Which Type of Extension Offers the Best Return on Investment?

Introduction

If you’re considering a home extension, one of the first questions that comes to mind is: will it actually add value to my property? Extensions can transform how you use your home — creating more space for family life, entertaining, or working from home. But they can also be a smart financial move when done right.

The truth is that not all extensions deliver the same return. Some, like loft conversions or kitchen extensions, tend to increase property value significantly, while others may add more to your lifestyle than your house price. In this guide, we’ll break down the most common extension types in the UK, their typical costs, and what you can expect in terms of return on investment (ROI).

Key Factors That Influence ROI

Before looking at specific extension types, it’s worth noting what affects the value they can add:

• Location: Properties in London and the South East often see bigger uplifts in value.
• Quality of Build: Poor workmanship can actually reduce resale appeal.
• Market Conditions: In areas with high demand for family homes, extensions that create extra bedrooms or bathrooms are especially valuable.
• Design: Well-designed spaces that flow with the existing house are more appealing than “bolt-on” extensions.

Kitchen Extensions

Why They Add Value

The kitchen is the heart of the home. A well-planned kitchen extension creates open-plan living space and adds the “wow factor” many buyers look for.

Typical ROI

• Adds 10–15% to property value
• Average costs: £40,000–£70,000 depending on size and finish
• Strongest returns in suburban family homes

Loft Conversions

Why They Work

Loft conversions are popular because they add bedrooms and bathrooms — features that directly boost resale value. They’re often possible under permitted development rights, which keeps costs down.

Typical ROI

• Can add up to 20% to property value
• Best suited for turning a 3-bed into a 4-bed, or adding a master suite
• Typical costs: £35,000–£55,000

Double-Storey Extensions

Why They’re Worth Considering

If you need significant extra space, a double-storey extension can be surprisingly cost-effective. By building upwards as well as outwards, you increase floor area without losing too much garden.

Typical ROI

• Adds 12–15% to property value
• Costs more upfront, but lower cost per square metre compared to single-storey
• Planning permission usually required

Single-Storey Rear or Side Extensions

Pros

Single-storey extensions are great for creating larger living spaces, opening up the back of the house with bi-fold or sliding doors.

Typical ROI

• Adds around 5–10% to property value
• Average costs: £25,000–£50,000
• Best viewed as a lifestyle investment rather than a pure financial one

Conservatories & Garden Rooms

Not all additional spaces are equal.

• Conservatories: Once popular, but unless high-quality and insulated, they can put buyers off.
• Garden Rooms: Fantastic for home offices or gyms, but unless fully integrated, they don’t always add much to resale value.

👉 Explore our Garden Room Ideas for lifestyle inspiration.

ROI Comparison Table

Extension TypeTypical Cost (£)Avg. Value AddedROI %Loft Conversion35k–55kUp to 20%★★★★★

Kitchen Extension40k–70k10–15%★★★★☆

Double-Storey Extension60k–100k12–15%★★★★☆

Single-Storey Rear/Side25k–50k5–10%★★★☆☆

Conservatory15k–30kLow★★☆☆☆

Frequently Asked Questions

Do all home extensions add value?

Most extensions will add some value, but the increase depends on build quality and whether the new space appeals to buyers in your area.

Which is better for ROI: a loft conversion or a rear extension?

Loft conversions usually add more financial value, while rear extensions can transform the way you live in your home.

How can I maximise ROI on an extension?

Focus on creating practical, timeless spaces that buyers want — such as extra bedrooms, bathrooms, and large kitchens. Avoid overly personalised finishes.

Conclusion

When it comes to return on investment, loft conversions and kitchen extensions consistently come out on top in the UK housing market. They not only add space but also meet the needs of today’s buyers. That said, the right extension for you also depends on how you want to live in your home.

At Universal Quality Buildings, we specialise in creating extensions that bring long-term value — both financial and lifestyle. Ready to explore your options? Take a look at our Home Extensions Service or get in touch to discuss your ideas.

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