Shea CullenNSW Registered Architect 9748 · Updated 10 July 2026Iron out every one of these changes before you sign anything, because your leverage is at its peak right until you sign and it collapses the moment you do. Beforehand the salesperson is motivated to accommodate you. Afterwards the same changes are treated as variations, which can mean a charge of around a thousand dollars each, or a flat refusal because the plan is locked.
Most of these changes make the home cheaper to run, more comfortable and more accessible, and they save you from expensive mistakes. Some cost a little more up front, some save you money. If you cannot do all of them, start at the top of the list, because those have the biggest impact. Then take the checklist below into the showroom with you.
Do not under any circumstances accept 'retaining wall by homeowner'. Retaining walls are very expensive to design and build. Instead spend a bit more time with the drafters designing the levels to have equal cut and fill, get the builders to use edge beams on the foundations of the walls themselves or have small retaining walls under 600mm that you can get landscapers to do without an engineer. Check how steep your block is before you sign, because slope is what turns this into a five figure line item.
This will mean that you get sun in winter and keep it out in summer. The sun travels at a higher angle in summer and a lower angle in winter which you can take advantage of by having this with the right overhangs. Here is a guide to selecting north facing sites for further information.
Ideally you really want most of your windows to be facing north, with the right overhang to block summer sunlight and allow winter sunlight in. East windows are nice to have as well, you really want to minimise west windows and have vertical shades to block the sun in summer. Make your windows to the south small, still have them for cross ventilation though. The passive solar design principles explain the overhang depths that make this work. We really recommend getting a NatHERS assessment done before proceeding with your builder, have a talk to the consultant and see what changes they recommend to windows and doors. It will make a big difference in both how comfortable you are and how much energy you use each year.
Cross ventilation generally only works for distances less than 6m so make sure you have windows across from each other or on a corner within 6m of each other. Windows in the same wall will not help with cross ventilation, the windows need to be at an angle of 90 degrees or 180 degrees. Many project home builders will only have one window on a room even it is a corner room, add another to the other wall where you can. Natural ventilation on the Central Coast covers how to lay this out.
Make sure that the bathrooms are set down in the slab or first floor structure so that after the tile is laid there is no step up, make it level with the floor in the adjacent room. This is important because: if the bathroom overflows you don't want it to overflow into other areas no step means more accessible for older people and less accidents for you robot vacuums can clean them without getting ramps The setdown is decided at the pour, so it has to be right in the contract drawings. What to check before waterproofing is covered is the rest of that story.
This will add expense, you will feel so much better living in these taller spaces though and it means that you can add ceiling fans and really have room to breathe. We experience space all around us, not just width but height as well. If you can make your ceiling heights 2700mm in the living areas, 3000mm is even better if you can afford it. Keep your bedrooms and bathrooms at 2400mm to minimise costs and keep them cosy and easy to heat and cool.
Gas is an ongoing expense, there is a lot of evidence that induction is better for cooking and even that gas causes asthma in kids. Get rid of gas, if you don't get rid of it before signing then it is extremely hard to get rid of so make it a dealbreaker.
Most project home builders provide a tiny amount of solar panels that has no chance of providing enough electricity for you and your family. Up them to at least a 10kW system with an inverter that will still produce electricity even if one panel is in shade. My efficient electric home covers the rest of the running cost decisions.
Timber frames are better for insulation and they also store carbon in the home, reducing the carbon emissions of the build. Steel frames carry heat straight through the wall, which is thermal bridging.
Change your windows to double glazed, have thermally broken aluminium, UVPC or timber window frames. Is double glazing worth it on the Central Coast runs the numbers for our climate. Use awning or casement windows that have a better seal so that you lose less air to convection. Get honeycomb blinds to add insulation to the windows.
Fill your envelope walls around the building with insulation, for the internal walls inside the building envelope, fill them with adobe. This adds thermal mass to the building so that the walls absorb the heat or cool and reflect it back. It acts as a giant battery for your heating and cooling in the building.
Make the R-Value of your walls as high as you can while keeping it viable, R4.5 insulation is now available at affordable prices, see if you can upgrade your package
Reduce waterproofing issues and the thermal load on your building by having at least a 450mm eave, if you can afford go with a 600mm eave, particularly on the North where it will make a big difference how much sun will hit your building. It will dramatically increase the longevity of your windows.
If you have a two storey design, try and make the footprint for both levels the same so there is only one roof, rather than little roofs on the ground floor. This means that there will be less waterproofing issues
Mostly the room sizes in project homes can be a little small, here are some recommended minimum room sizes: Main Bedroom: 3.5x3.6m Other bedrooms: 3.2x3.2m Living: 4x4m Dining: 3.2x3.2m
Condenser dryers are extremely heavy and can only be installed on the ground, make sure the plans do not show a hanging dryer
Most Project Home Builders will only include one tap, make sure you have a tap: at the front at the back on any balconies
Because a lot of project home work is done by apprentices, it is a good idea to locate the GPOs (powerpoints) on internal walls that do not touch the external side of the building. This is because the insulation around them will be more sketchy, so keep them away from those exterior walls.
LED lighting will save you money and lighting with a colour range as close to the sun as possible will help with your eyesight and help stave off depression.
For a finish that is low maintenance, waterproof and works well, bricks are a beautiful material that can last hundreds of years.
Many builders will pay $10/ week they are late building. Make sure there is a significant consequence if they don't finish your project in time, for example how much rent you are paying at least. Questions to ask before signing a building contract covers the rest of the clauses worth arguing about.
Signing with a project home builder is one moment in a longer journey. My guide to everything to sort out before you build on the Central Coast walks through the whole sequence. Before you sign anything, work through the questions to ask before signing a building contract in NSW and check the allowances against my explainer on provisional sums and prime cost items, because low allowances are how a fixed price quietly stops being fixed. And if you are still weighing up which path to take, here is the honest comparison of a project home builder versus an architect.