Jobs in Castle Cary

Senior Mechanical Design Engineer

Central London | Hybrid | 3 days from home, 2 days in the office

Up to £80,000 + travel

If you are tired of being brought in to review someone else’s design after the key decisions have already been made, this is your chance to take proper ownership.

You are capable of more than checking drawings, answering technical queries and trying to rescue coordination problems late in the programme. You want to lead the mechanical design properly. You want to take a brief, assess the existing services, develop the solution, size the plant, produce the calculations, support procurement and stay close enough to delivery to make sure what gets built still reflects the engineering intent.

This opportunity sits with a design and build building services contractor operating across design, mechanical and electrical delivery, project management, maintenance and public health. The business has a strong presence in office fit out, alongside residential and hospitality, and has an established track record delivering Cat A and Cat B office refurbishment projects and full-service packages up to £1.5m.

For this hire, the focus is firmly on commercial office fit out in Central London. You will take responsibility for the full mechanical design on Cat A and Cat B schemes up to £1.5m, producing practical, buildable solutions that work technically, commercially and on programme.

This is not a role where you sit in the background while someone else drives the job. You will be the engineer shaping the design from the front.

What you’ll be doing

Taking full ownership of mechanical design across commercial Cat A and Cat B fit out projects from early survey and concept through to construction support and handover.

Surveying existing services, identifying constraints, assessing opportunities for reuse or modification, and turning that information into workable design strategy.

Producing mechanical calculations, equipment selections, design intent documents, specifications, schedules and technical submissions with clear, buildable direction.

Designing typical office fit out systems including ventilation, comfort cooling, heating and associated distribution, with proper consideration for access, maintenance, noise, coordination and installability.

Working closely with project managers, site teams, suppliers and subcontractors so the design stays aligned with programme, procurement and site realities.

Supporting value engineering, responding to RFIs, reviewing technical submissions and helping resolve live design issues without losing control of quality or compliance.

Contributing to design standards, QA and general improvement across the function as the business continues to strengthen its in-house design capability.

What you’ll need

A solid background in mechanical building services design, ideally within a contractor-led design and build environment or fast-track commercial office fit out.

Proven experience delivering Cat A and Cat B fit out designs, not just isolated elements or consultant-side packages removed from delivery.

Confidence producing full mechanical designs, calculations and selections rather than simply reviewing or coordinating the work of others.

A practical understanding of buildability, sequencing, site constraints and the commercial pressures that come with live fit out projects.

The ability to manage multiple schemes at once, prioritise properly and communicate clearly with both technical and non-technical stakeholders.

A relevant mechanical or building services qualification would be useful, but the real priority is whether you can lead the work credibly and get designs delivered.

Experience with the usual design tools and calculations software used in building services, including AutoCAD and recognised calculation packages, will be advantageous.

Why this role stands out

You will be trusted to do the full job, not just a narrow part of it.

You will work in a business where design is closely tied to delivery, so your decisions have a direct impact on project success.

You will be involved in fast-paced Central London commercial fit out work where responsiveness, clarity and practical engineering judgement genuinely matter.

You will have the flexibility of hybrid working with 3 days at home and 2 in the office, while still staying closely connected to projects and the wider team.

You will be joining a contractor with an integrated service offer and a collaborative, client-facing approach, built around supporting projects from early ideas through to handover and beyond.

Apply

If you are a senior mechanical design engineer who wants real ownership, proper variety and the chance to shape full Cat A and Cat B office fit out designs in a delivery-focused environment, apply now