Hi arcmaz Great house - fantastic 60's modern look - Harry Sidler (Modernist Architect 1923-2006 exponent of the Bauhaus style in Australia, mainly Sydney) would have loved the interpretation, its a good style, don't change it will pay dividends in the long run. It would be good if there was a plan of the house,and a plan of the block this would allow some relatively accurate planning proposals. If you had the real-state plan with the block plan it would help a lot. In terms of making the place bigger and retaining the style I would suggest that the extension (maybe one room and an en suite depending on a budget) be a block in the today's current style, but linked to the existing house via a "link" (Link =small walkway). This would allow you to retain the style, but not be dominated by a past period, I have done this a few times and it has worked fairly well. If you are looking for three bedrooms it might be best to add a master bedroom with a bathroom, and then maybe living areas with back yard access. There may be other approaches depending on the current layout that could be considered, but I would retain as much as the original as possible, and only make small cosmetic changes until you are ready for a worthy development. I hope this is of some help, I would be happy to comment further or work on this project. Regards - Michael Manias Manias Associates Building designers - mm407p@gmail.com

They look like steel doors but after a quick Google search nothing came up in Qld, only Melbourne and Sydney. I guess you'd already done this too hence your question. You could always order from interstate or maybe use aluminium instead. Maybe try a local heritage architect as they may have a local contact.

Hi Dr Retro, Thank you. I really appreciate the input and the time you've taken to explanation your point of view. I really do want to get an understanding of where the issues lie in this design. So I hope you'll forgive me digging a little deeper. I don't quite follow why you think the design would require a 6m lintel. Yes, it does require a 6m track, but the track can simply be attached to the wall. The weight of the door need not be supported by the top track. It could be supported from below. The whole point of putting the configuration on the outside of the wall is to minimize the need to make structural changes to the building. There currently is no capacity to install a 6m wide external sliding door/window unit. Likewise I don't follow why the door should be any draftier than any other external sliding doors. The cavity is on the outside of the wall, so draft is not going to get in via the cavity. Other sliding doors of the unit type have the same draft problems this configuration would and solve it by using an overlapping flange at the front end of the fixed door and the back end of the slider. The same could be applied here, where we treat the wall as the fixed door.The point at which the doors engage each other has also be solved for other door configurations. It is just a matter of having a loose tongue and groove configuration. Again this is exactly the same as a unit providing center opening sliding doors. Finally the same sliding mechanisms are used in other sliding door configurations, so I don't see why that should be any draftier here either.

I'd say it's an easy min. $250K minimum flagfall on a relatively basic/not fancy spec/fit-out in a super good package deal. You're essentially renovating an entire house including moving plumbing, walls replastering, new floors throughout etc....not to mention lights, rewiring etc etc, it goes on and on.......This scope would still cost a builder themselves $150K, not factoring in their own time/labour, paying cash for sub-trades and getting super deals on all materials....and then you could only really potentially roll this type of operation out if you actually have the money in the bank. If you need to borrow then you'd need a building contract which then brings in market rates, profit margins and GST. Take profit and GST out from $150K and there's barely enough left to cover materials alone, when the labour/materials ratio (of a construction cost) these days, particular for renovations is labour being the most significant cost involved.............you can fine tune and perfect a floor plan like you have (which I reckon is pretty good as a plan), but when push comes to shove it always comes back to budget and costs, which is why we always are encouraging people to utilise design professionals who manage the challenge of designing within budget limits. If you separate budget/costs from the design process (rather than integrate it) more often than not it will leads to disappointment and misalignment of your expectations of what is realistic.