The cheapest time to change your home is before it's drawn. Once the plans are approved and the contract is signed, every change becomes a variation, with a price and a delay attached. This post walks through our new C20 Design Your New Home Checklist: what it is, what it does, when to use it, and what you get out of it.
What it is
C20 is a fillable, 47-page guide with 372 questions across 30 sections. It covers everything that shapes how your home works and what it costs to live in: orientation and sun, energy and comfort, levels and drainage, the slab and frame, windows, lighting and power, wet areas, finishes, storage, outdoor areas and the contract.
Each question comes with a short explanation of why it matters. Instead of Fine, Later and Issue, you mark each one Decided, Ask or N/A, then take every open question to your designer or builder. Key questions, the ones that are costly to change later, are marked so you can deal with them first.
C20 sits early in our series, alongside C1 (Before Buying Land) and C4 (Asking the Right Questions).
What it does
Builders expect you to know what to ask for. Most people building for the first time simply don't. C20 closes that gap:
- It puts the right questions in front of you while the answers are still free to change.
- It gets decisions into writing, in your plans and specification, not in a conversation you'll both remember differently.
- It flags the expensive ones, like slab levels, drainage, orientation and window sizes, so they're settled first.
When to use it
- While your plans are being drawn, before the design is final.
- Before you sign the contract, so the specification matches what you've decided.
- With your designer or builder, section by section. Bring your floor plan, elevations, site plan, electrical layout and specification.
Why use it
Because the problems that cost the most are usually decided early and noticed late:
- Sun and orientation: living areas that bake in summer or never see winter sun.
- Levels and drainage: a slab set too low, or ground that falls towards the house.
- Power and lighting: too few power points, switches in the wrong place, no data where you need it.
- Storage and layout: no linen cupboard, a laundry with nowhere to fold, a garage too short for the car.
- Running costs: insulation, glazing and hot water choices you'll pay for every quarter.
Each of these is a quick conversation at design stage, and an expensive variation, or something you live with, later.
What's in it for you
- A home designed around how you live, not around the standard plan.
- Fewer variations and delays, because decisions are made once and written down.
- Better conversations with your designer and builder. You'll know what a real answer sounds like compared with a reassuring one.
- A clear record of what was agreed, ready to check against the plans and specification before you sign.
What's inside: the 30 sections
| Section | Questions |
|---|---|
| S1Getting started | 10 |
| S2Approvals and timing | 8 |
| S3Land and site | 15 |
| S4Hazards and site risk | 9 |
| S5Neighbours and shade | 17 |
| S6Layout and storage | 12 |
| S7Orientation and sun | 27 |
| S8Energy and comfort | 12 |
| S9Acoustics and sound | 9 |
| S10Levels, drainage and subsidence | 21 |
| S11Slab, footings and floors | 17 |
| S12Structure and frame | 12 |
| S13Roof design | 11 |
| S14Walls, brick and cladding | 11 |
| S15Windows and doors | 12 |
| S16Lighting and electrical layout | 14 |
| S17Plumbing, hot water and tanks | 10 |
| S18Heating, cooling and ventilation | 9 |
| S19Wet areas and waterproofing | 10 |
| S20Tiling | 9 |
| S21Floor coverings | 10 |
| S22Ceilings, linings and glancing light | 9 |
| S23Painting, colour and finish | 10 |
| S24Kitchen, laundry and joinery | 10 |
| S25Indoor air, moisture and materials | 10 |
| S26Garage, outdoors and landscaping | 25 |
| S27Accessibility, safety and security | 10 |
| S28Maintenance and durability | 14 |
| S29Living, running costs and life after handover | 9 |
| S30Contract, certificates and handover | 10 |
| Total | 372 |
Plus a result page to total your Decided, Ask and N/A marks, and list what to take to your designer or builder.
C20 is also in The Complete Set, every checklist we make from C1 to C21.
A few honest caveats
- C20 is a guide, not legal, financial or engineering advice. Requirements differ between states, councils and sites, so confirm details with your designer, builder and engineer.
- Not every question applies to every home. Mark those N/A and move on.
- If an answer matters to you, make sure it ends up in the plans or the specification. A verbal "yes" isn't enough.
Related reading
Checklist for Buying Land: Essential Factors to ConsiderAvoid potential pitfalls and unforeseen expenses by using our comprehensive checklist. From location and zoning to soil conditions and noise concerns, this guide explains the key factors to consider before making your purchase. Make informed choices and secure a land plot that fits your needs.
Questions to Ask When Choosing a BuilderHiring the right builder is essential. In this post we discuss our C4 Asking the Right Questions (Choosing Your Builder) checklist: questions to assess a builder’s experience, quality practices and project management, so you can decide with confidence before signing a contract.
BAL Ratings Explained: Bushfire Attack Levels for New HomesBuilding in bushfire-prone areas? This guide explains BAL levels, what drives your property’s rating, and what changes in design, materials, approvals, and cost—especially windows, roofs, vents, and ember protection—so you can avoid late surprises.
