For property developers building new dwellings who are navigating all the fun stuff that comes with that process, the word "variation" is one that's almost guaranteed to send a chill down their spines.
Understanding what variations are, why they occur, how they are priced, and how to minimise their impact is essential for any developer who wants predictable outcomes and fewer disputes during construction.
So let's dive deep into the exciting world variations!
What Is A Variation?
A variation is any change to the original building contract after it has been signed. This can include changes to:
Variations can be initiated by either the developer or the builder, and they usually involve a change in cost, time, or both.
In development builds, variations are not inherently bad, but poorly managed variations are.
Different Types of Variations
Prime Cost items are allowances for items that have not yet been selected at the time of contract signing. Prime cost items mostly relate to supply only, not installation, and are usually a set amount for the item.
Typical prime cost items include appliances, sanitaryware, tapware, tiles, door hardware, and light fittings. If the developer selects items that cost more than the prime cost allowance, the difference is payable, again usually with a builder’s margin applied.
The danger with Prime Cost items is that allowances are often set at a level that does not reflect the quality expected in the finished development. This can result in a series of “small” variations that collectively add tens or hundreds of thousands of dollars to the build cost. This is a common complaint when using a volume builder.
For developers, the more prime cost items that can be finalised before contract, the better the cost certainty.
Provisional sum items have a much wider application and are used where there is a mixture of items and labour, such as excavation works, pools, or driveways, or an allowance for an item that hasn't been selected yet. It usually applies to work where the scope is known, but the exact cost is uncertain. Often they're listed as a rate, for example $25 per sqm for tiles, rather than a flat amount.
The key risk for developers is that provisional sums are estimates only. If the actual cost of the work exceeds the allowance, the developer must pay the difference, plus the builder’s margin.
From a feasibility perspective, provisional sums reduce price certainty. A contract with a low base price but high provisional sums can appear attractive initially, but may result in significant cost increases during construction.
Unforeseen variations are the worst, because they're... unforeseen? How can you prepare for something you don't know is going to happen? There's a massive boulder lurking beneath the ground that managed to elude the initial soil testing? Ouch!
The good news is that unforeseen variations are what your contingency funds are for.
Why Do Variations Happen?
Let me say straight out that I'm not here to trash builders. Are there some dodgy ones who use variations as a way to try and pull in some more cash? Sure. That's definitely not always the case though.
One of the most common causes of variations in development builds is entering into a building contract before the design documentation is fully resolved. Developers often feel pressure to secure a fixed-price contract quickly to satisfy funding requirements or lock in a builder.
Incomplete documentation can include:
Once construction starts, these “unknowns” turn into variations, often at a premium.
Authority-driven changes are another major source of variations. Councils, building surveyors, fire engineers, and service authorities can introduce additional requirements after construction has commenced. For example:
While these variations are often unavoidable, their cost impact depends heavily on how risk is allocated under the contract.
Site-related issues also play a significant role. These are known as latent conditions, and unless clearly addressed in the contract, they often become a point of contention between developer and builder. Here's a few:
These can all result in costly variations, and can lead to substantial cost increases if the contract does not clearly define who bears the risk.
Developers may choose to initiate variations to improve market appeal, respond to buyer feedback, or enhance resale values. Upgraded finishes, layout changes, additional storage, or façade enhancements can all make commercial sense if the uplift in value exceeds the additional cost.
While these variations are voluntary, they still need to be assessed carefully to ensure the uplift in end value justifies the additional cost and time. In addition to the direct construction cost, developers need to consider builder margins, potential delays, increased holding costs, and any knock-on effects to settlement timelines or funding conditions.
Finally, sometimes variations arise because something was missed or incorrectly priced in the builder’s tender. This is where disputes often occur, particularly if the developer believes the work was already included in the contract sum.
Clear documentation and a well-defined scope of works are critical to avoiding this scenario.
Managing Variations in Property Development Builds
Best practice is for the builder to notify you of the variation in writing, you approve the variation in writing, and then the builder bills you. Sounds great, right? And many builders do operate this way (yay!). There are other things you can do as well to manage variations throughout your project.
Effective variation management starts well before construction begins. High-quality and detailed documentation is one of the most effective ways to reduce variations. The clearer the scope, the fewer assumptions a builder needs to make.
Developers should also take the time to fully understand their building contract or even seek legal advice, particularly clauses relating to variations, provisional sums, prime costs, extensions of time, and builder margins. All variations should be documented, priced, and approved in writing before work proceeds.
When a variation is proposed, ask:
Sometimes the right decision is to accept the variation. Other times, it’s better to hold the line.
Maintaining a realistic contingency allowance is critical. Even well-managed projects experience variations, and a contingency of 5–10 per cent is common depending on project complexity, developer experience and site conditions. Importantly, contingency should be treated as risk protection, not surplus profit.
Variations are not a sign of poor development practice; they are a reality of construction. What separates successful developers from unsuccessful ones is their ability to anticipate variations, understand contractual risk, and make commercially sound decisions when changes arise.
By understanding variations and doing their preparatory work thoroughly, developers can enter construction with clearer expectations, stronger cost control, and a far better chance of delivering projects on time and within budget.
Understanding what variations are, why they occur, how they are priced, and how to minimise their impact is essential for any developer who wants predictable outcomes and fewer disputes during construction.
So let's dive deep into the exciting world variations!
What Is A Variation?
A variation is any change to the original building contract after it has been signed. This can include changes to:
- Design or layout
- Materials or finishes
- Structural elements
- Engineering details
- Compliance requirements
- Scope of works
Variations can be initiated by either the developer or the builder, and they usually involve a change in cost, time, or both.
In development builds, variations are not inherently bad, but poorly managed variations are.
Different Types of Variations
Prime Cost items are allowances for items that have not yet been selected at the time of contract signing. Prime cost items mostly relate to supply only, not installation, and are usually a set amount for the item.
Typical prime cost items include appliances, sanitaryware, tapware, tiles, door hardware, and light fittings. If the developer selects items that cost more than the prime cost allowance, the difference is payable, again usually with a builder’s margin applied.
The danger with Prime Cost items is that allowances are often set at a level that does not reflect the quality expected in the finished development. This can result in a series of “small” variations that collectively add tens or hundreds of thousands of dollars to the build cost. This is a common complaint when using a volume builder.
For developers, the more prime cost items that can be finalised before contract, the better the cost certainty.
Provisional sum items have a much wider application and are used where there is a mixture of items and labour, such as excavation works, pools, or driveways, or an allowance for an item that hasn't been selected yet. It usually applies to work where the scope is known, but the exact cost is uncertain. Often they're listed as a rate, for example $25 per sqm for tiles, rather than a flat amount.
The key risk for developers is that provisional sums are estimates only. If the actual cost of the work exceeds the allowance, the developer must pay the difference, plus the builder’s margin.
From a feasibility perspective, provisional sums reduce price certainty. A contract with a low base price but high provisional sums can appear attractive initially, but may result in significant cost increases during construction.
Unforeseen variations are the worst, because they're... unforeseen? How can you prepare for something you don't know is going to happen? There's a massive boulder lurking beneath the ground that managed to elude the initial soil testing? Ouch!The good news is that unforeseen variations are what your contingency funds are for.
Why Do Variations Happen?
Let me say straight out that I'm not here to trash builders. Are there some dodgy ones who use variations as a way to try and pull in some more cash? Sure. That's definitely not always the case though.
One of the most common causes of variations in development builds is entering into a building contract before the design documentation is fully resolved. Developers often feel pressure to secure a fixed-price contract quickly to satisfy funding requirements or lock in a builder.
Incomplete documentation can include:
- Preliminary engineering
- Incomplete joinery details
- Undefined fixtures and finishes
- Landscaping or external works not fully scoped
- Façade elements
Once construction starts, these “unknowns” turn into variations, often at a premium.
Authority-driven changes are another major source of variations. Councils, building surveyors, fire engineers, and service authorities can introduce additional requirements after construction has commenced. For example:
- Fire separation upgrades
- Stormwater detention changes
- Acoustic treatments
- Energy efficiency measures
- Asset protection conditions
While these variations are often unavoidable, their cost impact depends heavily on how risk is allocated under the contract.
Site-related issues also play a significant role. These are known as latent conditions, and unless clearly addressed in the contract, they often become a point of contention between developer and builder. Here's a few:
- Unexpected rock
- Poor soil conditions
- Contamination
- Undocumented services
These can all result in costly variations, and can lead to substantial cost increases if the contract does not clearly define who bears the risk.Developers may choose to initiate variations to improve market appeal, respond to buyer feedback, or enhance resale values. Upgraded finishes, layout changes, additional storage, or façade enhancements can all make commercial sense if the uplift in value exceeds the additional cost.
While these variations are voluntary, they still need to be assessed carefully to ensure the uplift in end value justifies the additional cost and time. In addition to the direct construction cost, developers need to consider builder margins, potential delays, increased holding costs, and any knock-on effects to settlement timelines or funding conditions.
Finally, sometimes variations arise because something was missed or incorrectly priced in the builder’s tender. This is where disputes often occur, particularly if the developer believes the work was already included in the contract sum.
Clear documentation and a well-defined scope of works are critical to avoiding this scenario.
Managing Variations in Property Development Builds
Best practice is for the builder to notify you of the variation in writing, you approve the variation in writing, and then the builder bills you. Sounds great, right? And many builders do operate this way (yay!). There are other things you can do as well to manage variations throughout your project.
Effective variation management starts well before construction begins. High-quality and detailed documentation is one of the most effective ways to reduce variations. The clearer the scope, the fewer assumptions a builder needs to make.
Developers should also take the time to fully understand their building contract or even seek legal advice, particularly clauses relating to variations, provisional sums, prime costs, extensions of time, and builder margins. All variations should be documented, priced, and approved in writing before work proceeds.
When a variation is proposed, ask:
- Is this genuinely required?
- Does it add value to the end product?
- Can it be deferred or avoided?
- Is the pricing reasonable compared to alternatives?
Sometimes the right decision is to accept the variation. Other times, it’s better to hold the line.
Maintaining a realistic contingency allowance is critical. Even well-managed projects experience variations, and a contingency of 5–10 per cent is common depending on project complexity, developer experience and site conditions. Importantly, contingency should be treated as risk protection, not surplus profit.
Variations are not a sign of poor development practice; they are a reality of construction. What separates successful developers from unsuccessful ones is their ability to anticipate variations, understand contractual risk, and make commercially sound decisions when changes arise.
By understanding variations and doing their preparatory work thoroughly, developers can enter construction with clearer expectations, stronger cost control, and a far better chance of delivering projects on time and within budget.
