How We Accidentally Invented Polyester Underfloor Insulation (And Then Made It Better)

Cold Feet, Big Ideas!

Back in the early 2000s, underfloor insulation simply didn’t exist. Not in the way it does now. There were no kits, no how-to guides, and definitely no tradies offering it as a service.  No “Underfloor Insulation” section at Bunnings.

After retrofitting our own home (which had a very particular kind of underfloor structure), we became a little obsessed. We started sorting our friends into two camps: weatherboarders and brick veneer-ers.

Not for a dinner party. For science

DIY Science (with a Cool Room)

By then, we’d already spent six months building a heat chamber, hiring a cool room (as you do), and testing insulation products to figure out their actual thermal performance — not just what the packaging said.

Polyester was the clear winner.

So we armed ourselves with ceiling batts and crawled into a subfloor that felt more like a wombat warren. It was cold, cramped, and deeply unglamorous. We hauled in hundreds of batts, one at a time, and stapled them into place.

Was it awkward? Yes.
Was it exhausting? You bet.
Was it worth it? Absolutely.
But the process? It needed serious work.

A Sweaty Eureka Moment

A few months later, Maurice was elbow-deep in a Brunswick ceiling in the middle of summer. It was that dead zone between Christmas and New Year — when stock is scarce and the weather is cruel.

The only insulation available was fresh out of the ovens: not pre-cut batts, but long, continuous rolls.

From Prototype to Product

We went back to the manufacturer with a cheeky request:
“Could you make those rolls a bit wider? Wide enough to fit between floor joists?”

To our delight, they said yes.
And just like that, Australia’s first polyester underfloor insulation roll was born.

The Tinkering Never Stopped

From there, we refined everything.

✅ We upped the R-values — from R1.5 to R2.0, then R2.5
✅ We scrapped what didn’t work (farewell foil layers — you were expensive, fiddly, and kind of a pain)
✅ We made the rolls thicker, denser, and easier to install
✅ We built a system that actually stayed put once installed

The Vacuum-Pack Problem

But then came the battle over vacuum-packing.

As insulation got better (read: puffier), manufacturers wanted to vacuum pack it for shipping and storage. Great for freight. Terrible for performance — because insulation that is vacuum packed for a period of time (as yet unknown) does not bounce back.

We held firm for years, insisting on full-loft product. Eventually, the option disappeared. We were gutted. After all the years of collaboration, our flagship product was gone.

Not All Insulation is Created Equal

Since going DIY, we’ve tested insulation from all kinds of manufacturers — and we’ve seen it all.   Few things are more disheartening than pulling out a bag marked “R2.5” and finding something that looks more like … well not R2.5 . ????

The Value Poly Chapter

Back in 2019, we launched Value Poly.

By then, we had spent many, many years crawling around under timber floors, testing different insulation products, working out what stayed up, what slumped, what was people friendly to install, what deters rodents, what didn’t need to be replaced if it got wet, what makes it easy to inspect for termites and what made us quietly mutter under our breath.

Value Poly came out of all that.

We wanted a polyester underfloor insulation product that was good quality, practical, and more affordable. Not the cheapest roll we could get our hands on.  Not something we had to cross our fingers and hope would behave itself.  Just a solid, sensible product that did the job properly – and that we were happy to recommend.  And for several years, that is exactly what Value Poly was.

Then Came Polymax

In 2020, we also started working with CSR Bradford and added Polymax to our underfloor insulation range.  Polymax was a different product for a different part of the market.

It is a premium polyester underfloor insulation product, made by one of Australia’s best-known insulation manufacturers. It costs more, but there are good reasons for that. It is beautifully made, performs well, and has always been a product we were very comfortable putting into the range.

So, for a while, we had both.

Value Poly for people who wanted a good-quality polyester product at a more accessible price.

Polymax by CSR Bradford for people who wanted the premium option.

Both good products. Different roles.

Which, honestly, is how we like it. Houses are different. Budgets are different. Freight is different. The best product in Victoria is not always the most cost-effective product in Queensland, Tasmania, South Australia or Western Australia.

One-size-fits-all sounds tidy on a spreadsheet. It is not how houses work.

Then We Hit Pause

In 2024, we had a problem with Value Poly.

Not with the idea of Value Poly. We still loved the idea.

The problem was that our standard of quality and our manufacturer’s standard of quality had started drifting in different directions.  And that is not something we can shrug off.

Underfloor insulation is not a throwaway product. You do not want to crawl around under your house, wrestle insulation between joists and then later discover the product was not what it should have been.

Underfloor insulation needs to be consistent in manufacture. Once underfloor insulation is installed, it needs to stay up, it needs to keep its loft. It needs to keep doing its job.

So we paused Value Poly.

Could we have kept selling it?  Probably.

Would that have been easier?  Oh hell yes!

Would it have been the right thing to do?  Nope.

Polymax Kept Doing Its Thing

While Value Poly was on pause, Polymax by CSR Bradford stayed in our range.

Polymax is a premium product, and in many States it is still the product that makes the most sense. Sometimes that is because of availability. Sometimes it is because of freight. Sometimes it is simply because the customer wants the higher-end option.  It is a product we trust.  

Getting Value Poly Back

But we still wanted Value Poly back.

There is a real need for a good-quality, more affordable polyester underfloor insulation product. So we went looking for the right manufacturing partner.

And then came the usual ecoMaster process.  Samples arrived.  We tested them.  We installed them.  We consult with the manufacturers. More samples arrived.  We tested again.  We installed again.  We consulted again.

Then we waited for the right certifications to be issued – because, apparently, “we are really happy with it” is not a formal compliance category.   A shame, really.  But fair enough.

Value Poly Is Back

And now, finally, Value Poly is back.

It is once again doing the job we wanted it to do from the beginning: giving Australian households a good-quality polyester underfloor insulation option at a more accessible price.

It now sits alongside Polymax by CSR Bradford in our range, which is exactly where we want to be.

Two polyester underfloor insulation products.

Both carefully chosen.  Both products we are happy to recommend.

Value Poly is the practical, good-quality, more affordable option.

Polymax is the premium option from CSR Bradford.

The right choice depends on your home, your location, your budget, and what is practical to get delivered to you.  And if you are not sure which one makes the most sense, that is exactly what we are here for.

Still Improving, 23+ Years On

After more than 23 years in thermal efficiency, we still have not learned how to leave things alone.

We keep testing.  We keep asking annoying questions.  We keep checking what actually works in real Australian homes, not just what looks impressive on a spec sheet.  Because we are not just selling insulation.

We helped build the underfloor insulation category in Australia, and we still care deeply about getting it right.

Whether you choose Value Poly or Polymax by CSR Bradford, the goal is the same:

A warmer floor.  A more comfortable home.  Lower energy bills.

And one less reason to wear socks inside your ugg boots.

People Also Ask

⇒ Did underfloor insulation really not exist in the early 2000s?
Yes — it wasn’t something offered in a standard retrofit or by most tradies. There were ceiling batts and wall insulation, but nothing specifically designed for underfloor use, especially not in DIY roll format. We change that.

⇒ What makes polyester underfloor insulation better than other types?
Polyester is non-itchy, easy to handle, resistant to moisture and rodents, and maintains its shape over time. Unlike some other materials, it doesn’t sag or break down and is not impacted by a water spill, which means it continues to perform for years — no nasty surprises.

⇒ What’s the difference between compressed and vacuum-packed insulation?
Compressed insulation is gently squashed for shipping but regains its full loft after unpacking. Vacuum-packed insulation has been flattened with as much air removed as possible.  This is particularly problematic if it is vacuum packed when the rolls are still hot from the ovens.  Vacuum packed insulation often does not bounce back properly — which means it won’t insulate effectively – and certainly not to the R value that you have paid for.

⇒ Why is loft so important in insulation?
Loft is the thickness and fluffiness that traps air — and that trapped air is what slows down heat transfer. If insulation loses its loft, it loses its performance. That’s why we’ve always insisted on products that recover properly.

⇒ Can I install underfloor insulation myself?
Absolutely — if your home has enough clearance under the floor (ideally 400mm or more), it’s very doable as a DIY job. We have everything you need to help you do it right, with fewer swear words.

⇒ How do I know if my house needs underfloor insulation?
If you have timber floors and they are cold in winter, you have gaps in floorboards, or your heating never seems to keep up — there’s a good chance your home would benefit from underfloor insulation.