Thanks for this forum - a great source of information. Short time lurker, first time poster: I tried Whirlpool forums, but no response to my very specific question as yet.
We are renovating our house and the amount of options and variety in insulation options is hard to work through. I've read the very useful yourhome.gov section on insulation and passive design now numerous times.
The new section of roof is colorbond (light colour) and relatively flat fall, with a shallow roof space (about 500mm). The roof will get anticon underneath, then have some air space and I'll put large bats in above the ceiling.
We have large areas of glazing, so are not kidding ourselves that this place is full enviro-friendly, however am keen to do what we can within our envelope
Now, there is one section of ceiling that is lower than the rest, and has a lot less insulation potential, and I am keen for opinions:
From bottom to top it goes something like this:
140mm joists, yellow tongue directly on joists with colorbond sheet metal gutter directly on the yellow tongue – no sarking, blanket or anything.
GIven I have 140mm joist space to play with – what is my best option?
Do i try to from the underside, put some vapor permeable sarking in between each joist to reflect some radiant heat? and with my limited space jam battinsulation up against it?
Or forget the sarking and go straight bats. I'd be somewhat worried about condensation UNDER the yellow tongue causing it to rot?
Any ideas welcome.