Is Replacing a Conservatory with Extension Really Worth It?

Replacing a conservatory with an extension is often the smartest upgrade a UK homeowner can make. A properly insulated single-storey extension delivers year-round comfort, lower energy bills, and a space you’ll use every day. Better yet, with our modular system, you can have it watertight in just seven days.

According to the GOV.UK Part L 2025 guidance, modern walls and roofs lose less than half the heat of old glazed rooms, while modular builds cost up to 40% less in labour. If your current conservatory is draining energy instead of adding value, read on. We’ll show you where an extension wins, what it costs, and how swiftly it can transform your home.

1. Five Reasons to Replace Your Conservatory with an Extension

Let’s be honest: conservatories haven’t aged well. Here are five reasons why more homeowners are ditching the glass and going for a proper extension instead:

Comfort, all year round: Say goodbye to cold snaps and greenhouse summers. A fully insulated roof and walls keep your space cosy and consistent in every season.
Built in days, not months: Our pre-fabricated extensions are installed up to six times faster than a traditional build, with minimal mess or disruption.
Add real value: A single storey extension, done right, can boost your home’s value by as much as 20–23% depending on location and layout.
Cut your energy bills: With U-values that meet Building Regulations (Part L), you’ll spend less on heating compared to a draughty conservatory.
Compliant, insurable, future-proof: Every extension we build is fully compliant with Building Control and comes with a 10-year manufacturer’s warranty. So it’s not just better to live in, it’s easier to sell too.

2. Real Homeowners, Real Results: Mrs Madison’s Story

When Mrs Madison reached out, her conservatory had become a daily frustration. It was far too cold for the kids, too hot by midday, and barely used at all. With her daughter, partner, and newborn moving in, they needed extra living space fast, but couldn’t face a drawn-out build.

We replaced the glass box with a fully insulated kitchen-diner using our modular system. From tear-down to watertight took just seven days. Even with a few calendar clashes, the build was completed in under three weeks. That’s only a small part of the 12+ weeks she expected for a traditional build.

“The main reason we went for this type of extension and this factory-built modular thing was because of the quickness… and the simplicity. It was pretty effortless and without much disruption.”

— Mrs Madison

Not only was the build faster, but it also cost less than half of a conventional alternative. And with a warmer, brighter, and more usable space, the whole family now gets more from their home, without the wait.

Stories like hers are exactly why we do what we do. You can read more real experiences over on our testimonials page.

3. How Much Does It Cost in 2025?

What does it cost to replace a conservatory with an extension?

Removal of the old structure: Typically £2,000–£5,000
Modular extension build: From £1,200 per m² (vs. £2,400+ for traditional)*
Upgraded foundations (if needed): £5,000–£15,000
Building Control & professional drawings: Typically £750–£1,500

Because modular elements are pre-built off-site, you save significantly on labour and delays. Homeowners who switch to modern construction methods can save as much as 35% on total costs, says the ONS Construction output price indicies.

And remember, you’re not just replacing glass with bricks. You’re gaining insulation, property value, and a room designed to last.

4. Planning Permission, Building Control, & the 10-Year Rule

Do you need planning permission? Most homeowners don’t. Stay within height and depth limits, and your project should qualify under Permitted Development. What you always need is a Building Control sign-off, and we handle that paperwork for you.

Our friendly three-step roadmap:

We file the paperwork. You relax while we submit drawings and a build notice.
Mid-build checks. An inspector visits to approve the footings, insulation, and structure.
Completion certificate. Proof your new room is safe, legal, and fully insurable.

Worried about the so-called 10-year rule? GOV.UK guidance confirms that relying on unauthorised work, escaping enforcement, is a risky business. Building it right the first time is faster, safer, and protects resale value. For a deeper dive, see our plain-English guide on building regulations for extensions.

5. Why Modular Wins: Faster Builds, Lower Bills

How quickly can a modular extension be installed?

Day 1: Conservatory out, foundations laid.
Day 3: Pre-made pod walls and roof craned into place.
Day 7: Watertight shell, ready for plaster.

Less time on site means minimal mess, fewer trades underfoot, and a quicker return to everyday life. Better still, our insulated roof panels achieve U-values below 0.18 W/m²K, which is comfortably ahead of Part L 2025 targets. Thanks to this, most clients shave 15–20% off annual heating bills.

Trade Glass for Comfort

Replacing a conservatory with an extension means that your next favourite room is closer than you think. Swap out draughty glazing for fully insulated, regulation-ready rooms. They work every day of the year, lower energy bills, and can increase your home’s value by over 20 per cent.

However, if that chilly, sun-blasted space isn’t working anymore, picture it as a warm kitchen-diner, a peaceful home office, or a bright playroom. All set before the next season arrives. With more than 1,000 modular extensions completed, Single Storey Extensions know how to keep the process swift, compliant, and stress-free. Ready to re-imagine your space?

Call 0331 630 2550 or get a quote online and chat through your ideas with our friendly team.