Is a double layer of r1.5 = r3

Well looks like I will be installing more insulation then....how expensive is this stuff?

Cobber
Based on your locality being Esseindon (closest to) your ceiling is R2.5 for heating only and R3.0 for heating & cooling.

Your walls are R1.5 for Brick veneer or R1 for cavity brick

Thes figures are directly quoted from the Standard and as previously said are the minimums.

Prices are based on what type of insulation you buy. I went for poly batts cause there is no irritants in the material and I store stuff in the ceiling space. Also at this point in time there is no need to wear breathing gear (roof space is clean now) when working with this stuff.

With poly batts I paid about $55 per bag which is 8x R3.2 batts 560mm x 1200mm and about $50 per bag for 16x R1.5 batts at the same size.

Ok I think I need to clarify some things here

1. I asumed that common sence would prevail in regards as to what I meant by put in what you can afford.... I meant that if you can afford it put in R5's cos they are the best. But if you can not afford to put them in then put the highest posible r rated bats you can. Pointless paying $2500 to put bats in if it means you are going to go without food for the next month cos you want the best insulation money can buy.

When I put insulation in my roof R5's were 42.00 a bag and R4.5's were half that. So it is a money insue when you start talking that kind of jump in price, and excuse me if I prefer to set myself up above the Australian Standards (or am I just being stoopid).

Wall insulation, unless you want to pull off all the interior gyprock skin and put in R1.5's is worthless. That pumped in rockwooll is crap. Yes you will get some insulation from it but do the costs make it un feasible....

One last comment. As I understand there are a hell of a lot of houses in this coutry that are pre- 1980 ... should we not insulate these houses or are we wasting money???

Have a lovely day

Pete

Doughboy
To answer some of your comments:

It's not necessarily best to exceed the standard by large quantities either. Think of the current weather, it was 3 deg C at home last night and the house would have eventually got down near that level early this morning without any heating. Now its 20 deg C but the house is still dead cold from last nights temperature thus requiring heating to bring it up to a comfortable level. From my view you can exceed the standard by a small level to gain economies in purchase but to exceed the standard by large ammounts may still be wasting money.

As to costs per bag. Insulation all comes in about the same size bag - to fit through the average roof access.
What changes is the thickness of batt compared to the number of batts per bag, ie 16 of R1.5 or 8 of R3.0 or 5 of R5.0. The higher the number the less batts per bag. This is based on assuming the R level of each material is basically similar. The difference between R4.5 and R5.0 may be one of economies where there are very few people who use R5 for much of this material to be made, hence the higher price. But if you were in an area which required R5.0 (can't say I saw anywhere where you needed this level of insulation, but the Standard didn't include Maquarie Island) you'd be silly not to use it. You need to work out the comparitive costs on a square metre basis - not on costs per bag.

With regard to rockwool - Have you seen this site??
http://www.ais-group.com.au/homeinsu...ive_survey.htm
Rockwool is actually listed as number 1 (best) in this survey based on scientific principle.
Personally I won't use rockwook because of the irritants in it but thats my issue and not a recommendation. Rockwool doesn't lend itself to brick veneer due to the gap in studs needing to be filled. It packs down and you end up with only half a wall which then needs refilling. So you get them out twice - you just need to expect that.

The reason I quoted 1980's is that was generally the end of the period where fibro and similar materials were discontinued and the brick veneer house was the norm. Pre 1980's where the house is fibro can have ceiling insulation but to work on the walls brings up the issue of asbestos. Might be cheaper to knock down the whole house and start again or use cladding type materials with polystyrene foam on the inside. With pre 1980 houses you also has issues with cabling in the roof where you need to have the insulation batts or similar under the wiring otherwise you risk the cabling overheating which may result in a roof fire.