I converted my double garage into a theater room, it is 6x5m with a vaulted ceiling. I built a 75mm wall just behind the roller doors they face north, gyp-rocked and insulated it, the east and west walls are double brick, the southern wall is single skin brick, no windows at all, just a blacked out skylight.
I kicked up the roof tiles and basicaly stuffed the 250mm cavitys full of wool insulation with the foil on it, just stuff i accumulate out of work site bins, mostly left the stuff rolled up cause i couldn't be bothered cutting it.
It gets hotter than the ninth level of hell in there in summer, was that reflective stuff rolled up like that a bad idea?
should i pull em all out and just install normal roof bats? or install a whirlybird for more ventilation