Rear House Extension in Southend-on-Sea (Wenham Drive) – RSJ & Open Plan Kitchen
We recently completed a full rear house extension project in Southend-on-Sea (Wenham Drive), transforming a dark, enclosed kitchen into a large, modern open-plan living space. This end-of-terrace property underwent a complete structural and internal redesign, including steel installation (RSJ), underpinning works, drainage modifications, and a full high-spec kitchen fit-out.
This project covered everything from initial groundworks and structural planning to final decoration, delivering a high-quality extension built to modern standards and fully approved by building control.
Project Overview
- Location: Southend-on-Sea, Essex (Wenham Drive)
- Property Type: End of terrace house
- Extension Size: Approx. 6m x 4m
- Final Open Space: Over 40m² open-plan kitchen and living area
- Build Time: 2.5 months (start to finish)
- Budget: £55,000–£60,000 (excluding kitchen and finishing materials)
This rear house extension in Southend-on-Sea significantly improved the layout and property value.
🔧 Scope of Work
This was a full-service project delivered from start to finish, including:
Rear extension construction
Excavation and foundations
Structural steel installation (3 RSJ with additional steel beams)
Underpinning of existing structure
Demolition of internal walls and chimney base
Installation of aluminium bifold doors (3-panel, anthracite grey, slim profile)
Large feature skylight + secondary opening skylight above kitchen
Warm roof system construction
Silicone render (external finish)
Full kitchen installation
Plumbing and electrical works
Underfloor heating across entire space
Karndean flooring installation
Plastering, decorating, and finishing
👉 In short: everything from ground to final finish
Structural Engineering & Planning
From the early stages, this project required close coordination with structural engineers and building control.
All necessary approvals were obtained before starting, ensuring full compliance with UK building regulations. The structure relied heavily on steel support, requiring precise installation and load distribution.
Three RSJ beams combined with additional steel elements were installed to support the upper structure after removing load-bearing walls and part of the chimney.
Challenges & Solutions
This project presented several complex challenges that required experience and problem-solving on-site.
1. Drainage & Soakaway Limitations
Due to limited space on the property, installing a traditional soakaway system was not feasible.
Solution:
We successfully obtained approval from the water authority to connect the new extension to the existing sewage line. This required careful planning and compliance with regulations, but ensured proper drainage without compromising the design.
2. Weak Existing Foundations
The original structure had relatively shallow and insufficient foundations, especially problematic once the internal walls were removed and loads transferred to steel beams.
Solution:
We carried out underpinning works to reinforce the structure and provide adequate support for the new load distribution.
This involved:
- Excavation alongside existing foundations
- Manual digging underneath the structure
- Installation of reinforced support sections
Due to restricted access, much of the work had to be completed by hand, requiring both specialist equipment and significant manual labour.
3. Structural Reconfiguration
The removal of internal walls and the lower section of the chimney significantly altered the load paths within the property.
Solution:
The upper section of the chimney was supported using RSJ beams, allowing the space below to be fully opened while maintaining structural integrity.
Design & Features
The final design focused on creating a bright, modern and functional living space.
Key Features:
- Large open-plan layout (40m²+)
- Three-panel aluminium bifold doors in anthracite grey
- Slimline profiles for a modern look
- Integrated blinds within glazing (dust-free, maintenance-free)
- Large self-cleaning skylight for maximum natural light
- Secondary opening skylight above kitchen area
- Underfloor heating throughout
- High-quality Karndean flooring
- Modern kitchen with island
- Full lighting design with recessed spotlights
🏗️ Construction Details
The extension was built using a warm roof system, improving energy efficiency and thermal performance.
Externally, the property was finished with silicone render, providing a clean modern appearance and long-term durability.
Internally, all works were completed to a high standard, including plastering, decorating, flooring, and full installation of kitchen and services.
⏱️ Project Timeline
The entire build was completed in approximately 2.5 months, including:
- Groundworks and foundations
- Structural work and steel installation
- Roof construction
- Internal works and finishing
Despite structural complexity and access challenges, the project was delivered efficiently and passed building control inspection without issues.
✅ Final Result
The transformation was significant.
The client moved from a small, dark and enclosed kitchen into a large, bright open-plan space combining kitchen and living area.
Key improvements:
- Dramatically increased natural light
- Seamless connection to the garden via bifold doors
- Modern, spacious layout
- Improved functionality and comfort
- Increased property value
The removal of the chimney base and internal walls allowed for a fully open layout, while the structural steel ensured long-term stability.
Client Outcome
The new space completely changed how the property is used.
Instead of a cramped and outdated kitchen, the client now enjoys:
- A modern open-plan living environment
- A large kitchen with island
- A bright and welcoming space for everyday living and entertaining
Looking for a Rear Extension Builder in Southend-on-Sea?
If you’re planning a house extension in Southend or Essex, BTOM Construction Limited provides full-service builds from start to finish.
We handle:
- Structural work (RSJ installation)
- Extensions and open-plan conversions
- Kitchens and full refurbishments
- Foundations and underpinning
- Building control and compliance
Contact us today for a quote and expert advice on your project
Frequently Asked Questions – Rear Extensions in Southend
How much does a rear extension cost in Southend?
Most rear extensions in Southend cost between £1,800–£2,500 per m² depending on specification and structural requirements.
Do I need planning permission for a rear extension?
Many rear extensions fall under permitted development, but structural changes and steel installation require building control approval.
How long does a rear extension take?
A typical rear extension takes between 8–12 weeks depending on complexity and structural work involved.
Why Choose a Local Builder in Southend-on-Sea?
Choosing a local builder in Southend-on-Sea ensures faster response times, better communication, and a smoother building process from start to finish. Local builders understand the specific requirements of properties in the area, including ground conditions, common construction methods, and structural challenges typical for homes across Essex.
Working with a Southend-based builder also means better coordination with local building control, helping avoid delays and ensuring full compliance with UK building regulations.
At BTOM Construction Limited, we specialise in rear extensions, RSJ installation, and kitchen extensions in Southend-on-Sea, delivering reliable, high-quality results with proven local experience.