We hate the look of it as it has been installed centrally and only set back an inch or two from the edge of the roof. The walls will be dark grey colorbond and it will look like the knob on a sugar bowl. We cant see it venting much, only the area between 2 rafters as there is no ceiling cavity.

Which 'code' is he quoting?

An appropriate build-up of insulation between rafters and on their underside will give you a much more comfortable home.

The whirlybird will only be able to extract air from the cavity it draws from....

The code of the "dont you worry your pretty head because I've built 100 hip roof brick veneer homes with these things and I'm the expert" unhelpful building supervisor.

sounds like you need a new builder..from experience they don't deal very well with females mine had the cheek to tell me he can't move the rangehood..and got my husband to talk me around the rangehood being 5cm from the edge of bench as I'm short so it wouldn't matter..I wouldn't bump into it ..

stick to your gun get a second opinion..I stuck to mine and he had to remove the rangehood and reinstalled it again..as he's done it already..I was fuming..

I'd be going back to the architect/designer and asking why the vent wasn't on the plans then armed with that info, I'd be asking your Turkey of a Supervisor why if it wasn't on the plans he didn't flag and insist on being given the EXACT code that he's referencing (including the details so that you can review yourself) as last time you checked YOU WERE THE CLIENT - It's a shame you've had this happen - your home looks as though it will be stunning, but others have said it wont be so noticeable when the building is done completely.

The placement kind of makes sense since heat rises so you'd want it to be as close to the highest point for maximum effectiveness but you should have been aware. Check on the builders itemized estimate to make sure that you didn't miss it by accident so that if you did accidentally miss that one line item on a list of a million you able to prepare your argument accordingly.

I am the designer (amazing what you can achieve with google sketchup) but engineering and codes were not my department. I took my initial designs to an architect but he just redrew them with a better program and charged me $4000 with another $4000 needed to add the engineering specs. The other problem was the architects drawings looked so good no builder would quote us a reasonable price, so I took a basic hand drawn floor plan and elevations to a volume spec builder who advertised they could also do custom builds on steep sites. For $2000 they got the plans drawn up and the structural engineering BAL and energy ratings completed and quoted a good fixed price. The problem is, even though they are excited at building a contemporary home, the majority of the work they do are brick veneers on housing estates. Design details just aren't a priority.

The whirley bird is on the building companies list of standard inclusions others are things like garage rollerdoors and we dont have a garage! We have decided we are not adverse to having it (especially as so many of you have said it is not that noticeable and I love eco features) but I still would be interested in any builders/architects or engineers opinions about the merits of having one venting a skillion /raked ceiling roof cavity.

Ah OK. Then I'd be taking the Supervisor offsite for a coffee and asking EXACTLY what building code this is covered as you're really not happy with the "pimple look" and want to see what options are available to you. I'd also say that I was asking him out of respect for his experience and would very much appreciate him affording you the respect of professional replies to your questions as you're the paying client. You might not win this one, but you'll have set the tone - that attitude even if he is an expert is unprofessional. I'd also call his boss and point out the issue(s) - they'll use your home to advertise how great they are - let them earn that right.

We just need to choose our battles. Our first problem was a lintel where a highlight window appeared on the plan. The supervisors initial reaction was to say the window was not possible. We won that one and are getting thinner steel lintel which leaves room for the window. We don't want to hold up the build at every stage. I like your point about involving the boss. I'm sure the finished house will take pride of place on his website.