foil insulation works by have a low-emittance surface i.e. heat hits one side but is not emitted through the other. For this to work the foil needs an air space on the non-emitting side, if it is hard-up against something then it will conduct heat through that material, 20mm is enough. Bulk insulation (think fluffy batts) works by slowing down the flow of heat by making it move through a huge number of very small air pockets to reach the other side. In short, a well designed building will always have a combination of both foil and bulk insulation. Your climate will dictate the build up of the wall as you do not want to create a condensation problem within the wall itself. As chookchook2 asked, where are you?

We went with Monument and I am delighted. I was worried about it making the house hotter, but not at all as we added some extra insulation while the roof was lifted. We look over our roof to Mt Dandenong and it really feels like we are floating above the rooftops now (previously had a lighter color). I have also noticed there is far less glare being darker. Pic below is not my best shots ... but you get the idea. Forgot to add we also have a flat cliplock roof and used a combination of Monument and Dune on the house.

Hope you've been able to use all our inputs! I've never noticed the surfmist roof to be dirty looking - my neighbour is always swearing about the bird poo on her darker roof. The fence is a lot closer than the roof for noticeable bird doings, lol. It's not quite white, anyway, it's got a silvery off white thing happening. Our winters don't really get below 1 or 2 c at night and that's pretty rare. It's usually an average of 7 or 8 degrees at night and 14 to 16 in the day. It's very Mediterranean - long hot summer and short wet winter... The winter is pretty mild altogether... I'm still working with some succulent cuttings at the moment. Our winter would be like an Autumn in say, the UK? Our Autumn time in Adelaide is when we plant a lot of stuff that others would put in in spring. Otherwise they just fry and die if spring planted, the UV is insane, they need winter to acclimate. Our grass is dead in summer and grows in winter... backwards! When we built I did a cactus and succulent yard with no lawns - grass is black hole to put money in, down here!

Has anyone had any experience with insulated roofing panels? There seems to be a huge difference in price for these panels. Stratco etc are $150.00 lineal metre as against $40.00 lineal metre for chinese sellers. Just wondering what the difference in quality is. Anyone used the cheaper ones?