Our top floor gets hot despite having - 'on paper' - very good roof and wall insulation, windows, external canvas awnings, timber venetians and thermal curtains - all used very well 'granny style' (ie: closed on the sunny side then opened, thermometer to tell us when it is hotter inside than out so to open windows etc). But we don't have access to breezes due to our location and a problematic floor plan (although we were smart enough to put the bathrooms on the west, with 2 bedrooms facing north, one facing south).
We thought of venting the bedrooms directly outside, and put 1 closeable ceiling vent in each and 2 Supavents on the roof. This cut holes in the insulation (yes I know... everyone say 'doh' with me), so the vent covers are hot to touch and the top floor is still hot. Not a success at all, as far as we can tell.
We are now tossing up between:
1. Closing the ceiling vents and putting insulation back over the top, and top up the existing insulation from current R3.5 (batts plus sarking installed 7 years ago) to R4.5 (or higher) with Air Cell laid over the rafters
2. Extract air from the attic with a motorised vent (eg: 2 x Maestro), so that air is also drawn out of the top floor bedrooms - equivalent to 8 Whirlybirds, apparently. Could also top up the insulation...
3. Duct the ceiling vents directly to the outside with 'Vent a Room' kits or similar. Note that these 'whirly birds' are not powered, so I'm not at all confident they will get much air flowing. Of course, could still easily top up the insulation.
I believe far more in insulation than whirly birds (which I generally consider a supported employment program for aging tradespeople) but feel we lack good ventilation and need to solve this. Can't work out how to put windows in for cross breezes given the placement of internal walls.
Has anyone solved this problem? If so, how?
Has anyone out there had experience of the (mains powered) Maestro, with a view to how effectively it will draw air from the top floor and through the attic?
Any ideas I haven't thought of, but should?
Would really appreciate your comments.
Thanks
Susan