Full-service structural support for extensions in Three Rivers.
Based in Manchester, with engineers around the country for site visits. We've worked extensively across Hertfordshire and know Three Rivers well — the Medieval → modern Brick semis, the party wall situations that come with them.
More importantly, we know how Three Rivers District Council’s building control team operates and we write our calculations to match. That saves time on site and avoids queries coming back.
PorthouseDean provides structural engineering for extensions, knock-throughs, loft conversions, and two-storey extensions in Three Rivers. With 240+ calculations completed across Hertfordshire, our engineers understand the area's Medieval → modern Brick semis properties, ensuring every design accounts for local building characteristics and Clay ground conditions. Our most recent project in the area was a single storey extension completed in Dec 2025.
The calculations and drawings are ours. So are the things around them that usually land on you: a date you can plan around, one place where everyone sees the same documents, and the change of mind nobody priced for. More than 9,000 projects since 2012 have run through the same process, from a single wall removal to a whole new build.
Every job runs through the same process, so every customer gets the same three answers.
Tell us about the project and we’ll tell you the price and the steps that follow. No hourly rate. If the job changes, there is a free change request on every job.
Pick how fast you need it, and pay less if you can wait. You get a date to work back from.
Never wonder where it’s up to — just look. Your project hub shows what is happening now, what is next and anything we need from you, with your drawings, documents and invoice alongside. Share it directly with everyone involved in your project.
Building control gets the calculations. Your builder gets the contractor pack. If either of them has a question about the structure, it comes to us, not to you. How we check and what the process looks like.
No extras for building control queries.
A fixed price before you commit. No obligation, no chasing.
It depends on the size and complexity of your project, so we don't publish a price range for Three Rivers. Tell us about your project and you get a clear, fixed-fee quote before you commit.
Sure, we have worked on a wide variety of Three Rivers's Medieval - modern properties. Our engineers aim to understand the specific requirements of your property from Brick semis construction, ensuring calculations that respect the original structure while meeting modern standards.
Three Rivers typically has Clay. Clay with sand seams. We factor these conditions into our foundation designs, which may affect the depth and type of foundations required.
On a full plans application, Three Rivers District Council has five weeks to decide, or longer if you both agree it in writing (regulation 14A of the Building Regulations 2010). On a building notice there is no plans decision: building control checks the work, and our calculations, as it goes. If they raise a question about the structure, your engineer answers it.
We provide structural calculations throughout Three Rivers and the surrounding Hertfordshire area. Our engineers regularly work on projects across the region, and you choose the delivery date that suits you.
If you're removing a wall, converting a loft, building an extension, or doing anything that affects the structure of your house — yes. Building control will require structural calculations before they sign off the work.
A virtual site visit is included in every quote — it's a chance to put a face to the name and talk through specific design requirements with your engineer. But we don't believe a physical visit is necessary for most residential projects. Working remotely allows us to be more economical while maintaining the same quality throughout. If your project does need a physical visit, we have engineers around the country who can arrange one.
On the date you choose when you book. The price follows the date: pick a later one and it costs less, or an earlier one if you need them sooner.
Every quote includes one free amendment because we know projects change — that's normal. Beyond that, we'll quote any further changes clearly so there are no surprises.
The quote's not the product — the project is. The moments that cost you come later: when building control query something, or your builder can't follow the drawings. That's why BC queries, an amendment and a virtual site visit are included — it's where projects actually succeed or fail.
Understanding Three Rivers's unique characteristics helps us deliver precise structural solutions.
Our team brings deep local knowledge to every project. We understand Hertfordshire’s unique building heritage – from Medieval → modern properties with their characteristic Brick semis construction. This expertise matters when calculating loads, designing foundations, and ensuring your project meets Three Rivers District Council building regulations.
Foundation design in Hertfordshire requires careful attention to local geology. The area’s Clay demands specific engineering approaches. Clay with sand seams We factor these ground conditions into every design, whether you’re planning an extension, loft conversion, or structural modification.
Comprehensive Knowledge of Hertfordshire Properties
Hertfordshire’s housing includes Suburban semis, small villages, and we’ve worked across this entire spectrum. Your project might be close to Aquadrome Country Park or positioned for excellent transport links via Metropolitan Line – either way, we know the area.
Years of working with Three Rivers District Council building control means we understand exactly what they need. Our calculations consistently pass first-time review, keeping your project on schedule.
Structural Engineering Services Throughout Hertfordshire
We provide comprehensive structural calculations across Hertfordshire (population: 94 k), covering:
• Loft conversions and dormer additions
• Rear extensions – single and double storey
• Side and wrap-around extensions
• Load-bearing wall removal calculations
• Foundation designs and underpinning assessments
Get Started With Your Hertfordshire Structural Calculations
Planning your extension or conversion? Reach out to PorthouseDean for structural calculation costs in Hertfordshire. You’ll have a clear, fixed-price quote before you commit.
Send us your plans and you'll have a clear, fixed price before you commit. Or give us a call.