Under Floor Insulation Installation

In this video we show you how to install Earthwool® glasswool insulation correctly under the floors of your home. Please also find a text summary of the steps involved along with a link to important safety docs below. 

How to install Earthwool glasswool: Underfloor Insulation Segments:


EarthwooI glasswool insulation is a highly cost effective way to improve the thermal efficiency in homes and in commercial buildings. Maintaining desired room temperature for comfortable living and working environments, EarthwooI glasswool insulation is a proven energy saver.


Assess the underfloor condition and structure together with the method of installation you are to use based on the appropriate requirements established in the building code, site assessment and or plans provided. Installation must be completed to the requirements of relevant standard: AS 3999:1992 or NZS 4246:2006.



Tools required to install Earthwool Glasswool Insulation Underfloor Segments:


  • Tape measure
  • Lightweight overalls
  • Electrical hazard labels
  • Headlamp/general lighting
  • Protective clothing
  • Safety glasses
  • Polythene banding, minimum 12mm wide and 50kg breaking strain
  • Staple Gun/tacker to fix minimum 8mm staples
  • Galvanised/Stainless staples (minimum 8mm)


Step 1


  • Ensure the mains power is ‘Off’ and do a pre-work inspection of the installation area.
  • Check the joist width to determine the correct insulation segment width (e.g.480mm or 610mm) – Earthwool glasswool: Underfloor segments are designed to fit full width or to have a fold down one side.
  • Earthwool glasswool: Underfloor segments should always be fitted with strapping – see video for more.
  • If product is fitted with fold, the fold should be no more than 75mm below bottom of product.
  • Earthwool glasswool: Underfloor segment insulation is easily cut with a sharp knife.
  • When installing, give each segment a light shake and gently bounce it on its side to ensure the product expands to the full thickness.


Step 2


  • Place long edge side of the underfloor segment neatly into the joist/underside of the floor intersection.
  • Push the underfloor segment flush up under the floor – fold the opposite edge down so that a friction fit is achieved.
  • Make sure to leave no gaps between the insulation and the framing and the underside of the floor.
  • Fix strapping across the underside of the underfloor segment (each segment is to have a minimum of 3 runs of strapping applied – see diagram:

Underfloor Insulation Install OR Underfloor Insulation Install

  • Strapping can be fixed using staples (non-conductive), ensuring they maintain the band appropriately by giving it a light tug (double staple if required) – see diagram:

Under Floor Insulation Installation 2

Step 3:

Always make sure joins have good friction fits, with a uniform placement of insulation flush to the underside of the floor, and strapping applied flush to the underside of the insulation.

Step 4:

Once installation has been completed fix the Earthwool glasswool: Underfloor segments outer wrapper label where it can be easily see from the entrance access-way for customer verification (and retained for certification).

For further detailed instructions and safety and precautions click here to download the pdfDon't forget to also check out our DIY Safety Instructions and Precautions before you start.

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