Structural Engineer vs Architect UK — When Do You Need Each?

One of the most common sources of confusion for UK homeowners embarking on a building project is understanding the difference between an architect and a structural engineer — and knowing which professional they actually need. This guide explains both roles, when you need them, and how combining both under one roof saves money and time.

What Does an Architect Do?

An architect is a design professional who plans, designs, and oversees building projects. Their role includes:

• Understanding your needs and translating them into a building design
• Producing drawings for planning applications and building regulations
• Ensuring designs comply with planning policy and local guidelines
• Coordinating other consultants (structural engineers, M&E, landscape)
• Managing the tender process and appointing contractors
• Overseeing construction quality on site
• Certifying practical completion

In the UK, only someone registered with the Architects Registration Board (ARB) can legally call themselves an “architect.” Many architects are also members of the Royal Institute of British Architects (RIBA).

What Does a Structural Engineer Do?

A structural engineer analyses and designs the structural elements of a building — the parts that carry loads and resist forces. Their role includes:

• Designing structural elements: foundations, beams, columns, floor structures, roof structures
• Calculating loads and ensuring structural safety
• Specifying the size and type of steel beams, concrete, or timber elements
• Preparing structural drawings and calculations for building regulations
• Advising on ground conditions and foundations
• Checking existing structures before modification

Structural engineers are typically members of the Institution of Structural Engineers (IStructE) or the Institution of Civil Engineers (ICE).

Key Differences at a Glance

Architect	Structural Engineer
Focuses on design, function, and aesthetics	Focuses on structural safety and integrity
Leads the design process	Supports the design with technical analysis
Manages planning applications	Prepares structural calculations for building regs
Coordinates the project team	Designs specific structural elements
ARB registered	IStructE or ICE member
Typical cost: 8–12% of build cost or fixed fee	Typical cost: £500–£2,000 for residential

When Do You Need an Architect?

You should engage an architect when:

• You need planning permission and want the best chance of approval
• Your project requires creative design input to maximise space and value
• You’re undertaking a complex project with multiple consultants to coordinate
• You want professional oversight of the contractor during construction
• You’re working on a listed building or in a sensitive location
• You want a complete service from feasibility to handover

When Do You Need a Structural Engineer?

You should engage a structural engineer when:

• You’re removing a load-bearing wall (virtually all projects require this)
• You’re installing a new beam or lintel
• You’re building an extension (for foundation and structure design)
• You need a loft conversion (new floor structure and roof modifications)
• You’re concerned about subsidence, cracking, or structural movement
• You’re converting a garage or outbuilding into habitable space
• Building control requires structural calculations for approval

Do You Need Both?

For most residential extension and conversion projects, the answer is yes — you need both. The architect designs the scheme and handles planning; the structural engineer provides the technical calculations for building regulations.

However, hiring them separately introduces coordination challenges, communication gaps, and additional cost. The most efficient solution is a practice that combines both disciplines — like Crown Architecture & Structural Engineering Ltd.

How Crown Architecture Saves You Time and Money

At Crown Architecture, our team includes both qualified architects and structural engineers. This means:

• One appointment: No need to manage separate professionals
• Integrated drawings: Architectural and structural drawings produced together, avoiding coordination errors
• Faster delivery: Internal coordination is faster than coordinating between separate firms
• Single fixed fee: One invoice covering both services

Typical Project Scenarios

Single Storey Rear Extension

Needs both: architect for planning drawings and design; structural engineer for foundation design, beam calculations, and building regulations package.

Removing a Load-Bearing Wall

Primarily a structural engineer’s job. They will calculate the required beam size and specify the support. An architect may draw up the revised layout for building regulations.

Loft Conversion

Needs both: architect for planning (if required) and layout design; structural engineer for new floor structure, dormer structure, and ridge modifications.

New Build House

Definitely needs both, plus potentially a civil engineer for drainage and groundworks design.

Frequently Asked Questions

Can a structural engineer replace an architect?

Not for design work or planning applications. A structural engineer ensures structural safety; an architect ensures the building works as intended, meets planning requirements, and achieves the best outcome for you. They are complementary, not interchangeable.

Can an architect replace a structural engineer?

Only if they also hold structural engineering qualifications. Some architects have both, but you should always confirm qualifications. Building control will require structural calculations from a suitably qualified engineer.

How much does a structural engineer cost for a house extension?

For a typical residential extension, structural engineering fees range from £600–£1,500. Crown Architecture includes structural engineering within our fixed-fee packages.

Do I need a structural engineer to remove a wall?

Yes — if the wall is load-bearing, you must have a structural engineer specify the beam before removing it. Building control will require this. Attempting to remove a load-bearing wall without a structural assessment is dangerous and illegal.

Contact Crown Architecture

Crown Architecture & Structural Engineering Ltd provides both architectural and structural engineering services for residential and commercial projects across London and the South East. One call, one fee, one team. Contact us on 07443 804841 or info@crownarchitecture.co.uk.