I think the most difficult thing about home extensions is matching the style of your home's original construction. The challenge comes when you don't WANT it to look the same. Then it's a matter of extending, but refining the design to be what you want, but still adapting it to the original style. It's a delicate art, as you can see from this pic. http://www.ahcbuilding.com.au
In an attempt to avoid onerous planning conditions the arrangement of spaces envelop the rear elements of the original workers cottage and partly sit under the original roof, expressed as a lofty higher volume over the family living area.