A structural engineer is essential for any project that affects the load-bearing structure of your home — whether you’re removing a wall, adding an extension, converting a loft, or underpinning foundations. Yet many homeowners are unclear about what structural engineers actually cost. This guide sets out typical structural engineer fees in the UK for 2025, what each type of work involves, and how to budget accurately.

Typical Structural Engineer Costs by Project Type (2025)

Project Type	Typical Fee Range
Wall removal / RSJ beam calculations	£300 – £700
Single-storey extension (structural calcs)	£500 – £1,200
Double-storey extension (structural calcs)	£800 – £2,000
Loft conversion structural calculations	£600 – £1,500
Basement conversion structural design	£2,000 – £8,000
Foundation investigation / underpinning	£1,500 – £5,000
Structural survey / report on a property	£300 – £1,000
Steel frame design (commercial)	£3,000 – £15,000+
Site visit + verbal advice	£150 – £400

What Does a Structural Engineer Do?

Structural engineers design and assess load-bearing structures to ensure they are safe. On domestic projects, their work typically includes:

• Structural calculations: Mathematical analysis proving that beams, columns, foundations, and slabs can safely carry the loads imposed on them
• Connection details: Drawings showing exactly how structural elements connect — how a steel beam bears on padstones, how a column transfers load to the foundation
• Specification: Specifying the correct steel section size, reinforcement quantities, or timber grade
• Site visits: Visiting site to inspect existing structure, check construction progress, or assess a problem
• Structural reports: Written assessments of a building’s structural condition — often commissioned during property purchase

When Do You Need a Structural Engineer?

You must involve a structural engineer in any project that affects the structural integrity of the building. Common domestic triggers include:

• Removing a load-bearing wall: Requires beam design, padstone specification, and post/column design
• Building an extension: Requires foundation design, beam calculations for openings, and structural connections
• Loft conversion: Requires design of new floor structure, ridge beam (if needed), and dormer frame
• Basement conversion: Requires complex retaining wall and underpinning design
• Adding a floor: Requires assessment of whether existing structure can carry additional load
• Cracks in walls: Structural engineer can assess cause and recommend remediation
• Property purchase: If a surveyor flags concerns, a structural engineer can investigate further

How Structural Engineer Fees Are Calculated

Structural engineer fees are most commonly based on one of:

Fixed Fee

Most common for clearly defined domestic work — beam calculations, extension structural design, loft conversions. The engineer quotes a fixed price for defined deliverables. This gives you cost certainty.

Percentage of Build Cost

Used on larger projects — typically 1–3% of construction value for the structural engineering component. On a £200,000 extension, structural fees might be £3,000–£6,000.

Hourly Rate

Chartered structural engineers typically charge £100–£200 per hour. Site visits are usually charged at a day rate of £600–£1,200 plus travel. Hourly rates apply for consultancy, investigations, and work where scope is uncertain.

Structural Engineer vs Architect: Who Does What?

A common point of confusion for homeowners is the division of responsibility between architects and structural engineers.

The architect handles the design — what the building looks like, how spaces connect, planning applications, building regulations drawings, and project specification. The structural engineer handles the structural engineering — the calculations that prove the structure is safe.

On most domestic projects the two work in parallel: the architect produces the design and the structural engineer provides the structural calculations and details that feed into the building regulations submission.

At Crown Architecture & Structural Engineering, we provide both services in-house — which eliminates the coordination overhead and typically reduces overall professional fees compared to engaging separate firms.

RSJ Beam Costs: Structural Engineer Fees Explained

Removing a structural wall is the most common domestic structural engineering commission. The process is:

• Structural engineer visits site and assesses the wall and the loads it carries
• Calculates the span and required beam size (typically a Universal Beam — UB — section, colloquially called an RSJ)
• Specifies the padstones at each end and any intermediate posts or columns required
• Produces a structural calculation pack and connection details
• These are submitted with the building regulations application

Structural engineer fees for a wall removal are typically £300–£700. The steel beam itself costs £200–£600 for the section alone; fabrication, delivery, and installation labour typically add a further £800–£2,500 depending on size and access.

Tips for Getting Value from Your Structural Engineer

• Engage early: Structural engineers can identify constraints and opportunities at design stage before costly changes are needed
• Provide good information: Accurate floor plans, photos, and building age help engineers quote accurately and avoid site visit costs
• Get at least two quotes: Fees vary significantly between firms
• Check qualifications: Look for MIStructE or CEng MICE — Chartered members of the Institution of Structural Engineers or the Institution of Civil Engineers
• Combined services save money: Using a practice offering both architectural and structural engineering services avoids duplication and reduces coordination costs

Frequently Asked Questions

How much does a structural engineer cost for a wall removal?

Typically £300–£700 for calculations, drawings, and building regulations support on a single wall removal. Larger or more complex structural works cost more.

Do I need a structural engineer for a single-storey extension?

Yes — any extension that involves structural elements (opening up the existing rear wall, new foundations, spanning openings) requires structural engineer input for building regulations approval. Typical fee: £500–£1,200.

Can an architect do structural calculations?

Standard architects are not qualified to produce structural calculations. You need a chartered structural engineer for this. However, some practices (like Crown Architecture) have structural engineers in-house and can provide both services.

How long does it take to get structural calculations done?

For a domestic wall removal or extension, typically 1–2 weeks from information receipt. More complex projects (basement, underpinning) may take 4–8 weeks.

Do I need a structural engineer for a loft conversion?

Yes — all loft conversions require structural calculations for building regulations. The engineer will design the new floor structure, any steel ridge beam, and dormer framing. Typical fee: £600–£1,500.

What qualifications should a structural engineer have?

Look for MIStructE (Member of the Institution of Structural Engineers) or CEng MICE (Chartered Civil Engineer). These indicate a rigorous professional qualification and ongoing CPD obligation.

Does Crown Architecture provide structural engineering services?

Yes — Crown Architecture & Structural Engineering provides in-house structural engineering across all domestic project types including extensions, loft conversions, basement conversions, and wall removals. Call us on 07443 804841 to discuss your project.