

    Taking these measures will not only save you money on energy bills but also provide peace of mind knowing that your home is safe from any potentially hazardous situations caused by wet insulation.

    The Impact of Wet Insulation

    When insulation gets wet, it will no longer be able to perform its job correctly- and this can have serious consequences for both you and your property. This is especially the case with materials such as wood fiber insulation. Wood is highly susceptible to moisture saturation and warping – both of which threaten to compromise surrounding structures.

    Similarly, loose fill insulation (such as fiberglass insulation and cellulose insulation) is another material that temporarily loses its thermal resistance in the presence of moisture. Should fibreglass absorb water, the water droplets will infiltrate the air spaces between the fine glass fibers, greatly reducing the material’s insulant properties.

    If you don’t replace or dry out wet insulation quickly enough, you run the risk of mould growth in the area where the dampness has occurred. Not only is mould unsightly and smelly, but it can also trigger allergic reactions in some people who are sensitive to mould spores. Additionally, mould can also cause structural damage over time if left untreated due to its ability to eat away at organic materials like wood.

    On top of this, water-damaged insulation tends to become less effective at regulating temperature within the home as well. This means that even if you manage to dry out the affected area quickly enough before any structural damage occurs or mould starts growing, you may still find yourself with higher energy bills because your house has become less efficient at regulating temperature than before the incident occurred.

    What Can Cause Insulation To Retain Moisture?

    Everyday activities like showering and cooking generate steam and warm air that could potentially get trapped within an unventilated building.

    Should humidity linger in a property that lacks an adequate ventilation system, the moisture then gets trapped in the insulation itself. This can result in building materials such as plaster absorbing the moisture from the surrounding insulation materials, making for an infestation of damp. This could lead to problems with mould or mildew growth.

    In terms of applications, roof leaks are one of the leading causes of wet insulation. While not immediately obvious, a roof leak can cause a great deal of damage to your attic insulation before you discover it. For this reason, it is crucial that you select adequate mold-resistant roof insulation to thoroughly protect your property’s thermal envelope.

    What To Do If Insulation Gets Wet?

    If you are worried about moisture already existing in your walls or attic space prior to the installation of new insulation, there are products such as spray foam that can be used to seal off any areas where water could be getting in. These products should be applied by experienced professionals who have experience dealing with moisture issues in homes.

    If the area has already been damaged by water leakage then replacing any affected materials may be necessary before new insulation can be installed correctly without the risk of further damage occurring down the line.

    When dealing with wet insulation in a closed wall cavity, we advise that you remove the wet cavity wall insulation and allow the cavity to fully dry out before attempting the installation of new materials.

    How To Prevent Insulation From Getting Wet?

    The best way to prevent wet insulation is to ensure that your home is properly sealed and insulated against moisture before installing new insulation. This includes checking for holes, gaps, and cracks around windows, doors, vents, and pipes. Sealing these points with caulk or weather-stripping materials will help keep out any excess moisture from entering your home’s walls and attic spaces.

    On top of creating an air tight seal, ensuring that any vents or exhaust fans are properly installed so that they don’t draw moist air into the space will help as well.

    There are a few steps you can take to prevent your insulation from getting wet:

    – Make sure your roof and gutters are in good condition and are properly draining

    – Keep your home well ventilated, especially in the attic

    – Add technical insulation around pipes and other objects that could cause water damage

    – Use a water repellent insulation, like spray foam or closed-cell foam insulation

    – Cover your insulation with a moisture barrier, like plastic sheeting

    What Insulation is Waterproof/Water Repellent?

    In order to keep your home as watertight as possible, you’ll need to make sure you have the right insulation in place. But what type of insulation is actually waterproof or water-repellent? Let’s take a look.

    • Rockwool insulation is water-repellent due to the resin bond it’s covered in. Rockwool insulation is moisture resistant and vapour permeable. Engineered to repel water, water will drain away rather than soak into the insulation, while gaseous water vapour will simply pass through it. Therefore, if Rockwool gets wet, you can dry the material out and it will maintain its original performance characteristics. Rockwool manufactures a range of acoustic insulation slabs, such as RWA45 and Flexi Slabs.
    • Insulation boards tend to have good moisture resistant and water repellent qualities. Products such as Celotex and EcoTherm boards for instance have aluminium foil facings on both sides, and a PIR foam that is resistant to water.

    It’s worth noting that these types of insulation can get wet if the insulation gets damaged, so it’s always worth checking the condition of your insulation regularly.

    If you’re looking for insulation that is resistant to water damage, then spray foam or closed-cell foam insulation are the best options. They will keep your home well insulated and dry, no matter what the weather throws at them.


    There’s no denying that wet insulation is bad news for homeowners everywhere. It increases energy costs by making homes less efficient at regulating temperatures and creates an environment where mould growth is more likely to occur—which can potentially cause health problems for those living inside the home as well as long-term structural damage in some cases.

    Therefore, it’s important that homeowners take steps to ensure their insulation stays dry in order to protect their properties and avoid costly repairs down the line. If your home’s insulation ever gets wet, make sure you take action right away!

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