Modular Glass Extensions
Less Disruption, More Living
Imagine extending your home without months of dust, noise and disruption. Our Modular Extensions are precision-built in a factory, then assembled at your home in days — not months. The same premium finish, but with up to 80% less time on site.
Call us anytime on 01243 538999 – David our digital assistant will take a few details so the right specialist can follow up personally.
What is a Modular Glass Extension?
A Modular Glass Extension gives you a beautiful, light-filled living space — without the months of disruption that come with a traditional build. Your extension is individually designed and precision-built in a controlled factory environment, then assembled at your home in a matter of days. The result is a premium finish that is often better than site-built, because every component is made under ideal conditions.
This is not a flat-pack or off-the-shelf product. Every Modular Extension from Room Outside is bespoke to your home, your proportions and your lifestyle. Patented wall panels combine steel, timber and super-insulation to deliver outstanding thermal performance with slimmer profiles — meaning more natural light and up to 15% more usable floor space compared to a traditional brick extension.
We have been designing and installing extensions across England — including West Sussex, East Sussex, Surrey, Hampshire, Kent, Essex, Greater London, Berkshire and Dorset — since 1973.
Key Benefits
Why Homeowners Choose Modular
Less disruption, faster results, and a premium finish — without compromising on quality or design.
Premium, Not Compromise
Modular does not mean lower quality — it means higher quality. 80% of construction happens in a factory under controlled conditions. No weather delays, no site variables, and every joint inspected before it reaches your home.
Your Life Back Sooner
With just 2–4 weeks on site compared to 3–6 months for a traditional build, you get your home back faster. No months of living in a building site — your extension can be watertight in as little as 2–3 days.
Comfortable All Year Round
You will actually want to use this room in every season. Patented super-insulated panels are designed to exceed Building Regulations, with an A++ thermal rating achievable — helping to keep you warm in winter and cool in summer without high energy bills.
Bespoke Design
Individually designed with choice of roof options, window placements, and finishes — oak, aluminium, timber, or uPVC. Over 50 years of project experience across England — including West Sussex, East Sussex, Surrey, Hampshire, Kent, Essex, Greater London, Berkshire and Dorset.
Modular Extension Projects & Inspiration
Recent Modular Extension projects across England — including West Sussex, East Sussex, Surrey, Hampshire, Kent, Essex, Greater London, Berkshire and Dorset. Click any image to view full size.
What You Actually Get
Every Modular Extension is individually designed and built to the same exacting standards as our site-built projects — with the added benefit of factory precision.
Slimmer Walls, More Space
Patented panels combining steel, timber, and super-insulation give you up to 15% more usable floor space than a brick extension — with slimmer profiles that let in noticeably more natural light.
New Generation Glass
Optional advanced glazing designed to help block up to 80% of solar heat while maintaining natural light. This can help maintain a comfortable temperature year-round, with A++ ratings achievable.
Weeks, Not Months
Your extension can be watertight in 2–3 days and fully finished in 2–4 weeks on site. Compare that with 3–6 months for a traditional build — that is your weekends and evenings back.
Replace Your Old Conservatory
If your existing conservatory is too hot in summer and too cold in winter, a Modular Extension can often be built on the same base — transforming it into a room you use all year round.
Better for the Environment
Up to 60% more carbon efficient than a standard brick wall, with zero waste in production. You get a premium extension and a smaller environmental footprint.
We Handle Everything
Design, engineering, planning, building control — one team manages the entire project. You do not need to hire an architect or coordinate multiple trades.
One Team, One Project, No Stress
You do not need to manage architects, builders, structural engineers and multiple trades. We handle everything — so you can focus on enjoying the result, not managing the build.
Style and Flexibility
Function and Comfort
Expert Guidance
Modular Extension vs Traditional Build
Same beautiful result, dramatically different experience during the build. Here is how the two approaches compare for you as a homeowner.
| Feature | Modular Extension | Traditional Build |
|---|---|---|
| Build method | Factory-built, assembled on site | Full brick and block on site |
| On-site time | 2–4 weeks | 3–6 months |
| Disruption | Up to 80% less | Ongoing for months |
| Thermal | A++ achievable — super-insulated panels | Varies by specification |
| Carbon | Up to 60% more efficient | Standard construction |
| Price from | £30,000 | £40,000–£80,000+ |
| Best for | Speed, quality, minimal disruption | Conventional room extension |
Not sure which approach suits your property? Our design consultants can advise during a free home visit. Book a free consultation →
Modular Extension vs Conservatory
Both create light-filled extensions, but a Modular Extension offers a different building approach.
| Feature | Modular Extension | Conservatory |
|---|---|---|
| Build method | Factory-built panels assembled on site | Glazed frame on prepared base |
| Natural light | Excellent — large glazing areas | Maximum — glass roof and walls |
| On-site time | 2–4 weeks | 8–12 weeks |
| Thermal | A++ achievable — super-insulated | A+ achievable with New Generation Glass |
| Price from | £30,000 | £25,000 |
| Garden feel | Modern, solid, room-like | Open, light-filled, garden-connected |
| Best for | Speed, insulation, solid room feel | Maximum light and garden views |
Both add valuable living space — the right choice depends on how you want the room to feel. Learn more about our conservatories →
Curious whether modular is right for your home?
Most homeowners are surprised by how premium a Modular Extension looks and feels. Book a free home visit and we will show you what is possible — with no obligation and no pressure.
Call us anytime – David our digital assistant will take a few details so the right specialist can follow up personally.
Custom Modular Glass Extension Designs & Styles
From first conversation to finished Modular Extension, here is what to expect at each stage.
Free Home Design Visit
A specialist visits your home to understand your requirements, assess the site and discuss options. No obligation, no pressure.
Design and Engineering
We produce detailed drawings and engineering plans. Your extension is designed to be factory-manufactured for precision fit. You see exactly what it will look like before committing.
Factory Build and Installation
Your Modular Extension is factory-built under controlled conditions, then delivered and assembled on site. Watertight in 2–3 days, fully complete in 2–4 weeks.
Handover and Aftercare
We do not consider a project complete until you are fully satisfied. Depending on product and location, your Modular Extension may be covered by up to a 10-year insured guarantee.
What Our Customers Say
Independently verified reviews from Google. Real homeowners sharing their experience of working with Room Outside — unedited and in their own words.
“Room Outside did an amazing job with our glass extension. The design is modern, the build quality is excellent, and the team was professional from start to finish. The space is bright, comfortable all year round, and has completely transformed our home. Highly recommended.”
“After much research I chose Room Outside. From the start the service was first class. Very impressed with the New Generation Glass and how well it controls room temperature. Team were great to have around and very polite. Would definitely recommend.”
“Room Outside provided a first class level of service throughout. We are so pleased with the installation and love our new room immensely. Things went so well from the first phone call to the day they finished.”
Modular Extension FAQs
Common questions about Modular Extension costs, timing and installation.
A Modular Glass Extension typically costs from £30,000 to £80,000+ depending on size, specification and complexity. Fully installed with building control and up to a 10-year guarantee. We provide a detailed quotation after a free home visit.
Total project timeline is typically 16–24 weeks from initial enquiry to completion. Design and planning (8–12 weeks), factory manufacturing (4–8 weeks), and on-site work (2–4 weeks). On-site disruption can be reduced by up to 80% compared to traditional builds.
Yes. Our Modular Extensions feature patented wall panels with super-insulation, designed to exceed Building Regulations for thermal performance, with the potential to achieve A++ energy ratings. They can help keep you comfortable year-round.
Planning requirements are the same as for traditional extensions. Many fall under Permitted Development Rights, but restrictions apply in conservation areas and for listed buildings. We provide full planning guidance with every project.
Yes. Thanks to the lightweight structure, Modular Extensions can often be built on existing conservatory bases, helping to save both time and cost. We assess suitability during the initial survey.
Depending on product and location, we offer up to a 10-year structural guarantee backed by independent UK insurers, alongside separate product-specific warranties. The exact terms are confirmed in your quotation.
Get Your Free Modular Extension Quote
Book a free home design consultation with our specialist team. We will discuss your vision, assess access requirements and provide a detailed quotation.
Prefer to talk? Call us on 01243 538999 — David our digital assistant will take a few details so the right specialist can follow up personally.