form 15 compliance certificate

Why People Are Confused With the Design Phase Process (And How It Actually Works)

Design Phase Process Explained

The Design Phase Process is where most residential projects either move forward smoothly or become delayed and confusing. Homeowners are often unclear about who does what, when structural engineering starts, and why multiple consultants are involved at the same time. This confusion is extremely common, particularly when architectural drawings, structural engineering and certification all begin to overlap.

The purpose of this article is to clearly explain the Design Phase Process so homeowners understand how architects or building designers, structural engineers, certifiers and geotechnical contractors work together. When the Design Phase Process is followed correctly, approvals are faster, engineering is more efficient, and construction begins with fewer surprises.

Why People Get Confused With the Design Phase Process

The main reason people become confused is that several things happen simultaneously, not one after another. Many assume the architect finishes first, then engineering starts, then certification happens later. In reality, these stages overlap.

Typical confusion comes from:

not understanding when structural engineering begins
assuming certification only starts after engineering
uncertainty about who organises the soil test
believing plans can be submitted without structural drawings
unclear communication between consultants

The Design Phase Process works best when clients understand that consultants are working in parallel toward one combined approval package.

Step 1: Engaging the Architect or Building Designer

The Design Phase Process normally starts when the client engages an architect or building designer. Their role is to develop the layout, functionality and appearance of the project.

Typical architectural deliverables include:

floor plans
elevations
sections
site positioning
room layouts and general design intent

These drawings form the base documentation for all other consultants. Structural engineering cannot begin properly until these plans reach a suitable level of detail.

At this stage, homeowners should aim to finalise the overall design direction. Major layout changes after structural engineering begins will usually lead to additional engineering work and extra cost.

Step 2: Architectural Plans Provided to the Structural Engineer

Once the architectural or building designer plans are sufficiently developed, they are provided to the structural engineer. This marks the point where structural design begins.

The structural engineer uses the architectural drawings to determine:

structural load paths
support locations
beam sizing and member selection
slab and footing design
framing requirements
structural stability and bracing

The engineer does not redesign the architecture. Instead, the role is to ensure the proposed structure is safe, compliant and buildable, while maintaining the architectural design intent..

This step is critical within the Design Phase Process because the structural design relies entirely on accurate architectural documentation.

Step 3: Structural Engineering During the Design Phase Process

During this stage, the structural engineer converts architectural intent into structural reality. Structural calculations and design decisions are completed based on span lengths, loading requirements and site constraints.

Typical engineering work includes:

footing and slab design
structural steel or timber design
framing layouts
connection detailing
stability and tie-down systems
compliance with Australian Standards

Good structural design achieves three outcomes:

Structural safety
Practical construction methods
Smooth certification and approval

The objective is not simply compliance but to provide builders with clear and usable documentation.

Step 4: Certification Starts at the Same Time

One of the most misunderstood parts of the Design Phase Process is certification timing.

While structural engineering is being completed, the architect or building designer should already provide the architectural plans to the certifier. This allows certification assessment to begin early.

The certifier will start reviewing:

building compliance requirements
planning rules
setbacks and siting
regulatory matters

However, certification cannot be completed without structural drawings. The certifier will require both architectural and structural documentation before final lodgement with council or approval authority.

Starting certification early reduces delays later in the process.

Step 5: Soil Test Requirement

A soil test is a mandatory part of most residential projects within the Design Phase Process. The soil conditions directly affect foundation and footing design.

The structural engineer will advise the client that a soil test is required and will normally organise this through an external geotechnical contractor.

The soil report provides information such as:

soil classification
founding recommendations
soil reactivity
bearing capacity
groundwater observations

The structural engineer then uses this report to finalise slab and footing design. Without this information, structural foundations cannot be properly engineered.

Organising the soil test early prevents delays and avoids redesign later.

Step 6: Form 15 Issued During the Design Phase Process

As part of the Design Phase Process, once the structural engineering design is completed, the structural engineer prepares a Form 15 – Compliance Certificate for Design. This document confirms that the structural design complies with relevant Australian Standards and engineering requirements.

The Form 15 is issued during the design phase and is provided to the certifier together with the structural engineering plans. The certifier requires this documentation as part of the approval package before the project can proceed toward construction. Providing the Form 15 at this stage helps streamline certification and reduces delays caused by missing compliance documents.

Step 7: Coordination Between Consultants

The Design Phase Process is not linear. Consultants must coordinate together while the design develops.

Typical coordination includes:

architect adjusting layouts based on structural requirements
structural engineer confirming support positions
certifier reviewing compliance during design development
soil report informing foundation design

When coordination is strong, the project progresses efficiently. When coordination is poor, redesign and delays are common.

Step 8: Structural Plans Are Issued

Once the structural design is completed and soil data incorporated, the structural engineer issues structural plans.

These typically include:

slab and footing details
framing layouts
beam schedules
bracing and tie-down details
structural notes and specifications

These structural drawings are then supplied to the architect or building designer and to the certifier.

The Design Phase Process depends on both sets of drawings working together as one package.

Step 9: Lodgement With Council or Certifier

The final step of the Design Phase Process is submitting the complete documentation package.

This usually includes:

architectural drawings
structural engineering plans
Form 15 compliance certificate
soil report
compliance documents

When the Design Phase Process is managed correctly, the certifier can assess everything together, reducing requests for further information and speeding up approvals.

Why the Design Phase Process Matters

The design phase is where most construction problems are either prevented or created. Proper engineering and coordination at this stage delivers:

faster certification outcomes
fewer construction variations
clearer builder pricing
reduced structural risk
smoother project progression

The Design Phase Process is not just paperwork. It is the foundation of a successful build.

Conclusion

People are often confused by the Design Phase Process because several consultants work simultaneously rather than sequentially. Understanding how the architect or building designer, structural engineer, certifier and geotechnical contractor interact removes much of this confusion.

The architectural plans provide the foundation, the structural engineer ensures the design works structurally, the soil test confirms foundation requirements, and the Form 15 is issued to the certifier as part of the compliance documentation. When these steps are coordinated properly, the entire project becomes smoother, faster and more predictable.

If you already have architectural or building designer plans, the next step in the Design Phase Process is engaging structural engineering so the complete documentation package can be prepared for certification and council lodgement.