How much contingency should I allow on a building budget?

Set aside 10–15% of your total budget. It covers hidden issues, upgrades or changes without stress — in our worked example, a $30k contingency on a $400k renovation absorbed $15k of unexpected structural, electrical and plumbing repairs with room to spare.

How accurate is a builder's estimate?

It depends on the detail you provide. From concept or sketch plans, estimates may vary by ±20–25%; with architectural and engineering plans, ±10–15%; with full specifications (item schedules, finishes, electrical and cabinetry plans), within ±5% — usually enough for a fixed-price contract.

When should I send my plans to a builder?

As soon as you have preliminary drafted designs — before you invest in detailed documentation or engineering. It confirms the design actually aligns with your budget, and only then is it worth engaging an engineer for structural plans.

What kind of projects do you take on?

Renovations, extensions, new builds, decks and pergolas, kitchens and bathrooms, and granny flats — across Newcastle, Lake Macquarie & the Hunter. Most of our work is in existing family homes: opening up a layout, adding a second storey or a rear extension, or rebuilding the outdoor living space.

Where do we start if we're thinking about a project?

With a conversation, and it costs nothing. Bring whatever you've got — full plans, a rough concept, or just an idea and a budget in mind — and we'll walk through what's realistic, what it involves, and what it's likely to cost. Sharing a ballpark budget early means the design gets developed around it, not the other way round.

Are you licensed and insured?

Yes. Delaney Construction Projects Pty Ltd holds NSW builder licence 369751C and is fully insured. ABN 57 649 015 341, GST-registered since March 2021. You can verify the licence on the NSW Fair Trading register.

Fixed-price or cost-plus — which contract is better?

Both have their place. If your plans and selections are mostly finalised — often the case on a new build — a fixed price can work well. For renovations and extensions, where hidden conditions and evolving decisions are common, we prefer cost-plus: you pay the actual cost of materials and labour plus our agreed margin, with a detailed budget before work begins, fortnightly cost updates, and every invoice and receipt available to you. No inflated "just in case" allowances.

What do you need from us to price the job?

To prepare an estimated cost breakdown and an initial budget we only need architectural plans and engineering plans. Approvals (DA, construction certificate, stamped plans) aren't required at that stage but help, because they show the job can legally proceed. For a fixed-price contract you'd also finalise electrical and lighting plans, cabinetry drawings, fixtures and fittings schedules, and finishes selections.

How accurate is a builder's estimate?

It depends on the detail in your plans. Concept or sketch plans: roughly ±20–25%. Architectural and engineering plans: ±10–15%. Full specifications with item schedules and finishes: within about ±5%, which is usually enough for a fixed-price contract. We also recommend setting aside a 10–15% contingency for hidden issues, upgrades or changes.

Who will actually be on site?

Tobin and his own crew. You deal directly with the builder who quoted the job — not a sales rep who hands you over once the contract is signed.

Can we live in the house during a renovation?

Often, yes — it depends on the scope. We'll tell you straight up whether it's workable, and if it is we plan the staging around it so there's always a usable kitchen or bathroom.

Journal

September 2026 · 5 min read · Delaney Construction Projects

What's the best way to plan your budget?

Budgeting is one of the most important parts of any building project. The right process ensures your design ambitions align with your financial comfort zone, and that you have confidence in the numbers from day one.

Renovated kitchen with sage joinery and stone island by Delaney Construction Projects

Step 1: Start with a realistic figure

Begin by setting a ballpark figure for what you're comfortable spending. This doesn't need to be precise but should reflect what you're realistically willing to invest.

Share this figure early with your architect or draftsperson so that your designs are developed with your budget in mind, avoiding over-designing from the start.

Step 2: Send drafted plans to your builder

Once you have preliminary designs, share them with your builder. This step is critical: it ensures the proposed design actually aligns with your budget before you invest further in detailed documentation.

Step 3: Confirm budget alignment, then engage an engineer

If the builder's initial estimated costs are within your proposed budget, the next step is to engage an engineer to prepare structural and engineering plans. These allow for a more accurate costing process and ensure the design is not just beautiful but also buildable.

Step 4: Decide on contract type (fixed-price vs cost-plus)

The right contract depends on the project and how much is already locked in:

Fixed-Price may suit new builds where plans and specifications are highly detailed
Cost-Plus often suits renovations and extensions, where flexibility is important and unknowns are common

Step 5: Allow for contingencies

Every project benefits from a contingency buffer. Setting aside 10–15% of your total budget helps cover hidden issues, upgrades, or changes without stress.

Step 6: Manage costs during construction

How costs are managed on site depends on the contract you chose:

Fixed-Price Contracts – the overall price is agreed before construction, but variations may arise if you request changes or if unforeseen site conditions are uncovered. The key here is to understand how variations are priced and approved so you can make informed decisions quickly without delays
Cost-Plus Contracts – you receive regular budget updates as the project progresses. At Delaney Construction Projects, we provide fortnightly cost reports, access to receipts and invoices, and clear explanations of how selections or changes impact your running total. This transparency helps you stay in control and adjust as needed

How accurate are builder estimates?

The more detail provided, the more confidence you can have in the numbers:

Concept or sketch plans – estimates may vary by ±20–25%
Architectural and engineering plans – estimates narrow to ±10–15%
Full specifications (item schedules, finishes, electrical/cabinetry plans) – estimates can be accurate to within ±5%, which is typically detailed enough for a fixed-price contract

Example: a renovation budget in practice

Imagine you've set a $400k budget for a renovation:

Drafted plans are reviewed by your builder, and they estimate $385k
You move forward with engineering plans and confirm the figure is realistic
You set aside a $30k contingency
During construction, structural deficiencies and issues with existing electrical and plumbing services are found and require $15k of repairs
Thanks to your contingency, the project stays within budget — and you still have room to add upgraded features or finishes if you'd like to

Our approach

At Delaney Construction Projects, we guide clients through every stage of budgeting — from initial ballpark estimates to transparent cost-tracking during construction. The goal is simple: “no surprises, no guesswork — just clarity, control, and confidence in where your money is going.”

Common questions

How much contingency should I allow on a building budget?: Set aside 10–15% of your total budget. It covers hidden issues, upgrades or changes without stress — in our worked example, a $30k contingency on a $400k renovation absorbed $15k of unexpected structural, electrical and plumbing repairs with room to spare.
How accurate is a builder's estimate?: It depends on the detail you provide. From concept or sketch plans, estimates may vary by ±20–25%; with architectural and engineering plans, ±10–15%; with full specifications (item schedules, finishes, electrical and cabinetry plans), within ±5% — usually enough for a fixed-price contract.
When should I send my plans to a builder?: As soon as you have preliminary drafted designs — before you invest in detailed documentation or engineering. It confirms the design actually aligns with your budget, and only then is it worth engaging an engineer for structural plans.