Old batts up there? · find out what they’re really worth
Why aren’t my old batts working? Measure them and you’ll see.
Put a ruler in it. Depth is what insulates, so the thickness you measure plus the material tells you what your ceiling is really doing. Find your depth in the table below and read across.
I’m Peter Johnson. This is the page I wish people had before they rang me, because the R-value printed on a twenty-year-old batt is almost never what that ceiling is delivering today. Measure it, read it off, and you’ll know where you stand.
Comfort Zone insulation.team
Family-owned insulation manufacturer, making comfy homes since 1986
Exposed-beam tile roof
insulated properly with Cellulose Fibre Insulation
Real reviews, real jobs
What our customers say
Genuine Google & hipages reviews from Comfort Zone customers across SE Queensland.
- A
Angela M.
SE Queensland
“The fact that I can't even tell it's 6 degrees outside when I wake up in the morning speaks for itself. Have wasted so much money attempting to heat and cool an uninsulated home. Worth every $.”
- Phipages
P Peter
Alstonvale, 2024
“Connected with Comfort Zone Insulation and would recommend them”
- J
Jessa B.
Brisbane
“It dropped about 4 degrees straight away, and we added another 3 with the second job. I appreciate Peter's honesty, and the team showed pictures before and after.”
- Nhipages
Nola M
Birtinya, 2024
“They were courteous and competent.”
- I
Iain V-B.
Brisbane
“Quick and polite service. Great follow-up advice and photos sent for our records. Above and beyond what we expected. Would highly recommend.”
- Jhipages
Jennifer's E
Upper Caboolture, 2024
“Excellent customer service. Highly recommended. Has a profound knowledge of insulation products and has the best interest of his customer.”
- G
Gerry S
Fitzgibbon, 2023
“I used Comfort Zone and they have a done an excellent job.”
- Jhipages
Jennifer
Upper Caboolture, 2024
“Excellent customer service. Highly recommend. Has a profound knowledge of insulation products and has the customer best interest.”
- J
Jung K
Riverhills, 2023
“An experienced family operation. Highly recommend. Thank you for the great job!”
- Dhipages
Diane A
Ormeau, 2024
“Peter and crew did a great job I would definitely recommend them”
- D
David H
Sunshine Coast, 2021
“Completed the job as quoted and to a high standard. Great personal service. Would highly recommend Comfort Zone for ceiling installation work.”
- Thipages
Timea
Highland Park, 2023
“I was extremely satisfied with the service they provided. They gave a very thourough explanation of the materials used, the way the work will be carried out and the price I had to pay was the exact amount quoted, no hidden costs included. They arrived on time, well prepared and workwas carried out exactly how they said it would be, they were super efficient, well prepared and were kind enough to even clean up after themselves. The services they provided was second to none! I don't hesitate to recommend them for any insulation job!”
- B
Benjamin H
Carseldine, 2019
“Very good explanation about their works. Advice of existing problems with the roof. Clean work. Very professional.”
- Mhipages
Mark
Pottsville, 2017
“Michelle, we are done - Peter from comfort zone insulation was very helpful. very honest with his recommendations - in fact he told me that the product my daughter had if installed correctly was superb. Thanks Peter you are a champion and i would recommend you to any person that was wanting professional advice and old school service.”
- I
Ian G
Burnside, 2019
“Good information, communication and professionalism.”
- Jhipages
Jessica
Pottsville, 2016
“This business offers a fantastic product that other businesses did not. Pump in ceiling insulation. Knowledge of the industry second to none.”
- D
Danny D
Boondall, 2018
“He explained everything he was going to do and the different types of insulation they used. He talked through the different options but made a recommendation for the one most people use, which is the one I chose. He was very understanding towards what I needed and not about himself.”
- Jhipages
Jack
Pottsville, 2023
“Excellent communication and informative. Professional.”
- G
Graham R
Riverhills, 2018
“Comfort Zone. Turned up ahead of time, completed in about 2 hours, cleaned up. All good. Very motivated installation team.”
- Thipages
Tony P
Redland Bay, 2023
“Very knowledgeable about insulation”
- A
Alex B
West Ipswich, 2018
“Fast, friendly, efficient.”
- Shipages
Steve
Redland Bay, 2017
“Excellent job and reasonable price.”
- L
Luke D
Mcdowall, 2017
“Peter did a good job. It was a quick and clean service. I'm happy to recommend!”
- Bhipages
Bruce H
Kuluin, 2023
“Prompt and efficient quoting.”
- B
Brendon
Brays Creek, 2016
“Peter supplied and installed roof insulation for me. He was very informative and provided good advice.”
- Ghipages
Gerry S
Fitzgibbon, 2023
“I used Comfort Zone and they have a done an excellent job.”
- T
Trevor G
Brookside Centre, 2016
“Excellent tradesmen from Comfort Zone Insulation. They were punctual and cleaned up after. Highly recommended.”
- Thipages
Tamara
Underwood, 2023
“Peter is honest, hard-working and came on time. Knew excally what he was talking about and answered my questions. Would 100% recommend”
- J
John G
Beaudesert, 2019
“Peter is an honest person who provided me with the information I wanted then performed a good job with great results for the benefit of myself and my family.”
- Shipages
Sterling G
Ashgrove, 2023
“Comfort Zone were very knowledge with great communication and follow up”
- Ghipages
Graham R
Riverhills, 2018
“Comfort Zone. Turned up ahead of time completed in +- 2 hours cleaned. All good. Very motivated installation team”
- Jhipages
Jung K
Riverhills, 2023
“An experienced family operation. Highly recommend. Thank you for the great job!”
- Khipages
Kathy A
North Lakes, 2023
“We connected with Peter through HiPages and he was prompt, professional and even came back after the job was complete to assist with a question we had. We would highly recommend Peter for further insulation works.”
- Dhipages
David H
Sunshine Coast, 2021
“Completed the job as quoted and to a high standard. Great personal service. Would highly recommend Comfort Zone for ceiling installationn work.”
- Shipages
Sue H
Sunshine Coast, 2021
“Incredible customer service”
- Ehipages
Eileen C
Cedar Vale, 2021
“Quality work, good customer service, prompt”
- Chipages
Craig M
Woody Point, 2021
“Called within 5 minutes of request. Very knowledgeable and explained job in great detail, provide great advice in prior preparation for works required. Very friendly and helpful.”
- Jhipages
Jenny C
Plainland, 2021
“Although I did not hire Peter I was impressed with the initial contact and the knowledge he was willing to impart. I was treated with respect which I appreciated. I would have hired but I received a lower quote.”
- Qhipages
Quinton
Coomera, 2020
“Professional installation without any short cuts. True to their word with high integrity. Response from Comfort Zone Insulation”
- Ghipages
Gary P
West Kempsey, 2020
“Came & Gave a free quote”
Before you climb up there
Loose grey fill in an older roof: cellulose or asbestos?
If you’ve never seen either product, they can look similar enough from a manhole that you shouldn’t go poking at it. Loose-fill asbestos was pumped into some ceilings decades ago, and if your home predates about 1980 and there’s a fill up there nobody can account for, leave it alone and have it identified properly. That part is a genuine warning and I mean it.
What I won’t do is pretend it’s a hard call for someone who knows the products. It isn’t. Anyone who has handled both tells them apart instantly, on sight and on feel. Cellulose is soft grey shredded paper; you can see the paper in it. Loose-fill asbestos is a harsh mineral fibre and behaves nothing like it.
I say that because I keep hearing about builders and pest-control blokes putting their head through a manhole, seeing cellulose, and telling the owner “could be asbestos, could be cellulose, I couldn’t say”. That isn’t caution, it’s not knowing the product. It frightens people out of good insulation and it’s cost customers of mine a lot of worry over nothing. If someone in a trade tells you that, get a second look from someone who installs the stuff.
The three you’ll find in a Queensland ceiling, photographed in real roofs. At the same depth they are not worth the same number.
Two minutes at the manhole
How to measure your ceiling insulation depth.
A ruler and a torch gets you a better answer than any label on a bag.
1
Measure from the ceiling, not the joist
Push the ruler down through the insulation until it touches the ceiling surface. The number that matters is total depth above the plasterboard.
2
Take three or four readings
Near the manhole, out towards the eaves, and somewhere in the middle. Insulation is never even, and the thin spots are what cost you.
3
Note whether the joists are covered
If you can see the tops of the joists standing proud like stripes, that tells you as much as the ruler does.
4
Look for the bare patches
Open seams, missing sections, big clearances around fittings. Come back to the gaps section below, because they cost you more than depth does.
Don’t fancy the trip? Take a photo from the manhole. Get a tape or a ruler in the shot and send it through. I’ve been in enough roofs to tell you what you’re looking at, and it costs you nothing.
Step two
Cellulose, glasswool, rockwool or polyester: which is in your roof?
You need the material as well as the depth, because the same thickness gives a very different number depending what it's made of.
Comfort Zone insulation.team
Family-owned insulation manufacturer, making comfy homes since 1986
Blown-in cellulose
Loose grey fibre with visible shredded paper in it, laid as one continuous blanket with no joins. Soft, and it follows the shape of everything it's poured over.
Comfort Zone insulation.team
Family-owned insulation manufacturer, making comfy homes since 1986
Glasswool batts
Pink, yellow or brown slabs cut to fit between the joists. Fibrous and itchy, with a visible seam every 430 or 580 mm.
Comfort Zone insulation.team
Family-owned insulation manufacturer, making comfy homes since 1986
Polyester batts
White or off-white slabs, more like a thick blanket than a fibre mat. Not itchy to handle.
No photo off our own jobs
Rockwool
Mottled dark grey-green, noticeably denser and heavier than glasswool. Comes as batts or as loose fill. We rarely see it in a Queensland ceiling. And I don't have a photo of one off our own jobs, so I'm not going to borrow someone else's.
Insulation depth to R-value
Find your measured depth, read across to your material.
This assumes the insulation is in good order and covering the whole ceiling. The two sections after it deal with what takes the number back down.
| Depth you measured | Cellulose | Rockwool | Glasswool | Rockwool | Glasswool | Polyester |
|---|---|---|---|---|---|---|
| blown in | blown in | blown in | batts | batts | batts | |
| 50 mm | R1.25 | R1.32 | R1.19 | R1.25 | R0.86 | R0.83 |
| 75 mm | R1.88 | R1.97 | R1.79 | R1.88 | R1.34 | R1.29 |
| 90 mmlevel with a typical joist | R2.25 | R2.37 | R2.14 | R2.25 | R1.61 | R1.55 |
| 100 mm | R2.50 | R2.63 | R2.38 | R2.50 | R1.79 | R1.72 |
| 110 mm | R2.75 | R2.89 | R2.62 | R2.89 | R2.08 | R1.96 |
| 120 mmwhat we pump as standard | R3.00 | R3.16 | R2.86 | R3.16 | R2.26 | R2.14 |
| 150 mm | R3.75 | R3.95 | R3.57 | R3.95 | R2.83 | R2.68 |
| 175 mm | R4.38 | R4.61 | R4.17 | R4.86 | R3.37 | R3.43 |
| 200 mm | R5.00 | R5.26 | R4.76 | R5.56 | R3.85 | R3.92 |
| 250 mm | R6.25 | R6.58 | R5.95 | R6.94 | R5.21 | R4.90 |
| 300 mm | R7.50 | R7.89 | R7.14 | R8.33 | R7.50 | R5.88 |
What that 90 mm row is telling you
Most Queensland ceiling joists are about 90 mm. If your batts are laid between them and finish level with the top, you are on that highlighted row: glasswool batts are about R1.61 there, and polyester about R1.55. That’s a long way under what you’d want in this climate, and every joist is bridging heat straight past the insulation on top of it.
At that same 90 mm, blown cellulose is about R2.25— roughly 40 per cent more, out of the same depth — because loose-fill conducts heat more slowly than a batt does. Pump it to 120 mm, which is what we do. It’s R3.0 while a glasswool batt at that depth is still only R2.26. That gap is the whole reason we pump instead of cutting batts in.
How these numbers are worked out
R-value is thickness divided by thermal conductivity. For cellulose we use CSIRO’s figure for loose-fill: 100 mm = R2.5, which is a conductivity of 0.040 W/mK. The other materials use the conductivities published in the batt industry’s own assessment guide (see below). Blown-in products hold one conductivity at any depth, which is why those columns rise in a straight line; batt conductivity shifts with thickness, so the batt columns don’t. Real products vary, so treat these as a good working estimate rather than a certificate.
Worth more than depth
Why gaps cost you more R-value than depth ever will.
The table above assumes full coverage. Almost no batt ceiling has it. Here’s what happens to 200 mm of glasswool as the bare patches add up — and these are the batt industry’s own published figures, not mine.
| No gaps at all | R3.85 |
| Slight gaps, poor fit (3% of the ceiling) | R2.70 |
| Obvious gaps, loose fit (6%) | R2.05 |
| Large gaps, missing insulation (12%) | R1.34 |
Same batts, same depth. Twelve per cent of the ceiling left bare and nearly two-thirds of the value is gone. And the bit that catches people out: the penalty gets worse the thicker the insulation. The dearer the batt, the more a gap costs you.
Who those figures come from
They’re from the Insulation Council of Australia and New Zealand, which is the trade association for the batt manufacturers. The only three brands named in their own guide are Fletcher Insulation, Bradford and ROCKWOOL — glasswool and rockwool makers. No cellulose manufacturer is in it.
So read them the way I do. On what gaps do to a batt ceiling, that’s the batt industry testifying against its own product. It’s worth quoting for exactly that reason. On anything comparing batts to pumped-in products, they are not a neutral umpire and I wouldn’t treat them as one. For cellulose I go to CSIRO instead.
The question everyone asks about loose-fill
Does blown-in insulation settle, and does your R-value drop with it?
Short answer: it settles a little, almost all of it in the first day. The R-value holds up better than the drop in depth suggests. Here's why.
CSIRO say loose-fill may settle over time and that installers should allow for it. Where I’d part company with them is on the timing. In my experience making and pumping this product, at the depths we install, it does about 90 per cent of whatever settling it’s going to do within a day of going in. It isn’t a slow sag over twenty years.
What does move it is moisture. Cellulose takes up atmospheric moisture, and under a tile roof a rain event pushes a load of damp through the cavity. That weight presses the blanket down a little. It’s the same thing that flattens fibreglass batts in those roofs, and it’s worth knowing rather than pretending it doesn’t happen.
The bit that gets left out: settling makes it denser
Everyone treats a 10 per cent drop in depth as a 10 per cent drop in R-value. It isn’t, because the same material is now packed into less space. Cellulose has a density where it performs best, and a pumped ceiling that settles slightly moves towards that point rather than away from it. The fibre conducts heat a bit more slowly at the higher density, which offsets most of the thickness you lost.
That’s the practical difference between loose-fill settling and a batt going flat. A squashed batt is just a thinner batt. Settled cellulose is a denser blanket, and density is working for you.
It’s also why we pump to a settled figure rather than a fluffed-up day-one number, so the R-value you were quoted is the one you keep. The longer answer on settling, including CSIRO’s own 1996 letter on it.
Before you trust your number
Eight reasons your real R-value is lower than you think.
These are the differences between a measured ceiling and a labelled one.
The R-value printed on an old batt is not what it's doing now
That figure was measured on a brand-new batt at full thickness, fitted with no gaps. Twenty years of foot traffic, sagging, and other trades shoving it aside, and it isn't that any more. Measure the depth and read the table. The label is history, not a measurement.
Measure the depth, not the width
Batts come 430 mm or 580 mm wide to suit joist spacing. That has nothing to do with R-value. Thickness is what insulates.
Two layers don't simply add up
If someone has topped over an old job, work off the top layer only. The bottom layer has usually compacted. Adding the two labels together gives you a number your ceiling isn't delivering.
If it's below your joists, you're under R2
A typical ceiling joist is 90 mm. If the insulation sits level with or below the top of it, look at the 90 mm row: batts are around R1.6 there. If you can see the joist tops standing proud like stripes, that's your answer before you even measure.
Anything squashed is doing almost nothing
Crushed under a stored box, a walkway board or an air-conditioning duct, insulation loses most of its value at that spot. Loft it back up if you can, and don't store things on top of it.
Measure in three or four places, not one
Insulation is never even. Take readings near the manhole, out towards the eaves, and in the middle. If they're wildly different, that variation is itself the problem worth fixing.
Don't fill gaps around fittings without checking first
Downlights, exhaust fans, heater flues and chimneys all need clearances, and old wiring may not be rated to be covered. Check before you reduce a clearance around anything electrical.
Vermin mess means it comes out, whatever the depth says
If there are droppings and nesting through it, the R-value is beside the point. That's a removal job before anything new goes in.
So how does your number stack up?
Is your ceiling insulation enough for South East Queensland?
Brisbane and the coast
R2.5
Climate zone 2. The Code baseline for a vented roof with reflective sarking. A darker roof, or one that doesn’t vent or isn’t sarked, wants more.
Toowoomba and the Downs
R3.0
Climate zone 5. Colder winters, so the baseline sits higher than the coast.
Nobody is making you do anything
Those Code figures apply to new building work, not to a house that’s already standing. The ABCB say it themselves: existing homes don’t need to meet current NCC standards unless new building work is done. Measure R1.5 up there and you’re not breaking a rule. You’re just paying more than you need to for cooling. And these are minimums for the insulation itself, not a whole-of-roof figure.
Want the number for your exact suburb rather than a rule of thumb? The R-value lookup works it out from your climate zone, and the climate-zone guide explains the six things that shift it.
Straight answers
Measuring your ceiling insulation: the questions I get.
How thick should ceiling insulation be in Brisbane?+
For blown-in cellulose, about 120 mm gives you R3.0. That's what we pump as standard across South East Queensland. The National Construction Code baseline for climate zone 2 is R2.5 for a vented roof with reflective sarking, so 120 mm puts you over it. Toowoomba and the Darling Downs are climate zone 5 where the baseline is R3.0. Batts need noticeably more depth for the same number, because most of them conduct heat faster than loose-fill: a glasswool batt is only about R2.26 at 120 mm.
How do I find out what R-value my ceiling insulation is?+
Measure how deep it is with a ruler, work out what it's made of, and read it off the table on this page. Depth is what does the insulating, so a measured thickness plus the material tells you far more than a label on a twenty-year-old batt. Measure from the ceiling surface, not the top of a joist, and take readings in three or four spots because insulation is rarely even.
My batts are level with the joists. Is that enough?+
No. A typical ceiling joist is 90 mm, and glasswool batts at that depth work out around R1.61. Cellulose at the same 90 mm is about R2.25, roughly 40 per cent higher, because loose-fill conducts heat more slowly than a batt does. Either way, level with the joists is well under what you'd want in a Queensland ceiling, and it means every joist is also bridging heat straight through. That's the classic case for topping over the top rather than starting again.
Does the R-value on my old batts still apply?+
No. It's the thing that catches most people. The printed figure was for a new batt at full thickness with no gaps. Once batts have compressed, sagged, or been pushed aside by an electrician or air-conditioning installer, your ceiling isn't delivering that number. Gaps hurt more than most people realise: on the batt industry's own published figures, 200 mm of glasswool falls from R3.85 with no gaps to R1.34 with large gaps. Same batts, nearly two-thirds gone.
Do I legally have to upgrade my ceiling insulation?+
No. The National Construction Code applies to new building work, not to a house that's already standing. The ABCB say it themselves: existing homes don't need to meet current NCC standards unless new building work is done. So nobody is breaking a rule with an old, thin ceiling. Those figures are just a sensible benchmark for what's worth having in your climate.
Can I just add more on top of what's already there?+
Usually yes. It's normally the cheaper option. If what's up there is dry, sound and free of rodent mess, we pump cellulose straight over it, which fills the gaps the old batts left and covers the joists at the same time. It has to come out first when it's wet, rodent-fouled or broken down to debris. I'll tell you which your roof needs when I quote, and removal is quoted as its own line so you can see what you're paying for.
Measured it and it’s thin?
Send me the number and I’ll tell you what it’d take.
Most roofs get topped straight over what’s already there, which fills the gaps the old batts left and covers the joists at the same time. Fixed price by email, usually within 48 hours, no deposit and no inspection to book first.
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