Alternative Technology Assn Forums

1. 

   Annette
   Member

   Hi

   Advice requested on rockwool vs. fiberglass batts

   I am tossing up between 70mm R2.1 fibreglass Sono Batts from Pink Batts and 75mm R2 Bradford soundscreen batts for my ceiling. Both are acoustic rated with a density of 32 kg/m3. The thermal property is the important thing (but acoustic seem to have higher R values per centimetre)

   I can only fit 70 - 75mm (not a typo!) and still leave an air gap under the roofing foil.

   I have to decide soon as I had arranged insulation with the Sono Batts under the rebate and now the installer has offered to deliver them for free (25 bags for $1,060. It's $49.50 a bag, retail, so only about $220 cheaper) to get them out of his warehouse. I can't justify the cost of them doing the installation so will do it myself, bit by bit.

   I have discovered that Bunnings can supply the same amount of Bradford Soundscreen rockwool batts for just $44 dollars extra. So I am now considering whether to go for those instead and just buy them in 2 or three lots as I go to save space. The Bradford are water repellent.

   I look forward to your advice/opinions.

   Posted Tuesday 23 Feb 2010 @ 4:39:09 am from IP #
2. 

   ghostgum
   Member

   My experience is:
   Polyester batts are not itchy
   Rockwool batts are slightly itchy
   Fibreglass batts are more itchy

   You can get higher R values using 25mm polystyrene, but this will be more expensive and may be trickier to install without gaps.

   Posted Tuesday 23 Feb 2010 @ 5:17:26 am from IP #
3. 

   cool at home
   Member

   Don't get put off by foil - the Air cell foil is a really good product for tight spaces. But you would need to use a good installer, so possibly not ideal if you are trying to keep cost down.

   Poly batts are considered low allergen, and many with young children or asthmatics in the house prefer this. It is about 30% dearer than equivalent products in fibreglass.

   Posted Tuesday 23 Feb 2010 @ 7:35:52 am from IP #
4. 

   Annette
   Member

   Thanks for that, Cool at Home. I talked to the people at Air Cell last year but they said I wouldn't get a very good result since I am retrofitting in the long pockets in my raked ceiling formed by the hardwood rafters (no battens) and the rare beam.

   This means that I would have to staple it halfway down the rafter (between the foil roofing blanket and the bottom of the rafters, where the plasterboard would sit) to keep an air gap both sides and it would be hard to make it airtight at the edges. They said laying under the roof is really the only way to go to get their advertised R values.

   I then got a quote from the roofers of just over $4,000 to remove the colourbond, roll up the existing 55mm roofing blanket, lay aerocell 'with no gaps' then relay the blanket on top (thereby reducing the R value of the Air Cell!). Might have considered it, but these were the people who left huge gaps in the roofing blanket 4 years ago(that I only saw when the recent reno started)as well as putting the wrong colour roof on. I had thought they might give me a discount as they had to come back and fix the shonky insulation by lifting the roof anyway - but no deal there! None of the other roofers I called were interested in quoting.

   Recently, I also investigated having a layer of foilboard pushed against the bottom of the rafters onto the Rondo roofing clips used for a suspended ceiling - with the plasterboard then attached below the foilboard. It would lower my ceiling by 60mm or so but give a good R value result because of the 90mm air gap. However, the plasterer hasn't got back to me with a quote so have no idea of the cost (possibly this is a sign that it is really $$$$$$).

   Has anyone done this for their ceilings or walls?

   Posted Tuesday 23 Feb 2010 @ 9:15:49 am from IP #
5. 

   greenvalue
   Member

   My advice: it crude, but right now it might be better to wait a week or two!
   You might have insulation people running your door in (since you want to pay for the job) just so they can lower their excess stock and pay some bills...

   I'm also an advocate for FOIL, followed by polyester! Personally I don't trust that the dust of other insulation won't creep through cracks. And there is a health risk, even higher if you want to install the insulation yourself...

   Posted Tuesday 23 Feb 2010 @ 9:34:03 am from IP #

RSS feed for this topic