How to Control Condensation Using Wall Insulation?

How to Control Condensation Using Wall Insulation? - Blog image

Firstly, condensation forms when humid air meets a cold surface and that contact creates water droplets. The use of exterior wall insulation can warm sensitive surfaces and work to reduce the risk of condensation build-up. Additionally, choosing the right wall wrap can reduce the risk of condensation and mould growth. By installing an airtight membrane such as a wall wrap, this can increase the performance of wall insulation by up to 20%. So, essentially airtight homes are more energy efficient but adequate mechanical ventilation is required to control moisture.

Does wall insulation cause condensation?

It depends, in a well ventilated building condensation should quickly evaporate. However, in a building that is airtight and not properly ventilated, condensation build up can occur in vulnerable areas such as; carpet, wallpaper, timber floors etc. You may even notice a damp ‘muggy’ smell in your home, and small black spots appearing in areas such as the bathroom, basement or attic. This is when you have a problem that should be quickly addressed and resolved. Before installing any type of insulation, especially wall insulation, we recommend inspecting the cavity spacing to ensure there is adequate ventilation.

On the other hand, don’t be afraid to install bulk wall insulation if you have good ventilation in your home, the benefits of installing wall insulation are huge and worthwhile! You can significantly reduce summer heat gains and winter heat losses by up to 25% with wall insulation and wall wraps that make your home airtight.

insulation cause condensation

What causes condensation?

Water vapour is naturally produced in everyday activities such as cooking, washing, and using heating appliances. Once vapour levels in the air reach ‘saturation point’, moisture in the air turns into water droplets and condensation forms.  When this occurs, the air is said to have a relative humidity level of 100%. Usually humidity levels in a home remain at around 50-70% relative humidity. As mentioned above, problems occur when there is not enough ventilation for condensation to evaporate. The greatest concern to homeowners and builders is the formation of excessive levels of interstitial condensation, which can cause irreversible damage to the structure of a building. Interstitial condensation forms on the interior side of a building structure such as; walls, flooring or roof space.

Factors that contribute to condensation

  • The temperature and relative humidity of air, as well as the air pressure of inside and outside the building.
  • The composition of the wall itself, including the type of floor, wall and ceiling.
  • Type of wall surfaces, such as; cladding, paint type and internal linings.

How to minimize condensation in your home?

To minimize and potentially eliminate the risk of condensation build-up in your home, we recommend making sure all ducts are vented to the outside of your home and ensure nothing is blocking the flow of ventilation.

Make sure you choose insulation that fits your wall cavity and ensure you don’t completely fill the cavity space as this will allow air flow through this free space and keep the walls separated and dry. Filling the entire wall cavity with insulation means that air flow is restricted and hence any condensation that forms will take longer to evaporate.

How to treat condensation in your home?

Control humidity levels in your home by installing extractor fans into areas of your home which have excessive amounts of moisture such as the in the bathroom and kitchen.

Install insulation into your wall cavity to keep temperatures at a level above dew point. Just ensure that the insulation you are adding is the appropriate size for your cavity wall.

Check your Building Code of Australia (BCA) compliance report. It specifies the R-value requirements for different parts of your home as well as requirements for ventilation systems. According to BCA requirements its recommended installing a minimum wall insulation R-value of R2.5.

Tips for Installing Insulation - DIY Home Insulation

DIY Ventilation to minimise condensation

Installing exhaust fans in your building it a great DIY solution to reducing moisture and condensation. The bathroom and kitchen rooms will benefit the most from an exhaust fan to get rid of steam and condensation. Remember that when you are cooking, always turn on extractor fans, to get rid of excessive moisture and leave the extractor fan on for a few minutes are cooking before turning it off.  The bathroom is another room in the house where there will be excessive moisture, so ensure the exhaust fan is on and bathroom windows opened. Keep the bathroom door closed to keep moisture from escaping into other parts of your home.  

Ventilation to minimise condensation

Should I use Vapour Permeable Wrap or Wall Insulation?

Essentially, you can use both vapour wall wraps and bulk wall insulation together. Vapour membrane products prevent the entry of liquid water and reduces air flow through the membrane thus reducing the transfer of moisture. Installing a vapour wrap can greatly reduce the risk of mould growth issues in climates especially prone to these issues. This product is suitable for installation behind both brick veneer and lightweight clad walls.  

When using vapour permeable wrap and wall insulation together, ensure you maintain an air space of at least 25mm between the insulation batt and the reflective side of the vapour wrap. It is important to choose the right insulation for your climate, and construction type. Just remember, the higher the R-value the greater the thermal performance and insulation ability.

What’s the conclusion?

Wall insulation doesn’t cause condensation, but it needs to be installed correctly with adequate ventilation to minimize condensation formation and mould growth as a result. We recommend using a vapour permeable wrap and bulk wall insulation together to achieve the highest thermal rating and moisture control. If you are unsure about products or installation processes, please Contact Us for more information.

5 thoughts on “How to Control Condensation Using Wall Insulation?

  1. Jason Gray says:

    Trying to prevent condensation on the bottom of a box gutter in the interior of building under construction. Very limited space to insulate under side of box gutter between trusses & supports.
    Job location North Queensland 4884

  2. Adam says:

    Hi guys. If I was to remove the internal plasterboard to retrofit wall insulation is it still possible to use a vapour membrane or can this only be installed from the exterior side? It’s an old weatherboard home in regional Victoria, but the internal plaster is tired and worn out so thought I could kill two birds with one stone but don’t want to introduce a condensation issue in the process.

    • Pricewise Insulation says:

      Hi Adam,

      Thanks for your question. You can install permeable wall wrap from the inside the dwelling once the plaster has been removed. It’s simply a matter of cutting the permeable wall wrap to size and stapling it between each joist.

      Feel free to contact us on 1300 729 639 or via email at if you have any further questions.


  3. Edward says:

    My house is fully insulated and still getting condensation on my ceiling on a outside wall above window I’m thinking not enough soffit ventilation attic is hot in the summer and very cold in the winter

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