9 Brilliant Single Storey Side Extension Ideas: Cost, Pros & Cons

Did you ever feel like your home needs just a little more space, but you’re not quite sure how to make it happen without a shift? Why don’t you just sit back, spend a few minutes on reading the stunning single storey extension ideas that can elegantly transform your home by adding more space. 

To increase your living space without any stress, a single storey extension can be  a perfect solution for the homeowners of the UK. If you are after a bigger kitchen, or a peaceful reading nook, Paramountbuilt have compiled 9 of the best single storey extension ideas, along with its cost, pros and cons, so that you can make the right move for your home and budget. 

Let’s dive into some inspiring and practical trendy ideas that can genuinely transform your home. 

Open-plan kitchen-diner side extension 

If you dream of a sociable, airy space where cooking and conversation flow together, an open-plan kitchen-diner side extension is ideal. It completely redefines your ground floor by blending your kitchen, dining, and even living area into one seamless hub of the home. 

Average cost: £45,000 to £65,000

Pros: 

• Add huge resale value 
• Creates a sociable, functional space
• Let in natural light with roof glazing or bifold doors

Cons:  

• Can reduce garden width
• May need structural steel for support 

Side utility room or laundry area 

Adding a utility room in the side return is a smart way to manage everyday mess. It gives you a practical space for laundry, cleaning supplies, and even coats and shoes, keeping your kitchen and living areas clean and organised. 

Average cost: £25,000 to £35,000

Pros: 

• Keep main areas clutter-free 
• Can double as a boot room 
• Adds functionality without needing extra floor area

Cons:  

• May feel small unless planned smartly
• Not always a “wow” feature for buyers

Home office or studio 

Working from home? A dedicated home office in your side extension creates a quiet, professional space that’s separate from family noise. You can create a design with built-in desks, shelves,and optimal lighting for productivity all day long. 

Average cost: £30,000 to £40,000

Pros: 

• High ROI for remote professionals 
• Adds separation between work/home
• Compact and easy to heat or cool

Cons:  

• May require soundproofing 
• Light access might be limited depending on the location 

Glass box side extension 

A glass box extension along the side of your home is ideal for those who want something sleek and modern. With frameless glazing and minimal walls, it makes even a small space feel brighter and bigger, perfect for showcasing your garden from the patio. 

Average cost: £55,000 to £85,000

Pros: 

• Striking visual appeal 
• Maximise daylight 
• Great connection to the garden

Cons:  

• Less insulation than solid walls
• Can be expensive due to custom glazing

Side living room or snug 

Turning your side into a peaceful, cosy spot with a snug or second lounge could be a great idea. No matter if it is a quiet reading nook, a family tv space, or somewhere to unwind , this extension offers warmth and comfort with a touch of privacy. 

 Average cost: £35,000 to £55,000

Pros: 

• Ideal for reading of TV time
• Easy to decorate and personalise 
• Add informal space 

Cons:  

• Less light than open-plan living 
• May not suit very small homes 

Playroom or kids’ zone 

Got little ones with endless energy (and toys everywhere)? Turn that unused side space into a vibrant kids’ playroom. It’s a great way to keep the mess contained and give your children a room of their own to play, create, and grow. 

Average cost: £30,000 to £45,000

Pros: 

• Keeps kids’ ess in one pot 
• Easy to repurpose as they grow 
• Enhance lifestyle functionality 

Cons:  

• Might feel underused later on 
• Can require enough flooring and material

Side extension with a skylight roof 

If your side return is narrow or doesn’t face much light, a skylight roof is a game-changer. It brings in sunlight from above and transforms the space below into a bright, inviting zone, perfect for kitchens, offices, or living areas. 

 Average cost: £40,000 to £60,000

Pros: 

• Brings light into the dark side returns 
• Look great from inside 
• Avoid privacy issues from side windows 

Cons:  

• Skylights may cause heat loss in winter 
• Needs careful insulation and water proofing 

Cloakroom & ground floor WC

A downstairs cloakroom with a toilet and basin is one of the most practical side extension ideas. It’s ideal for guests or families with young kids and makes daily life easier, especially in homes with only an upstairs bathroom. 

Average cost: £20,000 to £30,000

Pros: 

• Highly practical day-to-day 
• Great for elderly visitors 
• Increase the property’s functionality 

Cons:  

• Less visual impact 
• Limited resale value boost 

Side extension with courtyard garden 

Blending your side extension with a private courtyard garden for the ultimate indoor-outdoor feel is also a good option. A lightwell or planted patio next to your new room adds fresh air, views, and style, perfect for morning coffees or evening relaxation. 

Average cost: £50,000 to £70,000

Pros: 

• Bring nature into your home
• Improves air and light flow 
• Can be visually stunning 

Cons:  

• Needs clever layout planning 
• Courtyard upkeep adds extra efforts 

 Pro Tip: Learn about costs, types and benefits for Single Storey side extensions

Quick comparison table 

Which side extension idea is best for you?

Choosing the right single-storey extension depends on how you live and what you need more of. Are you looking to work smarter from home? Or maybe just declutter your life with extra utility space? Whatever your goal, there are a lot of side extension ideas to match. 

Remember, the costs mentioned here are average estimates. Your final budget could vary based on location, material quality, and builder rates. So always consult with your architects or contractors early in the planning process.   

Bonus tips: planning permission & regulations

Many side extensions fall under permitted development, but not all. Here’s what to keep in mind: 

• Max height of 4 meters
• The width can’t exceed more than half the width of the house 
• Materials should be similar in appearance to the existing house 

Always check with your local authority or a quality architect to confirm whether you need full planning permission.