Vy, I use the Houzz iPad app which has the ability to create your ideal room with measurements, images of the existing rooms that are customisable etc. It might help your situation if you didn't want to hire a designer to do the leg work for you.

sorry about the drawing, but I quickly just sketched over your plans. I tried to keep the basic design you had just to save on re drawing over, but I would suggest the following as there was a lot of wasted space before. Also keep in mind that you are able to flip the house over (mirror image) if it will be too hot for the bedrooms to be on that side. Following the above drawing I would get rid of all the small hallways and extra doors you have, I would put the activity room directly on the Bed 1 wall and have built in bookshelves around the two walls, this will turn it into a study which will be a better choice for resell value. I would also put a skylight in that room as there are no windows. Entry to Bed 1 will be via the corridor which links all bedrooms, it still gives you dbl doors into the master, WIR and your ensuite. Your ensuite I would move the shower to the end and put floor to ceiling glass and turn it into a dbl shower one side can have dbl vanity and the other the WC and you would also have enough room to install a cupboard which could be a nice decorative on with glass on the top half where you could keep your towels and door on bottom to hide things. I would move Bed 4 in line with the other bedrooms, I did not move the main bathroom but you could move int and have it in the middle between two bedrooms. The main bathroom I would do a wet room which incorporates a bath and the shower behind again floor to ceiling glass. You would still have room for dbl vanity and toilet. By moving the activity room in line with the entry way, it will give you room in the bedroom hallway to incorporate a linen cupboard. By moving the drop zone and putting the PDR room door at that end it allows you to have a bigger laundry. therefore, behind the laundry door you could have overhead cupboards as well as undercounter cupboards for extra storage. Drop zones end up becoming messy and with yours right in the entry way, whenever you had guest your mess will be out in the open. By moving all this around it opens up the main hub of the house; it gives you enough room to extend the kitchen bench a little further down, I would put a large square island in the middle it allows for better flow around the kitchen and it also gives you extra seating, especially for quick breaky with the kids in the morning before running out the door to do school drop offs and work. It also gives you extra cupboard space as you are able to have doors put right around underneath for extra cupboards. Your dining area now has grown and leaves you with extra space along the the new study wall that you can have as a kids zone. Firstly, being little you will want to keep an eye on them secondly as they grow they want their own bedrooms. Your family living area is still the same; I would also wrap the pergola around to the end of the house which enables you to build an outdoor kitchen/bbq area with a table for entertaining and on the other end you could have comfy couches to lounge in when outdoors, have your morning coffee and watch the kids play in the backyard. Hope this helps Good Luck

Ikea have an online kitchen designer that works with their modular system. It is quite powerful but you are limited to their module sizes - but they do have lots of modules available. Best of luck Dr Retro of Dr Retro House Calls

Thanks for all your responses. The garage as marked on the plan is incorrect - this is actually a carport and is allowable under Council setbacks. Standard side boundary setbacks requirement is 1.5m, but a relaxation can be sought on this. Thanks for your comments re going up Siriuskey - whether or not to go up is something we have grappled with. I agree that this would probably take best advantage of the block, but it is not how we want to live in this home. Thanks for your thoughts oklouise - there are several elements of your plan that are very appealing - the laundry and powder work really well and the adjustment to the kitchen to have a servery to the kitchen is great. Paul's thoughts about moving the entry to the side of the house with more direct access to the open plan living is are a bit of an eye opener. One of the advantages of this and more of a pavilion style extensions is that an external window could be retained to the proposed music room, allowing it to stay as a bedroom. If it was possible to keep 4 bedrooms in the existing house, the size of the extension could be reduced.