Chartered Structural Engineer in Staines & Surrey
Get Expert Structural Advice Today
Affordable Expertise
Chartered structural calculations and clear engineering drawings at fair, competitive rates.
Trusted Local Expert
Jonathan Darnell Engineering Ltd delivers safe, regulation-ready designs backed by over 40 years of structural engineering experience in Surrey.
Regulation-Ready
All work meets local Building Regulations and planning requirements across Staines-upon-Thames and surrounding areas.
Client-Focused
We provide tailored structural solutions and clear, no-jargon advice throughout your project.
About us
Structural Engineering That Supports Your Vision
With over 40 years of experience in structural design and analysis, Jonathan Darnell provides expert solutions for home extensions, loft conversions, structural surveys, and more. As a chartered engineer, he ensures every calculation and drawing is accurate, compliant, and tailored to your project goals.
- Structural Calculations
- House Extension Engineering
- Loft Conversion Support
- Foundation & Retaining Wall Design
- Surveys and Structural Reports
Our Services
Professional Structural Engineering in Surrey
Structural Calculations
Precise calculations for beams, walls, and frames — essential for Building Control and construction safety.
House Extension Design
Engineering plans for side, rear, and two-storey extensions. We ensure your design is safe, buildable, and regulation-compliant.
Loft Conversion Support
RSJ sizing, roof truss assessment, and full support designs for dormer, Velux, or hip-to-gable conversions.
Structural Surveys & Reports
Pre-purchase inspections, crack assessments, subsidence checks and more — with clear written reports.
Why Us
Our Commitment to Engineering Excellence
Chartered Expertise
Jonathan Darnell is a fully chartered structural engineer (MIStructE), offering trusted support across Surrey.
Tailored, Compliant Designs
Every report and calculation is aligned to your build’s needs and local Building Regulations.
Fast Turnaround
We typically deliver calculations or surveys within 3–7 working days. Urgent services available.
Our Projects
Our Projects
Loft Conversion Engineering for Semi-Detached Home in Staines
Ready to Start Your Project?
Let’s get your structural plans in motion. Contact Jonathan Darnell today to book a free consultation or request a quote.
Frequently Asked Questions.
Yes — any extension involving structural changes, beams, or wall removals needs proper calculations for compliance and safety.
Absolutely. We provide full calculations and layout advice for steel beam sizing and placement.
A structural survey includes an on-site inspection, assessment of defects (cracks, movement), and a clear written report.
If the property has visible cracks, subsidence, or structural concerns, yes. We provide reports suitable for mortgage and insurance.
Pricing depends on the scope of work. Contact us for a free quote — our rates are fair and transparent.
Yes. We design safe, effective retaining structures and foundation systems tailored to your soil conditions and build.
Typically 3–7 working days. Faster service may be available depending on workload and project urgency.
Yes — we serve all areas within 10 miles of Staines-upon-Thames, including Ashford, Shepperton, Sunbury, Egham, and more.
Yes — we design structural layouts for lofts, including ridge beams, joists, and dormer support.
Yes — you’ll receive clear advice directly from Jonathan, including site visits, consultations, and reports.
Areas We Cover
Jonathan Darnell Engineering is based in Staines-upon-Thames and proudly provides structural engineering services throughout the surrounding areas.
Chertsey, Chertsey Meads, Thorpe, Egham Hythe, Charlton, Ashford, Birch Green, Ashford Common, Addlestone, Weybridge