Just like birth, death and taxes, renovation surprises are guaranteed. I think Micheal Bell's suggestion to add a contingency is a good one. Also finalising your design before looking for your builder will save on mid project variations. For those interested in estimating the cost of their renovation before going too far into their plans, try this renovation and extension cost calculator. Good luck. richard@makeovergroup (Melbourne)

you probably need a crowd of tradesmen to do all the work (carpenter, kitchen cabinet maker, plumber, electrican. painter, tiler, flooring installer etc) and you can have a builder take control and organise all the workers but the actual design can be done by you or an architect, building designer or kitchen cabinet makers might be able to help but, it depends on what needs doing...why not post some photos and a plan or a rough sketch of the existing rooms (including measurements, position of windows and doors and names of adjoining rooms) with a list of what you like and don't like and invite HOUZZERS to make specific suggestions so that when you need to contact the professionals you have a better idea of what you need

Excellent advice

$300k would be the building budget only and will often not include the architect or other professional service fees like surveyors, engineers and certifiers. The biggest point to remember, is the reason behind engagement of an architect. Are you after a great lifestyle outcome in your home. Are you are detailed person wanting to ensure there is a place for everything in your home. Does your site offer something where you can gain by tremendiously. Do you want your own ideas challenged. The fees set by different architects are yes based around scope of service but also based around their skills and so not all architects do charge the same rates. My own service is for the building architecture, interior design and landscape design, you might say what does that have to do with my lounge room extension and in your case there maybe only interior scope or your external spaces maybe also impacted. My services also includes external real costing work from a cost planner, so you'll know how much your project will be very soon along he steps the delivery process. My service includes project management and my services covers off on a huge range of sustainable and passive design principles which are applied to my clients projects for best outcome. This is why architects fees can vary between providers. It is your lifestyle outcome that is at stake, Once you have spent the money you need to live with it or sell so ensure you factor in the gain in your assessment of fees . Be careful even though some architects have alot of positive reviews this does not mean their design ideas and direction are going to be best for you. Just agreeing with a clients thoughts is not helpful to a client. I charge on a combination of square metre and hourly service and percentage only on request by my clients. $3000 per sqm mention above is mid standard not high spec finish . But standard is subjective as well so this must be worked through with your architect.