Which R value for insulation?

[Wolfs]

I want to insulate my galvanised iron workshop, is R 3.0 good enough or do I need higher rating bats for it to be effective

[patty]

What do they say the fatter the bat the better and the higher R value the thicker the bat

[Barry_White]

R3 Insulation batts will give excellent insulation against heat.

[peter_sm]

Just as an extension on this question. I have a weatherboard garage with 90mm stud walls. The North wall is colorbond clad. I will be lining it with fibre cement sheeting.

What is the thickest bat that will fit in the wallspace?
in fibreglass?
polyester?
Which is cheaper?

I would think the fibreglass is itchier, but I have disposable full dustsuits I can use.

[patty]

Table 2: Insulation thickness for some specific R-values

<TABLE cellSpacing=1 cellPadding=3 width="80%" border=0><TBODY><TR><TD></TD><TD vAlign=top bgColor=#f2f2f2 colSpan=2>

Thickness required to achieve

</TD></TR><TR><TD vAlign=bottom bgColor=#ffffff>Material</TD><TD vAlign=top align=middle bgColor=#cccccc>R = 2.5 (mm)*</TD><TD vAlign=top align=middle bgColor=#cccccc>R = 3.5 (mm)*</TD></TR><TR><TD bgColor=#cce5ff>Glasswool batt (low density)</TD><TD vAlign=top align=middle bgColor=#cce5ff>130</TD><TD vAlign=top align=middle bgColor=#cce5ff>180</TD></TR><TR><TD bgColor=#ffffff>Glasswool batt (medium density)</TD><TD vAlign=top align=middle bgColor=#ffffff>100</TD><TD vAlign=top align=middle bgColor=#ffffff>140</TD></TR><TR><TD bgColor=#cce5ff>Polyester batt (low density)</TD><TD vAlign=top align=middle bgColor=#cce5ff>160</TD><TD vAlign=top align=middle bgColor=#cce5ff>220</TD></TR><TR><TD bgColor=#ffffff>Polyester batt (medium density)</TD><TD vAlign=top align=middle bgColor=#ffffff>110</TD><TD vAlign=top align=middle bgColor=#ffffff>160</TD></TR><TR><TD bgColor=#cce5ff>Sheep’s wool batt (low density)</TD><TD vAlign=top align=middle bgColor=#cce5ff>150</TD><TD vAlign=top align=middle bgColor=#cce5ff>210</TD></TR><TR><TD bgColor=#ffffff>Sheep’s wool batt (medium density)</TD><TD vAlign=top align=middle bgColor=#ffffff>110</TD><TD vAlign=top align=middle bgColor=#ffffff>160</TD></TR><TR><TD bgColor=#cce5ff>Sheep’s wool (loose-fill, low density)</TD><TD vAlign=top align=middle bgColor=#cce5ff>170</TD><TD vAlign=top align=middle bgColor=#cce5ff>230</TD></TR><TR><TD bgColor=#ffffff>Sheep’s wool (loose-fill, medium density)</TD><TD vAlign=top align=middle bgColor=#ffffff>110</TD><TD vAlign=top align=middle bgColor=#ffffff>160</TD></TR><TR><TD bgColor=#cce5ff>Rockwool batt</TD><TD vAlign=top align=middle bgColor=#cce5ff>90</TD><TD vAlign=top align=middle bgColor=#cce5ff>130</TD></TR><TR><TD bgColor=#ffffff>Rockwool (loose-fill)</TD><TD vAlign=top align=middle bgColor=#ffffff>90</TD><TD vAlign=top align=middle bgColor=#ffffff>130</TD></TR><TR><TD bgColor=#cce5ff>Cellulose fibre (loose-fill)</TD><TD vAlign=top align=middle bgColor=#cce5ff>100</TD><TD vAlign=top align=middle bgColor=#cce5ff>140</TD></TR><TR><TD bgColor=#f2f2f2 colSpan=3> </TD></TR></TBODY></TABLE>
Hope this helps price wise not too sure

[Chumley]

Hi all,

I did my 8 x 5m garage in my old house - I made a room 4 x 5m in the middle with a 2 x 5m 'dirty' storage are down the back and left the 2 x 5m space at the front as a garden shed (this had the tilt-a-door). I put a ceiling frame up with a 50mm gap to the flat metal roof and added stud walls with similar gaps - covered the outside of the frames with sisalation paper, then put batts inside the paper (with another small gap) and gyprocked it all up. I used R3 batts.

The research I did showed the R rating basically amounts to a time-factor, the higher the number the longer it takes to heat up. I used the sis paper mostly as a water barrier as the metal used to drip from condensation, but the double barrier worked very well - it was very cool in summer - I measure an 8 degree difference from the workshop to the dirty store.

Cheers,
Adam

[SilentButDeadly]

Fattest batt you'll fit in a 90mm wall without compressing the batt and therefore reducing its effectiveness is R1.5

If you buy anything thicker then you'll probably be wasting your money....

Glasswool batts are significantly cheaper than polyester.