Apply for an informal government information public access request through Central Coast Council. Under other documents request any previous plans, reports and DAs submitted on the site. This may give you the original plans and does not cost you anything.
Contact council to get them to give you a call back to discuss what you can do on your property. Use the council form for a call back from their town planners.
If you are prone to flooding you will need to get a flood information certificate. If you are bushfire prone, you will need to get a bushfire report.
A survey shows where your boundaries are, the level of everything, and where your existing building is located on the site. Council usually requires this with the DA. It will also show existing services so you do not plan to build over a sewer main, which can be expensive.
If you are not building on top of existing foundations you may need a Geotech to enable the structural engineer to design footings.
These will be for Development Approval and will include everything required on the DA Council Checklist. This generally includes plans, elevations, sections, shadow diagrams and a notification plan. The level of material detail is relatively simple — council mainly want to know what external materials will be used.
Send the Architectural Set to the stormwater engineer and they will provide stormwater drawings that look at the flow of water on the site and design the stormwater system so your house and garage stay dry.
BASIX consultants make sure there is enough insulation, windows are thick enough and there is enough rainwater storage to create a sustainable dwelling. BASIX is required by the NSW government for all additions over $50,000.
Council may request other consultants depending on the project and zoning — for example an arborist report if you are removing trees, or a bushfire report if you are in a bushfire zone.
After council approves your DA they will provide conditions of consent. Go through these to understand what you need to provide. Common conditions for additions include providing a concrete driveway and a pedestrian path in front of the house — your structural engineer or a separate civil engineer will draw these up.
Send the updated Architectural drawings to a structural engineer and get them to design the structure.
Provide a finer level of detail in the Architectural drawings, including wall types and concrete setout plans.
Engage either council or a private certifier to approve the Construction Certificate.
Pick everything from tiles to paint. This means the builder can price it accurately and you will not get stuck with a builder's margin.
Get your architect to do detailed design drawings of everything that is not a typical detail, and all wet areas. Anything you want to be brilliant — get drawn up. Standard details can be left out.
Look carefully at what each builder is including and excluding in their quote.