Does Underfloor Insulation Cause Dampness?

Does underfloor insulation cause dampness?

Installing premium underfloor insulation in your home can reduce energy usage by 10% to 20%! Home insulation is a great investment which can pay itself back in around 3 to 5 years. Regardless of if you have insulation or not, your home can be prone to dampness and mould growth if there is inadequate ventilation and excessive moisture. That’s why it’s important to address these issues before you install your insulation. In an existing home with insulation, it is important to check your underfloor insulation for any damage or moisture retention. If problems do exist, we recommend either removing the insulation yourself, or getting a professional to assist.

Can insulation cause condensation?

Underfloor insulation does not cause condensation. However, if you are installing insulation into your underfloor area you must have adequate ventilation. Without appropriate ventilation the air becomes stagnant and moisture trapped, which can lead to dampness and mould growth. Planning ventilation in your underfloor area is important and can be as simple as installing small vents on the surrounding walls of your basement area. This promotes air movement through your underfloor area and can also minimize the risk of mould growth. Ensuring adequate ventilation in your entire home is also important and we recommend talking to your builder if you are planning to install a whole-building ventilation system.

Things to take care while insulating underfloor

Firstly, it is important to decide which insulation is best for you and your home. Regarding R-value and thermal performance, we recommend installing a minimum of R2.0. Make sure you measure the area to be insulated and calculate the square meters m2, do this by multiplying the length of the area by the width. Floor insulation is available in either 415mm or 565mm widths, measure the width between your floor studs to determine which size you need. Choosing what type of underfloor insulation is also important, for example rolls or batts. Insulation rolls are easier to install however insulation batts are easier to move especially is small tight spaces. Lastly, decide whether you want to install the insulation yourself or have a professional do it for you. Remember to watch our DIY instructional videos for more information.

DIY Underfloor Insulation Project – Tools and Materials

  • Gloves
  • Scissors
  • Staple Gun
  • Tape measure
  • Knife
  • Floor insulation strapping
  • Underfloor insulation batts or rolls


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