How it works
- A free, no-obligation quote. Tell us about the project and you receive an itemised price, with design options where there is a choice.
- Site survey and concept meeting. The engineer visits, takes measurements and plans the structure with you and your architect.
- Your structural package. Drawings and calculations ready for Building Control, designed for strength, safety and cost.
- Support during the build. We stay available for your contractor's questions, revisions and site checks.
Extensions
Rear, side-return and wraparound extensions usually involve opening up the back of the house, which means a steel beam, or a frame of beams and columns, to carry the walls above. We design that steelwork, the lintels over new openings and the new foundations.
Foundations are where London's clay matters most. Near trees, foundations often have to go deeper, as NHBC guidance sets out, and sometimes need a different design altogether. We check the soil type against British Geological Survey records and design the foundations for the trees nearby.
Loft conversions
A loft conversion turns a roof that was never meant to carry floors into a room. We design the new floor joists, the steel beams that often replace removed roof struts and purlins, and the structure of dormers. We also check that the walls and foundations below can take the extra load.
Garden rooms and outbuildings
Garden rooms and studios need foundations suited to the soil and nearby trees too. We can design them to match the size and use of the building.
Why homeowners choose us
- Specialist structural engineers. Every beam, connection, roof and floor is designed for strength, safety and a long life.
- Designs that keep costs down. Good engineering controls the cost of materials, labour and build time.
- Clear communication. Clear timelines, plain-English updates and no hidden fees.
What we need from you
- Your architect's or designer's plans, sections and elevations.
- Photos of the existing house, particularly the walls being opened up.
- Any planning approval, and your Building Control route if you have chosen one.
What is not included
Unless your quote says otherwise, our design work does not include:
- Drainage design, above or below ground, and drainage pumps
- Temporary works and propping design
- Demolition method statements and risk assessments
- Steel-to-steel connections and steel fabrication drawings
- Steel coating details and proprietary products
- Staircases and balustrades
- Pile design, geotechnical design and site investigation
- Basement impact assessments and tanking specifications
- Construction traffic management plans
- Contamination and land remediation
Some of these, such as bespoke glazing, temporary works and steel connections, are normally designed by your contractor or a specialist. Party wall matters, and design after the Building Regulations package has been issued, are charged by the hour. The full terms are in our conditions of engagement.
Common questions
Do I need a structural engineer for an extension?
Almost always. An architect designs the layout, but an engineer works out beam sizes, materials and foundation depths so the structure carries the extra load safely for years. Building Control will want calculations and drawings for the foundations and any steel beams or lintels, and your builder needs them to price the job accurately.
Do I need planning permission for a loft conversion?
Many loft conversions are permitted development and do not need a planning application, provided they meet the conditions. These include:
- Extra roof space of no more than 40 cubic metres for a terraced house, or 50 cubic metres for a detached or semi-detached house.
- Materials similar in appearance to the existing house.
- Side-facing windows obscure-glazed and non-opening below 1.7 m above the floor.
- Nothing extending beyond the existing roof slope at the front of the house.
- Dormers set back at least 20 cm from the eaves.
You will need planning permission if the house is in a conservation area, is listed, or has had its permitted development rights removed, or if the design goes beyond these limits, as many mansard conversions do. Your architect or the council can confirm. Building Regulations apply in every case, covering structure, fire safety, insulation and the new staircase, and a Lawful Development Certificate is worth considering to show the work was lawful when you come to sell.
When should I bring in a structural engineer?
Once the layout is settled, usually after planning permission and before Building Control. Involving us before the design is finalised can help avoid an awkward or expensive structure.
What if Building Control asks for changes?
Revisions Building Control asks for within 50 days of us issuing the calculations are free. After that, and for changes you make to the design once calculations have started, time is charged by the hour, and we will tell you before any extra cost is incurred. Changes you ask for after the visit but before we start the calculations are free.
Send the calculations to your Building Control body as soon as you receive them, so any questions are picked up early.
Will my extension need deep foundations?
It depends on the soil and the trees nearby. On clay near trees, foundations may need to go well beyond the usual depth. We work this out from the ground conditions and the species, height and distance of the trees.
