Do You Actually Need an Architect? An Honest Guide

A chartered architect (registered with the Architects Registration Board and a member of RIBA) provides:

• Design — creating the layout, form, and appearance of the extension
• Technical drawings — plans, elevations, sections, and details for planning and building regulations
• Planning applications — preparing and submitting the application
• Building regulations drawings — detailed construction drawings
• Project management — overseeing the build, managing the builder
• Specification writing — describing materials, finishes, and workmanship standards
• Tender process — helping you select a builder through competitive quotes

Not every project needs all of these services. Many architects offer a partial service (design and planning drawings only) for a lower fee.

• Listed buildings. Design quality and sensitivity to the historic fabric matter hugely. Listed building consent applications require a heritage statement and a level of design skill that chartered architects are trained for.
• Conservation areas. Councils scrutinise design quality more closely. A well-designed scheme from an experienced architect is more likely to be approved.
• Complex or bespoke designs. If you want something architecturally distinctive — a contemporary glass extension on a period property, a cantilevered structure — an architect’s design skills are essential.
• Large projects. A two-storey extension, a whole-house renovation, or a project that fundamentally changes the layout benefits from an architect’s design thinking.
• Previously refused applications. An architect with experience in your council area can redesign the scheme to address the refusal reasons.
• When design adds value. If you are extending a high-value property, the quality of the design directly affects the value it adds.

• Straightforward single-storey rear extensions. A 4m rear extension on a semi-detached house built under permitted development does not need an architect’s design input. An architectural technologist or building designer can prepare the drawings for less money.
• Simple loft conversions. A standard rear dormer does not require an architect. Many specialist loft conversion companies include design and drawings in their price.
• Garden offices. Most garden buildings are manufactured products. You do not need an architect — the supplier provides the design.
• Porches and small additions. The design is straightforward enough for a building designer or even a competent builder to handle.
• Like-for-like replacements. Replacing windows, re-roofing, or replacing a boiler do not need an architect.

Architectural technologist (CIAT registered)

An architectural technologist specialises in the technical side of building design — construction details, building regulations compliance, and producing working drawings. They are members of the Chartered Institute of Architectural Technologists (CIAT). For most home extensions, an architectural technologist does everything you need at a lower cost. Typical cost: £800–£2,500 for a straightforward extension (drawings only).

Building designer

A building designer prepares architectural drawings but is not regulated by ARB or CIAT. The quality varies significantly. Typical cost: £500–£1,500 for a straightforward extension. Caution: Because the term “building designer” is not protected, anyone can use it. Check their portfolio and references.

Online design services

Several companies offer architectural design services online at a fixed price. Typical cost: £500–£1,200 for a straightforward extension package. Pros: Affordable, predictable cost, fast turnaround. Cons: No site visit, limited design input, may not understand local planning context.

Specialist companies

Many loft conversion companies and extension builders include design and drawings as part of their package. This can be cost-effective because design, approval, and construction are all managed by one company.

For a straightforward single-storey rear extension, the difference between an architect and an architectural technologist can be £1,000–£3,000 — with no practical difference in the quality of the drawings.

Be aware that “architect” is a protected title in the UK. Only someone registered with the Architects Registration Board (ARB) can legally call themselves an architect. Companies offering “architectural services” may not employ registered architects — they may be staffed by architectural technologists or designers.

This is not necessarily a problem. For most home extensions, you do not need an ARB-registered architect. But if you are paying architect-level fees, check who is actually doing the work.

1. Define what you need. Drawings only? Planning submission? Building regulations? Project management?
2. Get three quotes. Compare like for like — make sure each quote covers the same scope of work.
3. Look at their portfolio. Have they done similar projects to yours? In your area? With your council?
4. Check qualifications. RIBA for architects, CIAT for technologists.
5. Ask about planning success. If you need planning permission, ask how many applications they have submitted to your council and what the success rate is.