How Much Does a Bungalow Extension Cost in the UK?

The average bungalow extension cost ranges from £30,000 to £180,000.

A modest, single storey bungalow extension can often be completed for well under £50,000. However, when the size and specification of an extension increase, so does the price. 

Large double storey bungalow extensions cost the most, averaging £100,000 to £180,000. This is because they require significant changes to both the roof and the foundations. 

Whether you’re in search of budget-friendly ideas or ways to truly maximise the value of your bungalow, discover what WhatPrice users have paid for their bungalow extension and why in this guide. 

Introduction

Bungalows, by their very nature, are often much smaller than other types of properties. While this makes them a top choice for those who want the freedom of step-free living, sometimes the lack of space can ultimately result in another type of limitation. 

Whether your bungalow doesn’t have enough rooms to meet the needs of your family, or simply suffers from a poor layout, a bungalow extension can offer you the perfect remedy.

Crucially, extending your bungalow means you don’t have to move to gain the extra space and functionality you need. 

What is a bungalow extension?

A bungalow extension involves adding more usable living space to a bungalow. 

However, not all property extensions are created equal! Unlike extending a typical two storey home, it’s not as easy to expand upwards with a bungalow. A double storey bungalow extension is certainly possible, although significant roof alterations would be needed. 

Instead, most bungalow extensions are built outwards into the garden, such as a rear kitchen extension or a side extension. 

Loft and garage conversions are also popular options for renovating a bungalow, especially for creating an additional bedroom.

The types of bungalow extensions include:

• Rear extension
• Side extension
• Wraparound extension
• Loft conversion
• Dormer conversion
• Garage conversion

The feasible options will depend on the amount of usable land which surrounds your property, any planning constraints which may apply and your budget. 

Why consider extending a bungalow?

• You want more space but you don’t want to move
• To solve current or future accessibility challenges
• Increase the property value
• Modernise the feel of your home
• Add functionality i.e. an extra bedroom, home office or another bathroom

Overview of costs and key considerations

Bungalow extensions can be more expensive, because every new area will require fresh foundations as well as a roof. 

That said, the cost of a single storey structure is comparable to extending the ground floor of any other property. 

With so many options available in terms of the size, shape and overall scale of your bungalow extension, you can choose an option which suits your budget. 

Just be aware of the differences in the structure of a bungalow compared with a traditional home, as the work to add extra living space may involve different steps. 

How much does a bungalow extension cost in the UK?

WhatPrice users have reported paying between £1,400 and £3,000 per square metre to extend their property.

The true cost will depend on the type of extension, its size and the level of specification you choose. Your location in the UK also counts, with extensions in London and the South East costing significantly more than in the North. 

Bungalow extension cost by type

Bungalow extension type	Common uses	Typical cost	Considerations
Side return extension (30 sqm)	Fixing functional layout challenges.	£30,000-£40,000	Will usually require a party wall agreement.
Rear extension (30 sqm)	Extending the kitchen, dining and living areas, usually as one large open plan space.	£37,000-£80,000	Will reduce your garden space. Landscaping work will also be needed to create a seamless transition to the outside space from the new structure.
Loft conversion	Creating an extra bedroom or home office.	£20,000-£40,000	The loft will need stairs for access.
Dormer extension (Mansard roof and additional rooms added)	Adding extra bedrooms and usually an en-suite.	£38,000-£91,000	Dormers help provide more usable headroom than a sloped roof, but give less space than hip to gable conversions.
Wraparound extension (45 sqm)	Fixing an awkward layout while also adding extra rooms downstairs.	£65,000-£120,000	Requires knocking down multiple external walls to be able to extend them.
Two storey bungalow extension (60 sqm)	Adding significantly more living space to a bungalow, including multiple new rooms.	£100,000-£180,000	Will need more extensive foundations and ultimately is always the most complicated and costly option.

As noted above, extending a bungalow can sometimes be more expensive than the cost of extending a typical property.

Thankfully, there are also lots of budget-friendly options for extending a bungalow. WhatPrice users have reported paying as little as £20,000 for a loft conversion, which would avoid the need to extend. The cheapest type of extension for a bungalow is a side return extension, starting at £30,000.

On the other end of the scale, double storey extensions for a bungalow are a significant project. As such, they also have the highest costs associated ranging from £100,000 to £180,000 for an average sized extension of 60 sqm. 

Of course, if you are planning to add more than 60 sqm of space across two floors of your bungalow, the costs will be even higher. This is especially the case if you live in London, or are opting for a high specification, architecturally-led design. 

Factors affecting the cost of a bungalow extension

Why do some bungalow extensions cost as little as £30,000 and others £180,000?

At every stage of the project, you will have a lot of options. Some decisions will work for a modest budget, whereas others are only going to be doable with a significant financial investment. 

It’s time to learn what these are so that you can manage your expectations, based on how much you’re willing to spend on a bungalow extension.

Size and complexity of the extension

Every bungalow owner wants something different out of their extension. On the modest end, this could involve a front porch extension or a small side extension. However, grander extension ideas for a bungalow involve large rear extensions, or even a double height extension.

The larger and more complex you make a bungalow extension, the more it will cost to build. 

Remember, you’ll need to add some contingency funding to your project. If your budget is tight, you’ll need to be prepared to scale down your plans if required to keep on track.

Ground conditions and foundations

A bungalow extension relies on the ground conditions to ensure a stable structure can be built on top. 

The ground conditions which can increase the cost of extending a bungalow include:

• Poor soil conditions
• Large trees (existing or removed)
• Sloping ground
• Flood risk area
• Nearby structures

Based on the ground conditions and the scale of the extension plans, foundations will need to be built to support the extension. Strip foundations are the cheapest option, although costly piled foundations may be required if the ground conditions are very poor. 

Choice of roofing

The extended part of your bungalow will require a roof. The main choice to make is a flat or a pitched roof. Either option then has a range of materials which will impact the cost of the job. 

Head over to our roofing section to get free advice or learn more about the costs involved in building or replacing a roof in the UK. 

Flat roof extension on bungalow

A flat roof is always going to be your cheapest option. For a single storey bungalow extension, a flat roof option makes the best sense, unless you will be creating a vaulted ceiling.

The average cost to install a flat roof is £100 to £150 per m².

The material options for a flat roof include felt, EPDM or GRP fibreglass. Just be mindful that flat roofs have a shorter lifespan than pitched roofs, meaning opting for a higher grade material is advisable. 

Alternatively, green roofs are becoming a popular choice for eco-conscious homeowners. The typical price to install a green roof is between £50 to £350 per m².

Pitched roof extension on bungalow

A pitched roof may be necessary to support a double storey extension. It may also be required so that the roof matches the existing bungalow to prevent planning objections. 

The average cost to build a pitched roof is £150 to £250 per m². 

Cheaper materials for a pitched roof include concrete or clay. Natural slate is more expensive, though it offers a traditional finish. 

Contemporary alternatives include zinc roofing, although this material has a higher upfront cost averaging £350 to £400 per m².

Materials and finishes

When purchasing the materials and interior finishes for a bungalow extension, you can choose from off-the-shelf to fully bespoke. 

Items that are of exceptional quality or custom-made will be more expensive than the likes of flat pack furniture, or likewise, any materials that can be purchased cheaply at your local DIY store. 

Just remember that the level of specification will be reflected in the value added to your bungalow. 

Access to the site

In an ideal world, your bungalow will sit on a large plot of land and provide ease of access. This is to allow tradespeople, machinery and materials to get to where they need to be during the extension. 

Access challenges can bump up the cost of a bungalow extension, and even potentially limit the willingness of some trades to take on the job. 

Design and layout changes

To perform a bungalow extension, at least one main wall will need to be altered. But once you start removing internal load-bearing walls or altering the roof structure, additional structural support will be needed. 

That said, if your bungalow currently has a very awkward layout, the extra cost to improve the amount of usable space will be well worth it. 

Planning constraints

Nobody likes being told ‘no’ when submitting plans for an extension. However, reworking your plans so that they get approval can also be costly. That’s because your architect or planning consultant will need to come up with a solution and resubmit your plans. Unless your plans are simplified, any mitigation works will inevitably increase the total cost. 

However, ignoring planning rules is even costlier. It can even result in you needing to demolish your extension (at your own expense) in addition to various financial penalties. So don’t overlook this step! 

Structural alterations

Structural alterations are one of the big cost drivers for bungalow extensions. Even if you’re building a single storey extension, extending often means altering the load bearing structure of the original property. 

Any structural alterations will require structural drawings and calculations to be produced in addition to the structural reinforcement work itself. 

Kitchen or bathroom installations

Bungalow extensions can be used to create a larger kitchen, or add another bathroom. Both of these rooms present a lot of value potential, though can significantly push up the total cost of a bungalow extension. 

Scenarios which mean you’ll pay a higher cost for a kitchen or bathroom when extending a bungalow:

• Opting for a high specification kitchen or bathroom
• Grander plans, i.e. opting for a full bathroom suite rather than a guest WC
• You need to knock through internal walls as well as extend
• There is a long distance from the existing plumbing and drainage, meaning relocation or relocation of pipework is needed
• Mains water upgrades are needed to support the extra demand
• You need a new boiler as your existing boiler wouldn’t be powerful enough to serve an additional bathroom

Energy efficiency features

Make sure your bungalow extension creates a warm and cosy space by investing in its energy efficiency. 

Aspects to consider include wall insulation, roof insulation, insulated floors, high performance double or triple glazing, insulated external doors, underfloor heating, solar panels and smart thermostats. 

Granted, there is an upfront cost to improving the energy efficiency of your property. But, it’s the best way to lower your energy bills over the long term. Plus, any improvement on the EPC of your property can lead to higher resale values. 

Top tip: Extending your bungalow is the perfect time to swap out your old gas boiler for a more efficient model. You may also qualify for £7,500 of BUS funding to help towards the cost of a heat pump.

Labour and professional fees

Tradesperson	Typical day rate
General builder	£150-£250
Labourer	£80-£120
Bricklayer	£180-£250
Carpenter/Joiner	£180-£250
Plumber/heating engineer	£200-£300
Electrician	£200-£300
Plasterer	£150-£200
Roofer	£180-£250
Painter/decorator	£130-£180

A bungalow extension won’t build itself! Unless you’ll be handling any of the work yourself, you will need a variety of tradespeople to do the physical work, plus some experts to guide your plans. 

For a typical single-storey rear bungalow extension (20-25m²), labour alone is usually £15,000 to £25,000, depending on finishes and complexity.

Professional fees

Specialist	Service	Typical cost
Architect	Initial design & measured survey	£1,000-£2,500
Architect	Planning drawings	£1,500-£3,500
Architect	Detailed drawings for building regulations	£1,000-£2,000
Structural engineer	Steel beam calculations	£400-£600 per beam
Structural engineer	Full set of structural drawings for extension	£800-£1,500
Planning consultant	Advice about your extension plans	£100-£150 per hour
Planning consultant	Full planning application & representation	£1,500-£3,000
Planning consultant	Planning appeals	£3,000-£6,000
Building control (local authority)	Extension inspections and approvals	£500-£900
Building control (Private approved inspector)	Extension inspections and approvals	£800-£1,200

Remember, not every bungalow extension will require all of the above. However, you’re more likely to need professional input if your plans fall outside of permitted development rights. 

Other potential fees for a bungalow extension:

Party wall surveyor – If working close to a neighbour’s boundary, you’ll need to hire a party wall surveyor. The cost is around £700 to £1,500 per neighbour. 

Topographical survey – For extremely challenging site conditions, a land survey can cost £400 to £800.

Thames Water customers – If your property falls under the Thames Water catchment area, you must get permission before carrying out construction work on your property. This is called a Thames Water build-over agreement. It applies to rear extensions, or work that will be carried out within 3 metres of a public sewer, or within 1 metre of a public drain. The cost for the agreement ranges between £120 to £520. 

Planning Permission and Building Regulations

We get it, you just want to get building that bungalow extension! But as with all home improvement projects, you’ll need to check what regulations apply in your scenario. 

Do bungalow extensions need planning permission?

Bungalow extensions don’t require planning permission if your plans fall under permitted development rights. To ascertain what you can legally do without planning permission, you’ll need to consult the building control department at your local council, as the rules may vary depending on where you live. 

You will need planning permission to extend a bungalow when: 

• You want to build a two storey extension
• Your bungalow is located in a conservation area or its grade listed
• The extension would be on the front or side of the property, or facing a road
• The extension plans exceed permitted development limits
• The property has had PD rights removed
• Significant alterations will be made to the roof

Permitted development (PD) rights

Modest bungalow extensions can usually be carried out under PD rights.

Generally, planning permission isn’t needed when:

• The extension is single storey
• The extension is under 4 metres in height
• The total extended area is less than 50% of the original land around the house
• It’s a rear extension that will be extended up to 8 metres from the rear wall if detached or 6 metres if attached

Building regulations compliance

Even if a bungalow extension doesn’t need planning permission, it will need to comply with building regulations. This is to ensure the newly extended part of the property is structurally safe, energy-efficient and overall is fit to live in. 

Various aspects of an extension need to comply with building regulations. To summarise, this includes structural safety, fire safety, moisture and damp protection, thermal performance, ventilation, drainage and waste and electrical safety.

Working with an architect or planning consultant

It’s not necessarily a requirement to hire advanced specialists such as architects or planning consultants. For modest and straightforward bungalow extensions which fall within permitted development, a competent builder, structural engineer and building control officer may suffice.  

That said, there are various scenarios where having the right expertise can work to your advantage.

Working with an architect who understands the local planning rules can get your project off to a great start. But, if the design looks contentious or if you live in a conservation area, a planning consultant can strengthen your application. 

When to hire an architect for a bungalow extension:

• You need help solving a specific issue such as improving light, flow or aesthetics
• To work right up to permitted development limits without exceeding them
• Overcoming challenging site conditions such as sloping land, unusual shapes, tight boundaries or access issues 
• When blending old and new styles of design, either to create a seamless look or a deliberate contrast 
• For guidance on maximising the future resale value by appealing to buyers and surveyors with the design choices
  

You might also be interested in: How Much Does an Architect Cost?

When to hire a planning consultant for a bungalow extension:

• Your extension plans have previously been refused
• Your bungalow is located in a conservation area
• If your permitted development rights have been removed
• When neighbour objections have arisen or are likely to arise
• If you want to exceed permitted development rules and will need planning approval 

Timeline: How long does a bungalow extension take?

Bungalow extensions can take 2-6 months to fully complete. 

The quickest bungalow extensions are single storey extensions, especially rear or side extensions. Alternatively, converting your loft space can be done in a similar timeframe. 

As you might expect, adding additional floors, or opting for an ambitious design will add time to the project. Additionally, unexpected hiccups relating to the foundations or anything else critical to the structure of the extension can cause delays. 

Average build duration by type

Bungalow extension type	Average timeframe to complete
Loft conversion with dormer	8-12 weeks
Small single storey side or rear extension (15-25m²)	8-12 weeks
Medium single storey rear extension (25-40m²)	12-16 weeks
Large wraparound extension or a double height extension (40m²+)	16-24 weeks

Design, planning and approval stages

3-6 months of planning are usually needed for a bungalow extension before that spade can hit the ground. 

Initial design & drawings: It can take 2-6 weeks to produce the drawings for an extension. However, if you need to make revisions it will take significantly longer. 

Planning permission: Not all bungalow extensions need planning permission, but if they do it can take 8 weeks for your council to grant permission. Expect to wait longer if your home is listed or in a conservation area. 

Building regulations approval: Your local building control will need to approve your extension plans, which can take 2-8 weeks to sort. Thankfully, this can be arranged at the same time as your other admin requirements.

Selecting contractors: Expect to spend 2-4 weeks collecting quotes from tradespeople. Excessive delays can be experienced when a contractor chooses not to quote the job (and doesn’t tell you), or when they are busy and cannot quote promptly. 

Factors that may delay completion

Fingers crossed, your bungalow extension will be smooth sailing. But, there can be a number of hurdles which can create lengthy delays.

• Planning permission refusal 
• Conversation or listed building restrictions
• Party wall agreements
• Making revisions to architectural drawings
• Building control queries
• Weather conditions
• Ground conditions
• Supply chain delays
• Contractor availability
• Access issues
• Neighbour disputes
• Budget shortfall 

By understanding these risk factors before you go ahead, you’re in the best position to reduce the chances your project will experience the same issues. 

Is it worth extending a bungalow?

Yes! It’s a safe assumption that if you are researching bungalow extensions, then you are unhappy with the existing size or layout of your current bungalow. 

Extending a bungalow can create extra rooms, while also solving layout challenges. But as with any building project, it has to make sense based on the costs and disruption you will experience to get there. 

Cost vs. value added

When deciding whether a bungalow extension is worth it, money will play a huge part in the decision. This is both in terms of the cost of the project, but also the potential value to be gained as a result. 

At WhatPrice, we’ve made it easy to get the answers you are searching for: 

Extension Cost Calculator – Enter more details about your specific extension plans such as the number of floors, the extension size and your location. From there, you’ll see instant cost estimates for your project. 

House Extension Added Value Calculator – Will extending your bungalow give you a healthy profit? Find out now! 

Market appeal and resale value

‘Recently extended’ is a term that is extremely appealing to buyers when used by estate agents to market a property. Simply put, extending suggests your home has had recent work done to it, meaning the new owners don’t need to do anything to make the property move-in ready.

Consider that if the existing layout of your bungalow has obvious flaws, potential buyers will be quick to identify these during viewings. So if you want to maximise the value of your bungalow, extending makes sense. 

Adding extra bedrooms or bathrooms is always wise. However, a rear extension to your bungalow would also create a stunning open plan living space to seamlessly lead into your garden. All of these things can give your property the ‘wow!’ factor, helping to reduce the time on market and also the eventual sale price. 

Alternatives to extending a bungalow  

If the costs and disruption involved in extending your bungalow aren’t worth it, there are other options to consider. 

Loft boarding: Involves laying loft boards over the attic joists to create a raised floor space. Boarding a loft won’t give you additional living space, but it can be used for storage. As one of the cheapest options available, loft boarding can also improve insulation throughout your bungalow. 

Garage conversion: Most UK homeowners don’t use their garage for their intended purpose, instead choosing to park on their driveway. A garage conversion can unlock endless potential, especially when turned into an extra bedroom or home office. The cost to convert a garage averages £10,000 to £20,000, making it cheaper than most extension types.

Interior knock-throughs: Does your bungalow have an awkward layout? A structural engineer can advise you if any walls can be knocked through to provide extra space. 

Build a garden room: Most bungalows sit on a sizable plot of land. Garden rooms can be turned into an office, gym or cinema room. Garden rooms have also become popular solutions when in need of a granny annexe, especially if you have a multi-generational home. 

Move: If you dislike the area you live in, or your extension plans aren’t viable, then moving remains an option to consider. 

Common mistakes to avoid

If this is your first property, you might be unfamiliar with hiring contractors or project managing a build. 

By avoiding these common problems, your bungalow extension is more likely to go off without a hitch. 

Underestimating costs

In recent years, the cost of materials has risen sharply. Therefore, the cost of extending a bungalow in your local area may have increased as a result.

Even if you meticulously track your expenses in a spreadsheet, extensions can have hidden costs to factor in. The best way to prepare is to leave a 10%-20% contingency in your budget. 

If you have a very tight budget for your extension, then you may also need to be prepared to adapt your plans. For instance, reducing the size or complexity of the extension. Likewise, lowering the specification of the interior finishes. 

To avoid having to do this, you could also research alternative ways of funding your extension should your project run into financial difficulty. 

Ignoring planning rules

Planning rules are there for a reason. Not researching the laws or regulations which apply in your scenario can result in high legal bills and even the inability to sell your property down the line.

So before extending your bungalow, check that your plans are legal and fully compliant. 

Hiring reputable tradespeople adds another layer of protection, including when it comes to complying with industry-specific regulations. 

Overdesigning for the area

If you’re not planning on remaining in your bungalow indefinitely, then you’ll likely be motivated by the value to be gained on the property by extending. But what exactly is the value potential here? 

You’ll need to find out by researching the average property values in your area and comparing this to the current valuation of your bungalow. 

Going too high spec is fine if you won’t be moving anytime soon. However, if you will be selling in the near future, there is a real risk that you won’t see a healthy return from what you will spend on extending the bungalow. 

Choosing the wrong contractors

Extending your bungalow should be a positive and hugely rewarding experience. But as with any type of building work, the wrong choice of contractor can be disastrous. 

Take your time to review skilled specialists in your area. Always collect multiple quotes and be sure to research their professional accreditations, experience, reviews and insurance coverage. 

It’s easy to overlook these things, but you need to know you can trust everyone who will be involved in the project. 

Bungalow extension cost FAQs

Still have questions about how much a bungalow extension costs in the UK? We’ve answered some of the top queries below.