3 Reasons Why You Should Not Use Packing Strap to Install Underfloor Insulation

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When insulating under your floor, choosing the right method to secure the insulation is crucial for its effectiveness and longevity. While packing straps might seem like a quick and easy solution, they are far from ideal. 


There are three compelling reasons to avoid using packing straps: they fail to provide sufficient support, they attract rodents by creating gaps, and they pose significant longevity and stability issues: 

  1. Insufficient Support:
    Packing straps do not provide adequate support to keep the insulation firmly against the floor joists. This can lead to sagging or falling insulation over time, reducing its effectiveness in maintaining thermal efficiency.
  2. Rodent Attraction:
    Incomplete or loosely held insulation can create gaps that are inviting to rodents and pests. These creatures can nest in the insulation, causing damage and reducing its insulating properties.  Polyester is unattractive to rats and mice as a source of food, but if you make it highly attractive to visit, they will! 
  3. Longevity and Stability Issues:
    Packing straps can deteriorate over time, especially in damp or fluctuating temperature conditions. This degradation can cause the insulation to fall out of place, requiring frequent maintenance and potentially leading to costly repairs. 

Understanding these drawbacks will help you make an informed decision and opt for more reliable methods, such as stapling or using specialised support systems like Joisties.

to ensure your insulation performs optimally and lasts for years to come.

Underfloor Insulation Failures:

If you need further convincing, here are some examples of what a ‘packing strap only’ securing method looks like. 

It starts off like this… 

To the untrained eye, this looks to be a reasonable installation – which is why householders get caught with an inferior result.  The insulation is “friction fitted” which is another way of saying “stuffed into the joist space” and help up with strapping that has been stapled maybe three times across an insulation batt.  Each batt is 1160mm long.  So three points of securing appears to be sufficient.  

But… over a small amount of time (less than 6 – 12 months), your underfloor insulation begins to look like this …

The batts have started to do what gravity wants them to do and start to give way from their friction fit space and the packing strap is insufficient to hold up all 1160mm of your insulation batt.  This may not be felt from the inside of your home as there is still a fair coverage of insulation.  However, the local rodent population now has your attention!!!  

Over more time, 12 months+ the insulation will push the staples holding the insulation in place.  The packing strap fails and the insulation sags away from your floorboards.  Your home is now feeling much cooler in winter, despite your attempts to heat it, the draughts are back and the rats are in a conga line to come and visit you! 

Underfloor Insulation Fixes:

 you are in this unfortunate situation, the good new is that this can be repaired, provided that you can access your underfloor area from underneath your home. 
This is very expensive, time-consuming and frustrating – but it can be done.  Please contact us for a referral to a company who may be able to provide that service in your area. 

The way to repair this is to staple the sides of the insulation into the joists every 100mm to 150mm along both sides of each insulation batt or roll.  

This video describes exactly how the insulation should have been installed in the first place. 

While packing straps might initially appear to be a convenient option for securing underfloor insulation, their inability to provide adequate support, tendency to attract rodents, and lack of long-term stability make them an impractical choice. 

If you are obtaining quotes from suppliers, the “packing strap” method will be much cheaper than a quote that installs your underfloor insulation using the staping method.  To quote a famous saying: Quality is remembered long after the price is forgotten. 

Instead, using the stapling method offers a much more reliable and effective solution. By securing the insulation every 100mm to 150mm with galvanised staples, you ensure it stays firmly in place, maintains its insulating properties, and provides long-lasting protection against thermal loss. This method not only enhances the overall energy efficiency of your home but also minimises maintenance and potential damage, offering peace of mind and comfort for years to come. For optimal results, always opt for proven, durable methods over quick fixes.

More Information

If you want to avoid disaster with your underfloor insulation, perhaps check out the most comprehensive give to underfloor insulation in Australia.  This guide has been written by ecoMaster who have installed more under floor insulation than any other company in Australia – 20,000 homes over 20+ years.   www.underfloorInsulationAustralia.com.au  


We have put our knowledge to work in the creation of a free masterclass on Underfloor Insulation.  You can register and watch the masterclass here