# Forum Home Renovation Roofing  Deck roofing - insulation/insulated colourbond

## Zoe

Hi all, 
I was wondering if I could get some feedback on the idea of insulating a colourbond roof we may have built over our deck when we get it done. 
It is in a VERY hot location in summer (west facing with no shade at all). 
I was wondering about the ease of insulating an already made roof, or if it is better to do it as the roof is built, or if maybe there is such a thing as 'insulated colourbond'? 
Hope to hear from you guys soon, 
Many thanks, 
Zoe.

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## woodbe

Not quite, but close... 
Check out Bondor 
It's the same stuff as coolroom panels - can be bought in various thicknesses. No problems with using it as roofing. 
Under a veranda roof, you are probably mostly subjected to radiant heat. You could just go with plain colorbond in white, and have sisalation as a radiant barrier below it. Should work well.

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## Zoe

> Not quite, but close... 
> Check out Bondor 
> It's the same stuff as coolroom panels - can be bought in various thicknesses. No problems with using it as roofing. 
> Under a veranda roof, you are probably mostly subjected to radiant heat. You could just go with plain colorbond in white, and have sisalation as a radiant barrier below it. Should work well.

  Hey - thanks for your reply. 
Not wanting to sound ignorant (even though I probably am! :Doh: ) but could you explain further about the use of 'sisalation' as a radiant barrier?  What exactly is this and how does it work? 
Thanking you  :Smilie:

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## SilentButDeadly

Sisalation is the brand name of a range of building membranes.... 
Under a tin roof it might be effective as a radiant barrier except that according to the Insulation Council it has an R value of zero when used in conjunction with metal roofing/walling.....so quite how effective as a radiant barrier it actually is in this application seems to be open to question.

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## woodbe

SBD, you are confused  :Smilie:  
Do not confuse bulk insulation with radiant barrier! 
The purpose of bulk insulation is to reduce the thermal transfer between two spaces. Think 'conduction'. This is the sort of insulation you need when there is a big difference in temperature between the air inside and outside your home. Especially when you consume energy making the inside more comfortable. 
On the other hand, a radiant barrier is there to effectively reflect radiant heat away. It works just like that. The thin metal film applied to low-e glass is a good example of a non-sisalation radiant barrier. A shiny, mettalic surface is very effective radiant heat barrier. Ask a car racer why the highly polished camcovers are not used for serious racing - they look great, but they hold more heat in. 
The sun is our biggest radiant heat source. It heats the external faces of our buildings which then re-radiate that heat into the interior of the house. The purpose of the radiant barrier is to reduce that radiant energy. 
So the answer is, for a house with any sort of heating or cooling, you need both! 
woodbe.

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## woodbe

Also, a little bit of scientific backup. I think the Sisalation company probably has masses of this, but there was a test program in Florida where they retro-fitted a radiant barrier and measured the differences. Here is a link to the complete  FSEC Study 
Here is the chart of the first of a bunch of houses they tested:

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## barney118

The best insulation medium is air, depending on the temp you are talking about one option mentioned above is "builders blanket" various R levels available foil on one side and fibres on the other (sisalation product type). depending where you are depends on foil side up vs foil side down, sydney i'd say foil side down. (then use batts under and then ceiling to tidy up.
Alternate is the "coolroom panels" Lysaghts have a product foam in between steel sheets not sure what they call it similar sort of result. 
you'd be suprised the difference the sisalation provides, just re roofed my house and it had no insulation, for around $130 a 20lm roll (1200 wide) its probably the best value for $

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## Zoe

Gosh thank you all so much  :Smilie:  
There are a few more options than I first thought! 
I will try and do a little bit of reading on each of the different styles and see what I come up with. 
From the looks of things - I'm guessing you would all generally recommend the sisilation-type products over the insulated colourbond-type products? 
Thanks again peoples  :2thumbsup:

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