Single-Storey Extensionsin NorthamptonMore Ground-Floor Space
Gain a bigger kitchen, family room or utility on the ground floor, with an honest QS estimate and payments tied to stages you can see.
21 years in the trade
Founder Rick Humphries started as an apprentice bricklayer at 16.
FMB & Checkatrade members
Federation of Master Builders and Checkatrade.
£5M public liability
Plus employers’ liability for all on-site personnel.
NVQ-qualified team
On-site team members hold trade-specific NVQs.
Free QS estimates
Prepared by a professional quantity surveyor for most projects.
Service overview
What single-storey extensions involve
What it is
A single-storey extension adds ground-floor space to the rear or side of your home. It is the most common way to create an open-plan kitchen and dining area, a family room, a garden room or a utility and boot room.
Who it’s for
It is for homeowners across Northampton and Northamptonshire who need more everyday living space downstairs rather than extra bedrooms, and who want to open the house up to the garden.
When you need it
It makes sense when the kitchen is too small for the way your family uses it, when there is nowhere to sit and eat together, or when the house feels dark and divided into small rooms.
Why it needs a professional
Even a modest extension involves foundations, drainage, a roof junction with the existing house and usually a steel beam where the back wall is opened up. Getting those right is what decides whether the new room stays dry, warm and crack-free.
Get it wrong and it costs you
What happens when single-storey extensions are rushed or done cheaply
Damp at the roof junction
The point where a new flat or pitched roof meets the existing wall must be properly detailed. When it isn’t, water finds its way in, often months later.
Unplanned drainage costs
Rear extensions frequently sit over or near existing drains. If this isn’t accounted for at estimate stage, it becomes an expensive surprise.
Undersized openings
The steel over the opening into the house sets how open the space feels. It needs engineer-specified steel, not guesswork.
A cold room
Poor insulation detailing creates a room that is uncomfortable in winter and costly to heat.
Common mistakes homeowners make
- Ignoring where the drains run until the footings are dug.
- Making the opening into the existing house smaller than it needs to be.
- Picking on price alone without checking what is included.
Our process
Five clear steps, start to handover
- 01
Initial enquiry & consultation
We talk through your requirements, plans, drawings or ideas, so we understand what you want the finished space to do.
- 02
Survey & quantity surveyor estimate
We assess the site, then a professional quantity surveyor prepares your estimate from the real scope. It is free for standard projects; on rare, unusually complex schemes a detailed estimate is £250 including VAT, and we tell you before any work on it starts.
- 03
Pre-commencement
Your start date is fixed and the work is scheduled. The first payment is due 72 hours before we start on site, not weeks in advance.
- 04
Staged construction
The work is delivered in 4 to 7 clearly defined physical stages, such as concrete footings, brickwork to roof plate, watertight roof and plasterboard complete. Each stage is invoiced only once you can see it done.
- 05
Practical completion
Final inspection, Building Control sign-off where applicable, handover, and a small remaining balance settled on completion.
Why homeowners choose Prime
What you get when we build your single-storey extension
Honest pricing
We give estimates, not ‘fixed quotes’ that grow later. A quantity surveyor builds the figure from the real scope of your home.
You pay for what you can see
Between 4 and 7 stage payments, each tied to a visible milestone. You are never paying far ahead of the work.
One team, every trade
Groundworks, steel, brickwork, joinery and finishes are handled by one team, so nothing falls between separate contractors.
Structural work done to calculation
Steelwork follows engineer’s calculations, from our partner local structural engineering firm or your own engineer.
Cover if something goes wrong
£5,000,000 public liability insurance, employers’ liability for all on-site personnel, and an optional insurance-backed guarantee at 15% of the final project cost.
You always know what’s next
Rick stays in contact from the first visit to handover. Reviewers repeatedly mention clear day-to-day updates and tidy, considerate sites.
In detail
Single-Storey Extensions in Northampton: methods and options
We work on homes only, never commercial property, across Northampton and the surrounding Northamptonshire towns and villages.
Rear and side extensions
+
Rear extensions push the house out into the garden and are ideal for kitchen-diners. Side extensions use the strip of land beside the house, often to add a utility, a wider kitchen or a downstairs room.
Footings and drainage
+
Concrete footings are dug and poured to suit the ground and design. Drainage under or near the footprint is dealt with before the walls go up.
Walls, steel and roof
+
Brickwork is built to roof plate, steel is installed to the structural engineer’s calculations where the existing wall is opened, and the roof is covered so the structure is watertight.
Inside the new room
+
First-fix carpentry, plasterboard, plastering and finishes follow. If the extension is for a kitchen, we can also fit the kitchen on a supply-and-fit or install-only basis.
Sign-off
+
At practical completion there is a final inspection and Building Control sign-off where applicable, with a small final balance due at handover.
Related services
Areas we cover
Before you start
Planning, regulations and living at home during single-storey extensions
How your estimate for single-storey extensions is put together
+
We don’t publish package prices, because no two homes are the same: the age of the house, the ground it sits on, where the drains run, what is hidden in the walls and the finish you want all change the cost. Instead, after a site survey, a professional quantity surveyor prepares your estimate from the real scope of work. That means labour, materials, structural elements and the order of work are all accounted for before you agree anything. For most projects this estimate is free, because we pay for the quantity surveyor’s time. Only for unusually large or complex schemes is a detailed estimate charged, at £250 including VAT, and we always tell you before any work on it starts.
We use the word “estimate” deliberately. Existing homes often reveal things once they are opened up, and pretending otherwise with a “fixed price” usually means the number either hides gaps or carries a large margin for risk. When something does change, we talk about it openly with you and agree the way forward together before carrying on.
What a stage payment looks like
+
Your project is divided into 4 to 7 milestones depending on its size and value. Typical examples are concrete footings complete, brickwork up to roof plate, roof covering watertight and plasterboard complete. Each milestone is something you can walk out and see for yourself. Only then is that stage invoiced. The first payment falls 72 hours before we start on site, and a small remaining balance is settled at practical completion and handover, so you are never paying far ahead of the work in front of you.
Planning permission and permitted development
+
Planning permission is about what a building looks like and how it affects its surroundings. Some residential work can be carried out under permitted development rights without a full planning application, while other projects need approval from the local council. Rules differ for conservation areas, listed buildings and homes where permitted development rights have been removed by an earlier condition. If you already have approved plans, we build to them. If you don’t, we’ll talk through the options at your first consultation.
Building Regulations are separate from planning
+
Even where planning permission isn’t needed, most structural and habitable work must meet Building Regulations. These cover structure, fire safety, insulation, ventilation and drainage. A Building Control inspector checks key stages, and on completion you receive the sign-off you’ll need when you come to sell or remortgage. Final inspection and Building Control sign-off, where applicable, are part of practical completion on every project we deliver.
The Party Wall Act
+
If your work involves a wall shared with a neighbour, building on the boundary, or digging foundations close to a neighbour’s property, the Party Wall etc. Act 1996 usually requires you to give them formal notice before work starts. It’s worth raising early, because notice periods need to run before that part of the work can begin.
Living at home while we work
+
Most of our customers stay in their homes throughout. Work is planned in stages so you know what is happening each week, who will be on site and what part of the house will be affected next. Reviewers regularly mention clear day-to-day updates and clean, considerate sites, the things that make living alongside a build manageable.
Questions to ask any builder
+
- Who prepares the price, and what exactly does it include?
- How much is due before work starts, and when are the stage payments?
- What insurance do you hold, and is a guarantee available?
- Who is my day-to-day contact, and how will I be kept updated?
- Do you work to structural calculations and arrange Building Control?
We’re happy to answer every one of these before you commit. Read about Rick and the team, see verified reviews, or request your estimate.
Local to Northampton
+
We’re based at The Beren, Blisworth Hill Business Park, just south of Northampton, and carry out single-storey extensions across the town and the surrounding villages, from Towcester, Roade and Bugbrooke to Moulton, Brixworth, Daventry and Wellingborough. Back to the homepage or browse all services.
FAQ
Single-Storey Extensions questions, answered
Will a single-storey extension need planning permission?
Some single-storey extensions are allowed under permitted development; others need planning permission. We can build from approved plans or take the project from concept as design and build.
Can you knock through into the existing kitchen?
Yes. Removing the existing rear wall and installing steel is a normal part of a single-storey extension, done to structural calculations.
Can you fit the new kitchen too?
Yes. We offer supply-and-fit, or install-only if you supply the units and appliances.
How long will it take?
It depends on size and design. Your estimate sets out the 4 to 7 stages the work will be delivered in.
How much will it cost?
Every home is different, so we don’t publish package prices. A professional quantity surveyor prepares your estimate from the real scope. For most projects that estimate is free; only for unusually large or complex schemes is a detailed estimate charged at £250 including VAT, and we’ll always tell you first.
Why an estimate rather than a fixed quote?
Changes often come up once work begins on an existing home. A QS-prepared estimate reflects the real scope, so you get an honest figure rather than a low number that grows later.
How do the payments work?
The first payment is due 72 hours before we start. You then pay in 4 to 7 stages, each invoiced only when that stage is visibly complete, with a small final balance at handover.
Is the work guaranteed?
An insurance-backed guarantee is available as an option, at 15% of the final project cost. We also hold £5,000,000 public liability insurance and employers’ liability insurance.
Do you take on emergency call-outs?
We carry out planned residential building projects rather than emergency call-outs. If you have a concern about your property, call Rick on 07704 675073 to talk it through.
Know the real cost of your single-storey extension before you commit
Share the basics and Rick will call you to talk it through. Free QS-prepared estimate for most projects, no obligation.
FMB & Checkatrade members · £5M public liability · Pay only for stages you can see