Single Story Extension Cost? A Complete Guide for Leeds Homeowners
Thinking of building a single-storey extension to transform your home? Whether it’s a spacious kitchen, a light-filled dining area, or an extra living room, an extension can add serious space and value to your property. But before you start planning your dream layout, one question always comes up first:
What is the average single story extension cost?
In this guide, we’ll break down everything you need to know — from pricing factors and real-world examples to planning permission, regulations, and how to get the best results for your budget. If you’re in Leeds or West Yorkshire, this one’s especially for you.
What Is the Average Single Story Extension Cost in the UK? As of 2025, the average single story extension cost in the UK ranges between £1,800 and £2,500 per square metre, depending on specification and location.
So for a 20m² extension:
- Basic finish: £36,000
- Standard finish: £40,000 – £45,000
- High-end finish: £50,000+
However, prices can vary significantly in Leeds depending on the complexity of the build, the area of the city (e.g., central Leeds vs. suburbs like Garforth or Morley), and access to the site.
What’s Included in the Cost?
A full single-storey extension cost typically includes:
- Site clearance and excavation
- Foundations and drainage
- Brick/block work and structural steel (if required)
- Roofing (tiles or flat roof systems)
- Doors and windows (e.g., bi-folds, French doors)
- Plastering and internal walls
- Basic plumbing and electrics (sockets, lights, radiators)
- Flooring and decoration (depending on finish level)
- Building regulations approval
Optional extras like underfloor heating, Velux windows, or bespoke finishes will increase your total cost.
Key Factors That Affect Single Story Extension Cost
Several variables can influence how much you’ll pay:
1.
Size of the Extension
This is the most obvious one — the larger the extension, the more materials, labour, and time required.
- Small (10–15m²): £18,000–£35,000
- Medium (20–25m²): £40,000–£55,000
- Large (30m²+): £60,000+
2.
Site Conditions and Access
Tight rear access, uneven ground, tree roots, or drainage issues can all raise the cost due to additional groundwork or manual labour.
3.
Foundations
Most extensions require 900mm deep foundations, but if the soil is poor or drains are in the way, you may need deeper footings or piled foundations, increasing your single story extension cost.
4.
Structural Changes
If you’re knocking through to create open-plan space, you’ll need structural steelwork, possibly with new load-bearing piers or foundation pads.
5.
Finishes and Fixtures
Bi-fold doors, high-spec kitchens, natural stone flooring, or smart lighting systems can all push your extension into the high-end bracket.
6.
VAT and Professional Fees
Don’t forget to factor in:
- Architect fees: Typically 5–10% of the build cost
- Structural engineer: £400–£800 depending on complexity
- Building control inspections: £500–£1,000
- VAT: 20% on most building work unless exempt
Single Story Extension Cost in Leeds – What to Expect
In Leeds, the cost of a single-storey extension is generally on the lower-to-mid end of the UK average, unless you’re building in premium areas like Roundhay or Adel. Here’s a typical range:
- Basic spec (e.g., utility room or boot room): £1,600/m²
- Standard finish (e.g., kitchen/diner with bi-folds): £1,800–£2,200/m²
- High-spec (e.g., designer kitchen, underfloor heating, Velux): £2,300–£2,800/m²
At CG Building Services, we offer transparent pricing and full quotes across the Leeds area, tailored to your home and needs.
Do I Need Planning Permission?
In most cases, you won’t need full planning permission. A single-storey extension can often be built under Permitted Development, as long as:
- It doesn’t extend more than 3m from the rear wall (semi-detached/terraced) or 4m (detached)
- It doesn’t cover more than 50% of your garden
- It’s under 4m in height
- It uses materials similar to the existing house
Always check with Leeds City Council or ask your builder to confirm. Even if you don’t need planning, Building Regulations approval is required.
How to Keep Costs Down
Here are some practical ways to reduce your single story extension cost:
- Stick to a simple shape: Square or rectangular builds are cheapest.
- Use standard materials: Avoid expensive bespoke options unless essential.
- Reuse existing openings: Keeping existing doors/windows can cut structural work costs.
- Plan ahead: Avoid mid-build changes that increase labour or delay schedules.
- Hire a local builder: Saves travel time, supports local trades, and means better knowledge of Leeds-specific regulations.
What’s the Process Like?
Here’s a rough timeline of a standard single-storey extension in Leeds:
1.
Site Visit and Quote
A good builder will visit, take measurements, and provide a detailed quote including labour, materials, VAT, and projected timescale.
2.
Drawings and Permissions
You’ll need drawings for Building Control. Your builder may handle this or recommend an architect.
3.
Groundworks and Structure
This includes digging foundations, pouring concrete, building walls, and installing roof structure.
4.
First Fix
Electrics, plumbing, and insulation go in before plastering and flooring.
5.
Final Finish
Painting, skirting boards, flooring, doors, and any bespoke features are installed.
From start to finish, a typical 20m² extension in Leeds takes around 6 to 10 weeks.
Final Thoughts: Get the Best Value From Your Build
Understanding what impacts your single story extension cost is the key to budgeting smartly. With careful planning and the right team, you can unlock beautiful, functional space without financial stress.
Looking to build a single-storey extension in Leeds? CG Building Services has years of experience delivering high-quality builds at competitive prices. We offer:
- Free site visits and transparent quotes
- Fully managed projects from design to completion
- Expert knowledge of Leeds regulations and property types
- Friendly, local tradesmen you can trust
Contact us today to get a full breakdown of your single story extension cost and turn your plans into reality.
