Early contractor involvement, or ECI, means a builder helps shape the design and the price before the main contract is signed. On a house or renovation it works as two stages: a paid first stage for design input and costing, then a building contract once the price is known.
Be clear on one thing first. ECI is a term from larger projects. There is no separate residential ECI contract. What follows is the small-scale version, using the contracts residential regulators already describe.
Where early contractor involvement comes from
In UK usage, a UK reference site quotes the Institution of Civil Engineers defining it as a non-traditional procurement route where a contractor’s skills are introduced early into a project. On big projects it is usually run as a two-stage tender. The first stage buys the contractor’s involvement in design. The second buys construction.
The trade-offs are the same at any size. The builder can advise on buildability, sequencing and risk while the design can still change. But roles can blur, a price on an unfinished design is never exact, and once one builder is embedded, stage two is rarely competitive.
That definition comes from infrastructure and commercial work. Do not carry its rules over to a house. In Australia, the rules for a house sit in your state’s domestic building laws. If the client wants one builder to design and build under one arrangement, that is closer to design and construct.
The two stages on a house job
Stage one is design and cost work. The builder works with the client and the designer on what can be built, in what order, on this site, for what money. Stage two is the building contract, priced from the finished drawings.
In practice stage one may include a site visit, a feature survey, a soil report, budget advice, early talk with certifiers or council, and a priced scope. See our notes on feature and contour surveys and geotechnical reports.
What the client pays for in stage one
Queensland’s building regulator describes a preliminary agreement as an agreement made before the building contract so the contractor can be paid upfront for initial work such as designs, drawings and specifications, soil tests or contour surveys. That is the residential version of ECI stage one.
The client is paying for work and information, not for a promise to build. They should get something they can keep: drawings, reports, a cost estimate. The same page warns that some preliminary agreements include fees or penalties if the client chooses not to proceed with the building contract after receiving the final price, and says this may be illegal. It advises legal advice before signing any agreement with such charges.
Western Australia’s regulator makes a related point: costs paid to a builder for preparing drawings may not be refundable if the owner does not enter a building contract, and owners should check who will own the drawings. State both clearly on your side too. For what goes in the agreement, see what goes in a preliminary agreement. For what to charge and how, see charging for preliminary work.
What stage two starts with
Stage two starts with a normal building contract, and every state rule for that contract applies as if stage one never happened. That means the thresholds, the required contents, the deposit caps and the insurance. For example, New South Wales requires a written contract for residential work over $5,000, with extra requirements above $20,000, including a cooling-off statement. Victoria requires a written contract for work over $10,000, and its domestic building contract laws change by 1 December 2026. Check your own state.
Price type matters too. Queensland’s regulator calls cost plus contracts particularly dangerous for owners, saying owners have reported final costs 50 to 100 per cent higher than expected, and that home warranty non-completion protection is not available for them. So the aim of stage one is to get to a price firm enough that stage two can be a fixed-price contract. If a number cannot be fixed, list it as a clearly labelled allowance.
Who it suits and who it does not
It suits jobs where the cost is hard to know without design work and site checks: custom homes, extensions on old houses, sloping or awkward blocks, heritage or tight sites. It suits clients who value the builder’s input and are not just collecting three prices.
It does not suit a simple, fully drawn job where the client already has finished drawings and wants a competitive price. It does not suit a client who wants to use your stage-one work to tender to others. It is the same problem from the other side: once a builder is embedded, other builders lose interest. If the client intends to take your drawings and costings to market, a paid stage one is how you are paid for that.
It is also not worth it when the client cannot say yes to the idea of paying for early work. Do not argue. Offer a free rough range, with the caveats, and let them decide.
What to put in writing
- What stage one covers, and what the client receives at the end.
- The price for stage one, when it is due, and whether any of it comes off the build price. State it either way.
- Who owns the drawings and reports, and whether the client can take them to another builder.
- What happens if the client does not proceed, in terms your state allows.
- How stage two is set: a fixed price within a stated time, or a clear way to reach one.
- How long the stage-two price stays open.
Our pre-construction page sets out how we help builders run this early stage.
This is general information only. It is not legal advice. Rules on preliminary agreements and building contracts differ by state, so check with your regulator or a solicitor for your situation before you rely on any of it.
Common questions
What is early contractor involvement?
A way of bringing a builder in before the main contract so they can advise on design, cost and sequence. It usually runs as two stages.
Is there a residential ECI contract in Australia?
Not under that name in the regulator pages we read. The residential equivalent is a preliminary agreement for the early work, followed by a building contract that meets your state’s rules.
Does the client have to use the same builder for stage two?
That depends on what you agree. If they can leave after stage one, say so and price stage one accordingly. If you want first right to price stage two, write that down.
What is a two stage tender?
One stage engages the contractor to help with design. The second stage engages them to build, once the price is agreed.