consider painted smooth cement sheet (looks like traditional fibro) with a cover strip over joins or can be rendered and painted

I agree with Oklouise. Also look at the website of Michael Bell architect who posts here sometimes, he has posted some stunning extensions to historic homes including a 2 storey one that sticks in my memory

The look of painted brick might also suit. The finish on the front of your house may be a factor to consider too.

Definiately try to tie in the material on the ground floor exterior to the existing structure somehow, then the upper story with its lighter cladding material will not look out of place. Look around your local area for similar aged properties and have a snoop at materials they have used or that might be original cladding options.

have you got a photo of the front?

Front of the house.

You have a beautiful home Richard, definitely worth taking the time to perfect your design.

I like MOST of the look in the concept drawing , including the weatherboard look and the colour . Like Paul Di Stefano though , something about those 4 upstairs windows doesn't look balanced ,

But then you through a massive curve ball with the front shot -- what parts are you going to retain ? I realise you can't see the front and back at the same time , BUT personally I still think you need similar design elements .

I like the eve and bay window and its own little roof -- imagine how much better your 'rear' drawing would look with a double width version of that in place of the middle two upstairs windows , and then the 'period' lights , and then the outer 2 windows moved out towards the corners !

The upstairs in wetherboard ( or even fake weatherboard ) looks balanced and period -- most of the downstairs is doors and windows , but imagine the rest in the same brick as the front of your house ( or a very close match ) -- breaks the look , but adds a lot of cohesion with the front view .

That would be the lines I would be thinking along , rather than fairly differing styles front and rear ( assuming , of course , that you aren't going to sunstantially alter the front view except for the added roofline ) .

I don't know what floor plans are envisaged for the upstairs extension but to me the proposed shutters look out of place when compared with the downstairs photo that you have provided. The width of the windows appear too narrow and I feel would benefit from being more in scale with what is going on downstairs.

Personally, I would take the opportunity to make a break from the Federation style of the downstairs and make the most of the opportunity that you have, to add some clean modern lines along the lines suggested by Paul Di Stefano Design .

Your renovation is not about what your house has been in the past, or about what the neighbours styles of houses are. It's about what works best for your lifestyle and how that aesthetic can best be tied into the house you have. A Federation house doesn't have to have a Federation Style extension to look good.

If you are west-facing, then your upstairs as-designed is going to get all the sun in the odd windows. Have you considered starting with reducing heat load by verandahs, overhangs, louvres, etc then building a design around that? I am not sure building more west-facing rooms would be great use of your money. What about a different layout completely that focuses on living sustainably with comfort? You could even get a lovely shaded court yard through great design.