Want to add more space to your home without moving house?
Single-story extensions could be your answer. With 1 in 5 UK homeowners planning a major home renovation project in 2024, getting your extension costs right has never been more crucial.
Here’s the problem:
Extension costs are all over the place. One quote could be £30,000, another £80,000 for the same project.
The good news?
There’s a proven way to get incredible value without getting ripped off.
What you’ll discover:
- Understanding Single-Story Extension Costs
- The Real Cost Breakdown You Need to Know
- How to Balance Quality and Budget
- Smart Ways to Save Without Compromising
What Are Single-Story Extension Costs Really Like?
Single-story extension costs in the UK? They’re not what most people think.
The reality?
Single-storey extension costs range from £20,000 to £60,000 depending on what you’re building. That’s a huge gap.
Want to narrow it down? The average single storey extension cost sits between £1,500 and £2,500 per square metre. Much clearer picture, right?
Here’s what this means in real money:
A basic 20m² extension? £30,000-£40,000. Go for premium finishes and you’re looking at £50,000+.
Want specifics? A simple rear extension with basic kitchen units, standard tiles, and painted walls hits the lower end. Add bifold doors, underfloor heating, and quartz worktops? You’re pushing towards that £50,000+ mark fast.
The difference? Quality of materials, complexity of the build, and where you live.
The Hidden Cost Drivers Most People Miss
Understanding what pushes single-story extension costs up is the key to staying on budget.
Size is obvious.
Double the size, roughly double the cost. But here’s what catches people out…
Location makes a massive difference.
London and the South East? Expect to pay 30-50% more than in the North. Same extension, same quality, totally different price.
Material choices can double your bill.
Basic materials keep costs down. Premium finishes? They’ll blow your budget fast. The trick is knowing where to spend and where to save.
Take flooring. Basic laminate costs £15-£25 per square metre. Engineered hardwood? £40-£80 per square metre. Natural stone tiles? £60-£150+ per square metre. Same room, same function, massively different costs.
Planning costs add up.
Most single-story extensions fall under permitted development rights. Great news. But you’ll still need building regulations approval. Budget £1,000-£2,000 minimum.
Here’s what people forget: Even under permitted development, neighbours can object. Takes time and sometimes money to resolve. Planning application fees alone? £206 in England. Building control fees? Another £500-£1,500 depending on project size.
How Much Should You Budget?
Getting your budget right from day one? Critical.
The breakdown that works:
For a decent 20m² rear extension, budget £40,000-£50,000. This covers everything from digging foundations to final paint.
But here’s what kills budgets…
Hidden costs no one tells you about.
Things like:
- VAT at 20% on everything
- Temporary kitchen setup while work’s happening
- Ground problems requiring extra foundation work
- Electrical upgrades to meet current regs
Smart approach? Add 20% to whatever quote you get. Better to have money left over than run out halfway through.
Why 20%? Because that’s what most successful extension projects actually end up costing above the original quote. Preparation beats panic every time.
The Quality vs Cost Sweet Spot
This is where most people get it wrong…
Going cheap costs more in the long term.
With the UK home improvement market worth £29.7 billion in 2024, there’s no shortage of builders. The problem is, not all are worth hiring.
Here’s how to nail the balance:
Never compromise on structure, waterproofing, or insulation. These aren’t areas to cut corners.
Where you can save money:
Interior finishes. Start with good basics and upgrade later when budget allows.
The sweet spot?
Aim for “good” quality rather than basic or premium. Around £2,000 per square metre gets you a solid extension with decent finishes.
What does “good” quality actually mean? Branded kitchen units (not budget, not luxury), decent tiles, quality windows with proper guarantees, solid electrics and plumbing. Won’t win design awards but will serve you well for decades.
Proven Ways to Reduce Extension Costs
Want to keep costs down without sacrificing quality? These strategies work…
Timing matters.
Winter months often see lower demand. Better prices from contractors who want the work.
Do some work yourself.
Not the structural stuff – leave that to the pros. But painting, basic landscaping, even some interior work? Huge savings.
Buy your own materials.
Builders mark up materials. Buy your own windows, doors, and fixtures? It could save thousands.
Here’s the reality: Most builders add 10-20% markup on materials. On a £40,000 project, that’s £4,000-£8,000 extra. Worth shopping around for.
Keep the design simple.
Complex shapes and fancy roof designs cost more. A simple rectangular extension with straightforward roofing? Always cheaper.
Getting Maximum Value From Your Investment
The secret to affordable single-story extensions isn’t spending less…
It’s spending smart.
Always get multiple quotes.
Three minimum. Helps you spot outliers and understand market rates.
Check what’s actually included.
Cheap quotes often exclude essentials. Building regs, skip hire, final cleaning – make sure you’re comparing like with like.
Look beyond the price.
Cheapest isn’t always the best value. Check reputation, timeline, and guarantees offered.
Timeline and Extra Costs to Expect
Most single-story extensions take 12-16 weeks. But several things affect this…
Planning and design: 4-8 weeks
Includes designs, planning apps (if needed), and building regs approval.
Construction: 8-12 weeks
From breaking ground to final snag list.
Extra costs during build:
Temporary living arrangements. Kitchen out of action? Budget for eating out or a temporary cooking setup.
Storage might be needed for furniture and belongings.
Making Your Extension Add Real Value
Single-story extensions can add serious value. The key? Doing them right.
Focus on what buyers want.
Kitchen extensions and extra living space top the list. Best return on investment every time.
Design for flexibility.
Open-plan spaces that adapt to changing needs serve you better long-term.
Don’t over-improve for your area.
While you want quality, avoid creating the most expensive house on your street.
Finding the Right Builder
Your project’s success depends on who builds it.
Research thoroughly.
Check reviews, ask for references, and visit previous jobs if possible. Good contractors are happy to show off their work.
Verify credentials.
Proper insurance and trade body registration aren’t optional.
Get everything in writing.
A detailed contract protects everyone. Include materials specs, timeline, and payment schedule.
Payment schedule matters. Never pay large sums upfront. Standard practice? 10% deposit, progress payments tied to completion stages, final 10% on completion. Protects your money and keeps contractors motivated.
Wrapping It Up
Single-story extension costs don’t have to be scary when you know what you’re doing.
The bottom line?
A well-planned, quality extension typically costs £40,000-£60,000 for most UK homeowners. This investment can add significant value while giving you the space you need.
Remember: The cheapest option is rarely the best value. Focus on getting quality work at a fair price.
By understanding the real costs and planning carefully, you can create an amazing extension that serves your family for years without breaking the bank.
Start with a clear budget, get multiple quotes, and choose quality where it matters.
