A construction dispute often begins long before a defect is discovered or a payment is withheld. It may begin when the parties select AB 04 where ABT 06 would have reflected the intended allocation of responsibility – or the reverse. In the AB 04 vs ABT 06 decision, the central question is straightforward: who is responsible for the design and for ensuring that the agreed function can be achieved?
That question affects pricing, insurance, documentation, change orders, schedules, inspections, and the prospects of resolving a dispute efficiently. For property owners, developers, contractors, and project managers working in Sweden, the choice should be made before procurement documents are finalized, not after work has begun.
AB 04 and ABT 06 are not laws
AB 04 and ABT 06 are widely used Swedish standard contract conditions developed for construction projects. They do not apply automatically. They become binding only when the parties incorporate them into their agreement, normally with project-specific additions and deviations in an administrative specification.
AB 04 is intended for construction and civil engineering contracts where the employer provides the design basis. This is commonly described as a construction contract. ABT 06 is intended for design-build contracts, often called turnkey contracts, where the contractor is responsible for both design and construction.
The labels can be misleading if they are treated as a complete answer. A contract may be called a design-build arrangement while the employer still retains significant design responsibility. Conversely, an AB 04 project may require the contractor to perform limited design work. What matters is the actual contract documents and how responsibility is allocated in them.
AB 04 vs ABT 06: the key difference in responsibility
Under AB 04, the employer typically provides drawings, specifications, and other design documents. The contractor is primarily responsible for carrying out the work professionally and in accordance with those documents. If the employer’s design contains an error, the starting point is that the employer bears the consequences, provided the contractor had no reason to identify and report the error.
The contractor does have a duty to review the provided documents and notify the employer of apparent inconsistencies, errors, or unsuitable solutions. This review duty is significant, but it does not normally convert the contractor into the party responsible for the entire design.
Under ABT 06, the contractor has broader responsibility. The contractor is expected to design and execute the work so that the agreed result and function are achieved. If the project requires a building system to meet a stated capacity, performance, or operational purpose, the contractor generally carries the risk that its chosen design will satisfy that requirement.
This distinction is particularly important when the employer’s procurement documents contain both detailed technical instructions and functional requirements. The more the employer dictates the solution, the more difficult it can become to determine whether a later failure stems from the contractor’s design responsibility or from an employer-prescribed solution.
Functional requirements require careful drafting
ABT 06 is often chosen because the employer wants one party to take responsibility for the final result. That benefit depends on clear functional requirements. Terms such as “high quality,” “energy efficient,” or “suitable for intended use” may create disagreement rather than certainty unless they are connected to measurable standards, operating conditions, capacities, and acceptance criteria.
For example, a requirement that a ventilation system provide an appropriate indoor climate leaves room for argument. A requirement tied to specified airflow, temperature ranges, occupancy levels, noise limits, and measurement methods is much easier to assess. In a design-build project, unclear requirements can result in disputes over whether the contractor failed to deliver the promised function or merely complied with incomplete instructions.
Risk allocation affects price and procurement
A contractor pricing an ABT 06 project must account for a wider range of risks. It may need to investigate site conditions, develop technical solutions, coordinate consultants, verify performance requirements, and bear responsibility for design errors. That usually justifies a higher price than a comparable AB 04 contract.
For an employer, ABT 06 can reduce the need to manage detailed design and coordination. It can also create a clearer single point of responsibility. However, that does not mean the employer can safely provide vague documents or change requirements throughout the project without cost consequences.
AB 04 may be more suitable where the employer has already invested in completed design documents, where architectural or technical control is essential, or where the employer wants to select the precise materials and methods. In that model, the employer has greater control but also retains more responsibility for the adequacy of the design.
Neither form is inherently safer. The appropriate choice depends on the project’s maturity, technical complexity, schedule, and the party best able to evaluate and manage the relevant risks.
Changes, additional work, and documentation
Both AB 04 and ABT 06 contain provisions concerning changes and additional work, commonly referred to as ÄTA work. In practice, disputes often arise because an instruction was given informally, the price was not agreed, or the parties did not document whether the work was actually outside the original scope.
A contractor should promptly clarify whether a requested measure is a change, an addition, or a correction included in the original contract price. The employer should make sure that instructions are issued by an authorized representative and that cost and schedule effects are assessed before the work proceeds whenever possible.
The design responsibility under ABT 06 adds another layer. A contractor cannot characterize necessary work as additional merely because its own design solution proved inadequate. If the work is required to achieve an agreed function, it may fall within the contractor’s original undertaking. On the other hand, a genuine change to the employer’s functional requirements may entitle the contractor to additional compensation and an extension of time.
Contemporaneous documentation is often decisive. Meeting minutes, written notices, revised drawings, site records, and email confirmations can establish what was requested, when the issue became known, and whether the other party objected. In a later dispute, a well-maintained project record is usually more persuasive than recollections formed months afterward.
Delays and defects must be assessed against the right obligation
Delay claims require an analysis of cause, notice, and contractual consequence. Was the delay caused by a change ordered by the employer, defective employer-provided design, late access to the site, an unforeseen circumstance, or the contractor’s own planning? The answer may determine whether the contractor is entitled to more time, compensation, or exposed to delay damages.
The same applies to defects. Under AB 04, the question often is whether the contractor performed in accordance with the employer’s design and accepted professional standards. Under ABT 06, the inquiry may extend to whether the completed work fulfills the promised function, even where the contractor followed its own drawings correctly.
Inspections are therefore critical under both standard forms. The final inspection does not eliminate every potential claim, but it can affect how defects are identified and handled. Parties should prepare carefully, ensure that relevant documentation is available, and address observations with a clear plan for responsibility and correction.
Common mistakes when choosing between AB 04 and ABT 06
Problems frequently arise when the contract form and procurement material point in different directions. An employer may use ABT 06 but provide extensive detailed design without clearly stating who carries the risk for those prescribed elements. Or a contractor may accept AB 04 while undertaking broad design work without pricing or defining that added responsibility.
Another common mistake is relying on general deviations without considering their combined effect. A short amendment can substantially alter liability, time limits, payment rights, or the consequences of design errors. Contract documents should be reviewed as a whole, including the order of precedence between specifications, drawings, tender documents, and later amendments.
It is also wise to avoid copying provisions from a prior project without testing them against the current scope. A clause appropriate for a straightforward renovation may be unsuitable for a technically complex development involving multiple disciplines, operational requirements, or phased completion.
Make the allocation clear before work starts
The best time to resolve uncertainty is during procurement and contract negotiation. Define the scope, identify the design documents that govern, specify performance requirements, and state clearly which party bears responsibility for each critical interface. Where responsibility is shared or divided, that division should be expressed precisely rather than assumed.
For significant projects, early legal review can help identify conflicts between the chosen standard form and the commercial arrangement the parties actually intend. Advantage Advokatbyrå assists clients with construction contract review, negotiations, change-order issues, defect claims, and disputes where the allocation of design and performance responsibility is contested.
A well-chosen contract form will not prevent every construction problem. It can, however, give the parties a practical framework for addressing problems while the project is still moving forward – when a clear written position and timely dialogue can protect both the project and the business relationship.
