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Insulation is a vital ingredient in achieving thermal comfort year round. In a >9 star development like Bull Street Terraces an accurate amount of the appropriate insulation in the perfect place is vital. But what is the insulation made from? Where does it come from? Are some choices healthier than others?

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Generally Accepted Process

R3.5 Rockwool or Polyester Bulk insulation and Foil Sarking to Roof.

R1.5 – 2.5 Rockwool or Polyester Bulk insulation and Foil Sarking to external walls.

Building to be generally air tight.

Choices For Bull Street

Roof Insulation

Expanded Polyester Batts

To achieve the 9 Star rating  the building will require R6 bulk insulation plus sarking to the roof. Above the stairwell R8 is needed.

To minimise condensation, sarking will be installed under the insulation (on the warm side of the insulation) with 20mm natural sag and foil side down to the air gap in the ceiling battens.

R2.7 to Ceilings below 1st floor.

(NB: a R4 batt with a R2 batt will result in a slightly lower R rating as the top batt will compress the lower one reducing its designed depth – Compression of more than 10% reduces the Rvalue. If the top batt were suspended somehow this would negate this argument and could even introduce an air layer, further improving the insulation properties).

Wall Insulation

Expanded Polyester Batts

To achieve the 9 Star rating  the building will require R 2.7 and anti glare foil to the external timber cladding of the Rammed Earth Walls.

Slab Insulation

To achieve the 9 Star rating the building will require R1 slab insulation to the full depth of the perimeter.

NPS 50mm SL grade Expanded Polystyrene to slab edge perimeter to continue full depth of external edge. (Manufacturer & supplier: NPS Sunshine – Paul 03 8326 8080. N.B. Seconds may be available)

A separating film to be placed between the polystyrene and the cement to make future recycling possible.

 Summary of Reasons

We have chosen to use Expanded Polyester Batts in the Bull Street project as added formaldehyde, present in Glass Wool Batts, is a Red List product and its use prohibited if an alternative is available.

Glass wool products come from a slightly better ‘womb’ as they are from recycled glass rather than recycled plastic (petrochemical).

Glass is resourced and processed in Australia, so manufacturing miles are less than Polyester which is Post Consumer Waste collected world wide, sorted and primarily processed in Asia and China and imported for Manufacturing in Australia.

Green Tag certification: Bradford Gold (glass wool) has Level B and Tontine (expanded polyester) is Level A Gold.

Pink Batts are GECA certified. According to the Pink Batt (glass wool) MSDS (material safety data list) the product has 2 – 16% heat cured phenol- formaldehyde resin.

Polyester Batts have no resins.

In the EU formaldehyde content has been limited to 0.02% so there is an alternative. Earthwool (made from glasswool) has no added formaldehyde but has high transport miles as it is manufactured in Europe or the Middle East.

Bradford Gold cost less than Pink Batts but are manufactured in Sydney rather than Dandenong.


Details of Research

Natural wool (ref: Choice Magazine, Tania Fong 2010)

Natural wool is sold as batts, blankets or loose fill. Experts say wool is a niche product in Australia although it’s more popular overseas. Batts are usually wool blended with polyester, which helps them keep their shape. It’s recommended you choose batts that are 70% wool as these are more likely to be fireproof.

In CHOICE tests in 1997, some wool batts failed fire-resistance tests, so ask for assurance that it’s been adequately tested, preferably to the more stringent British Standard 5803 part 4. Also check the insulation has been treated to permanently resist insects that can breed in unprotected wool insulation.

Wool is usually more expensive than other insulation. If used as a loose fill it must be thoroughly scoured and treated with insect repellent and fire retardant.

Tontine Insulation  – Green Tag – gold, level A

Manufactured in Coburg, Melbourne. Ahley Gaspero 0412 016 863 for supply Mario 0422 000 524 for info (informative and personable). Available from Beards (3.5km from the site).

Raw material sourced from PET – post-consumer plastic processed in Asia and China, baled and shipped to Australia where is it processed into batts.

Products were rated for Health and Ecotoxicity, Biodiversity, Life Cycle Assessment score, GHG and Social Responsibility.

The products achieved a rating of 0.0 for Health and Ecotoxicity meaning Tontine insulation has virtually no chemicals or toxins harmful to health. This is particularly beneficial for buildings where allergy or asthma sufferers are a concern.

Tontine Insulation is committed to producing environmentally friendly insulation to ensure the sustainability of the environment. This commitment extends throughout the supply chain and includes eco friendly insulation production processes, selection of materials, distribution network, and the recycling of manufacturing and/or product offcuts. However it is a petrochemical product. It has Green Tag certification which is largely based on its LCA (life cycle analysis – cradle to grave) however we are struggling to get clear answers on its ‘cradle’.

Min. 80% recycled polyester fibre used in production of Tontine Insulation’s environmentally friendly insulation. All of Tontine Insulation’s Thermal Insulation & Acoustic Insulation products are recyclable.

R4 Insulation Batts nominal thickness 200mm. 4 in bag $35.45. covers 2m2 = $17.72 per m2

R3.5 Insulation Batts nominal thickness 190mm

R3 Insulation Batts nominal thickness 175mm

R2 Insulation Batts nominal thickness 90mm. 12 in bag $50.15. covers 6m2  = $8.35 per m2

to achieve R6 365mm roof space needed (R3 + R3.5)

to achieve R8 400mm roof space needed

Ceiling load of R4 = 2.2/2.4kg m2

Price: comparable to glass fiber for wall insulation but about 20% more expensive for the thicker ceiling batts.


BRADFORD GOLD Australian owned – Green Tag – level B

Bendigo office 03 54433777 – (Richard, very helpful & informed)

Distributed locally by Skinners Gyprock in Eaglehawk, Marybourough (54642357) or Ballarat.


Manufactured in Sydney, made from glass wool with up to 65% recycled content (recycled glass) they also produce a polyester batt but claim the glass fibre batt has a better LCA as it is manufactured from glass, not a petrochemical.

R2.5 nominal thickness 140mm.  $44 covers 9m2 = $4.8m2

R3.5 nominal thickness 185mm.  $49.90 covers 9m2 = $5.54m2

R4.1 nominal thickness 210mm.  $39 covers 5.6m2 = $6.96per m2

R6 nominal thickness 260mm.  $48.80 covers 4.5m2 = $10.84m2

Producing an R7 batt in Oct 2013 nominal thickness 275mm

Bradford Gold and Pink Batts are the only two glass wool batts products available in Australia

Bradford claim theirs is a finer fibre making it softer to touch.

Pink Batts new generation is ‘now with softer feel’

Bradford have bought Tontine and Martini, two companies which manufacture expanded polyester batts.


Pink Batts – NZ owned
Manufactured in Dandenong and distributed to the whole of Australia and NZ from there.

Made from Glass wool from recycled glass and resins.

According to the Pink Batt MSDS (material safety data list) the product has 2 – 16% Heat cured phenol-formaldehyde resin!

In the EU formaldehyde content has been limited to 0.02% so there must be an alternative and we will contact Fletcher Insulation manufacturers and suggest the alternative when we find out what it is.

  • GECA certified
  • Can be recycled – melted back down and re-formed.
  • Higher R value/depth than expanded polyester

To achieve R8 put an R6 batt under and the lighter R2 batt over to minimise compression of lower batt to less than 10% (at which point it’s R value is compromised)

All Pink Batts are produced over their stated R value so an R2 may test at R2.02 etc so slight compression will fall within the tolerance and still give the desired R rating.

(The industry practice is to have a 5% tolerance above or below, Pink Batts only produce above.)

As far as I have found out the actual production process may take more power but produces more product in a shorter time. I have not made an analysis on how the two techniques compare in terms of power usage.

Available from Beards hardware (3.5km)

R2 nominal thickness mm – 24 in bag $58.30. covers 12m2. $4.85 per m2

R4 nominal thickness 175mm – 1160×430 10 in bag $51.25. covers 5m2. $10.25 per m2

R5 nominal thickness 215mm

R6 nominal thickness 250mm