- House Extension services
House Extension Builders
Create More Space with Trusted House Extension Builders
BBS Design Build Transform is a house extension company that provides fully managed house extensions to add space, improve how a home works and add long-term value. As experienced house extension builders, the team handles design, planning, construction and finishing in one project, with a focus on quality workmanship and clear, itemised quotations. Single-storey, double-storey, rear and wrap-around extensions are all available.
Start Your Project—Get a Fast, Free Estimate
No obligation. Get expert advice and a custom quote today
What Is a House Extension?
A house extension adds extra living space to your existing home, whether at the rear, side or upper floor, depending on your property and requirements.
For many homeowners, extending is a practical alternative to moving, allowing you to create a larger kitchen, additional bedrooms or bathrooms, a home office, or a more functional living space while adding long-term value to the property.
A well-designed extension can improve storage, increase natural light, strengthen the connection to the garden and make your home work better for everyday living.
A quality extension can make a real difference to how your home works day to day.
Is a House Extension the Right Option for You?
More Space for Your Home
If your existing rooms feel cramped or you cannot find enough space for your family to live comfortably, a house extension can give you the extra space you need without compromising on the location you already love.
Your Family Is Expanding
Many homeowners choose to extend, especially when they need more bedrooms, a larger kitchen or additional bathroom facilities to suit a growing family.
Need a Flexible Space or Home Office
With remote working, dedicated office space has become more important than ever. An extension can create a comfortable home office, a playroom, a bedroom for guests or a flexible multi-purpose space that evolves with your changing needs.
Want to Add Value to Your Property
Well-planned extensions can improve both the everyday usability and the market value of a property, which makes them a worthwhile long-term investment for many homeowners.
Types of House Extensions We Build
We design and build house extensions to suit your property, lifestyle and family needs.
Single Storey House Extension
A single-storey extension to a house is ideal if you want to make a larger kitchen, dining area or family room with easy access to the garden. It is one of the most popular extension options for modern open-plan living.
Double Storey and First Floor Extensions
Two-storey extensions provide a large amount of extra space on both floors and are commonly chosen by homeowners who need extra bedrooms, bathrooms or a separate home office. We also take on second-storey extension projects for properties where extending upwards is the most efficient use of space.
Rear House Extension
A rear extension is a common way to build a larger kitchen and living area and improve the connection to the garden. Rear house extensions can transform underused outdoor space into bright, open-plan areas that are better suited to modern family living.
Side Return and House Side Extensions
Side return extensions make use of the often narrow space down the side of older terraced or semi-detached houses, creating a wider, more usable kitchen or dining room.
Wrap-Around Extensions
A wrap-around extension is a combination of a rear extension and a side return extension, creating a large open-plan living space with plenty of natural light and flexibility.
Pitched Roof Extensions
Many styles of property benefit from a pitched roof extension because of its traditional look, better drainage and scope for improved insulation and vaulted ceilings.
Living Room Extensions
A living room extension provides a larger, more comfortable family space, making it easier to host visitors, relax together and enjoy better natural light throughout the day.
What’s Included in Our House Extension Service?
BBS Design Build Transform provides a fully managed extension service, taking care of every stage of the project from the initial consultation through to final handover.
Free Consultation and Property Evaluation
We start with a free consultation and a detailed assessment of your property to understand your goals, your budget and the most suitable extension options for your home.
House Extension Design & Plans
We prepare the extension design, layout options and technical drawings needed for planning applications and construction.
Itemised Quotation
Before any construction begins, we provide you with a complete fixed-price quote covering the work, materials, specifications and costs.
Structural & Groundworks
We carry out all the structural work, foundations, drainage and groundworks to make sure your extension is built on a stable and compliant base.
Construction & Project Management
Our experienced site team takes care of the whole building process, managing trades, scheduling work and maintaining quality control throughout the project.
Interior Finishing
We complete all internal work, including plastering, flooring, electrical and plumbing installation, decoration and final finishing details.
Final Inspection & Handover
Before handover, we carry out a full quality inspection, fix any snagging issues and make sure your new extension is ready for you.
House Extension Services in Your Area
BBS Design Build Transform’s house extension specialists cover Harrow, Wembley, Edgware and London.
Bespoke house extension services in Harrow, including single-storey, rear and wrap-around styles, with fully managed design, planning, construction and interior finishing.
An experienced team delivering fully managed house extensions across London, including rear, side and wrap-around styles, with expert design, planning and construction support.
Create more space with expertly designed house extensions in Edgware, including open-plan kitchens, additional bedrooms and modern family living areas.
Fully managed house extensions in Wembley, including rear, side return and wrap-around styles, with design, planning, construction and finishing handled by one team.
Frequently Asked Questions
What size extension can be built without planning permission?
Under permitted development, a single-storey rear extension on a detached house can extend up to 4 metres from the original rear wall, and up to 3 metres on a semi-detached or terraced house. Larger extensions of up to 8 metres (detached) or 6 metres (semi-detached and terraced) can go through the prior approval route, which includes neighbour consultation. These limits apply to houses, not flats, and other permitted development conditions still apply. BBS Design Build Transform checks each property against these limits before design begins.
Is planning permission needed for a single-storey extension?
Not always. A single-storey extension within the permitted development limits for depth and height can go ahead without a planning application. Side extensions must not exceed half the width of the original house, and permitted development rights are more restricted in conservation areas and other designated land, where planning permission is usually needed. BBS Design Build Transform confirms the position for the property and prepares any application required.
Do house extensions need Building Regulations approval?
Yes. Building Regulations approval is needed even when planning permission is not. It covers structural safety, fire protection, insulation, ventilation and drainage, and it is applied for before work starts. BBS Design Build Transform prepares and submits the Building Regulations application as part of the project.
How long does a house extension take?
On site, a single-storey extension typically takes around 6 to 16 weeks, depending on how much internal work is involved. Double-storey extensions usually take longer. Design, planning and Building Regulations approval come before construction and add to the overall timeline. BBS Design Build Transform agrees a programme after the site evaluation, so the schedule is clear before work starts.
How is a house extension built, step by step?
A house extension follows a set order: site evaluation, design and plans, planning and Building Regulations approvals, groundworks and structure, construction and interior finishing, then final inspection and handover. House extension builders such as BBS Design Build Transform manage all of these stages in one project, with a single point of contact from the first visit to handover.
Is it possible to live in a house during an extension?
In many cases, yes. This is most likely with a rear or side extension, where the existing rooms stay in use. Extensions that involve the kitchen, bathrooms or major internal alterations can disrupt daily life for a period. BBS Design Build Transform discusses access, working areas and any temporary arrangements during the site evaluation, so the plan is agreed in advance.
Does a house extension add value to a home?
A well-designed extension that adds usable floor area, such as an extra bedroom, a larger kitchen or a family room, can add long-term value. The effect depends on the property, the location and the quality of the work. BBS Design Build Transform focuses on quality workmanship and finishes that match the existing home.
Is an architect needed for a house extension?
Planning and Building Regulations applications both need drawings, but a separate architect is not always necessary. BBS Design Build Transform provides design and plans as part of its house extension service, and arranges structural design where it is needed.
Testimonials
Start Your House Extension Project
Whether you’re planning a single-storey extension, a larger family extension or a complete design and build project, our team is here to help.
We offer free consultations, fixed-price quotations and expert guidance from planning through to completion, helping you create a home that is more spacious, functional and valuable.
Let’s discuss your extension ideas and explore the best way to create the extra space your family needs, with professional advice, transparent pricing and high-quality workmanship from an experienced local team. Contact us today!
