Single-Storey Extension in Benfleet, Essex

Single-Storey Rear Extension

A single-storey rear extension in Benfleet, Essex – open-plan kitchen, bi-folding doors, electric-opening roof windows and underfloor heating.

Project Overview

This is the second project we’ve completed for these customers. We had previously designed a rear dormer loft conversion for their mid-terrace property in Benfleet, Essex, complete with a Juliet balcony. Having already worked with us once, they came back to design a single-storey rear extension and transform the ground floor. We handled the architectural design, planning permission, structural engineering, and building regulations for the new extension.

A Repeat Customer

These customers had already worked with us once before, on their rear dormer loft conversion, before coming back to us for this extension. That’s something we’re genuinely proud of; it says more about the quality of the work and the relationship than any marketing claim could.

The Extension

We designed a single-storey rear link extension for them, with structural steelwork tying the new build into the existing house so the two work as one continuous space, kitchen and living area combined, rather than the smaller separate rooms they’d had before.

A run of bi-folding doors sits across the back of the extension, opening onto a new porcelain patio with no step between inside and out. Open them up and the boundary between kitchen and garden more or less disappears; the rear of the house reads as one continuous space rather than a room with a garden beyond it. Electric-opening roof windows sit overhead too, adding extra light and a straightforward way to ventilate the room.

Project Highlights

A closer look at the key features, finishes and practical improvements that bring the completed space together.

Open-Plan Kitchen and Island

With the extra footprint, the kitchen itself could grow properly; it's now built around an island that pulls double duty as a breakfast bar, and it's become the natural centre of the whole room as much as a practical spot for everyday use.

Rather than finishing everything as a plain modern box, we used internal brickwork as a deliberate aesthetic detail within the design. It's a small choice, but it gives the space some texture and character alongside the clean lines of the new kitchen and glazing.

Flooring, Underfloor Heating and Lighting

We fitted LVT flooring throughout the new extension, with underfloor heating underneath, keeping the open-plan space comfortable all year round. We also designed a new lighting layout across the kitchen, dining, and living areas, rather than treating lighting as an afterthought once the rest of the design was finished.

Combined with the electric-opening roof windows and bi-folding doors, the lighting and glazing work together to keep the space feeling bright and open throughout the day.

Downstairs WC

A downstairs WC was fitted into the new layout too. It's a small addition on paper, but it makes a real difference to how the ground floor functions on an ordinary day, and it was tucked in without eating into the open-plan kitchen and living area at all.

Planning Permission in Benfleet

Whether they’d need planning permission at all was one of the first things these customers wanted to know. The scope of the extension put it outside permitted development, which meant going through a full Householder Planning Application rather than a simpler route.

Benfleet properties fall under Castle Point Borough Council for planning purposes, not something most homeowners here know until they’re actually going through the process. We put the drawings together and handled the submission ourselves. The application went through cleanly on the first attempt, taking around eight weeks from submission to decision.

Structural Engineering and Building Regulations

Design took roughly a week and a half. Structural engineering and building regulations, running as their own stage afterwards, took a further two and a half weeks on top of that.

It’s worth explaining the difference between the two, since it isn’t always obvious to homeowners going through this for the first time. Planning permission looks at whether a proposed extension is acceptable in planning terms, its size, appearance, and impact. Building regulations deal with the technical side of the construction itself: structural safety, insulation, and how the building actually gets put together.

Project Costs

The professional fees for this project were:

Service	Cost (inc. VAT)
Architectural design	£1,695
Building regulations	£1,595
Structural engineering	£1,795
Total professional fees (inc. VAT)	£5,085

A build cost figure isn’t included here, as it wasn’t part of the information provided for this case study.

Considering an Extension in Benfleet or Castle Point?

The customers left a five-star review once everything was finished.

If you’re weighing up something similar for a home in Benfleet or anywhere else under Castle Point, we’d start with the design work and the planning side of things, bring in structural engineering and building regs as needed, and line up a builder we trust once the design’s approved. A free Discovery Call is the easiest way to talk it through.

Frequently asked questions

Do I need planning permission for an extension in Benfleet?

It depends on the project, but many single-storey rear extensions in Benfleet do need a full Householder Planning Application rather than falling under permitted development. For this project, planning permission was required and was approved the first time, taking approximately eight weeks. We assess the correct route for every project before any design work begins.

Who is the planning authority for Benfleet?

Castle Point Borough Council is the local planning authority for Benfleet. All planning applications, including householder extensions and alterations, are handled through Castle Point Borough Council rather than a neighbouring authority, a detail many Benfleet homeowners aren’t aware of until they start the planning process.

How much does a house extension cost in Benfleet?

For this Benfleet project, total professional fees (architectural design, building regulations, and structural engineering) came to £5,085 including VAT. Build costs vary depending on the size and specification of the extension; we provide a realistic estimate for your own property during a free Discovery Call.

What is Castle Point Borough Council's planning process for extensions?

For this project, a full Householder Planning Application was submitted to Castle Point Borough Council, with a determination period of approximately eight weeks. Planning permission was approved the first time. Building regulations and structural engineering are handled as a separate process from planning permission, covering the technical construction requirements of the work.

Project Summary

Project	Benfleet, Essex
Local authority	Castle Point Borough Council
Property	Mid-terrace house
Works	Single-storey rear extension + internal alterations
Features	Bi-folding doors, electric-opening roof windows, LVT flooring, underfloor heating, kitchen island, downstairs WC, porcelain patio
Architectural stage	Approximately 1.5 weeks
Structural engineering & building regulations	Approximately 2.5 weeks
Planning	Householder Planning Application — approved first time
Planning process	Approximately 8 weeks
Professional fees	£5,085 including VAT
Reviews	Five-star review received from client
Note	Returning client; Kirkwood previously designed a rear dormer for the same property.

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