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Estimated Cost of House Extension

What will an extension cost in 2023?

What does a house extension cost? If you’re planning to expand your house, check out our guide to find out what it will cost. We’ll walk you through the costs of labour, material and other charges which could be charged.


What will an extension cost in 2023?

What does a house extension cost? If you’re planning to expand your house, check out our guide to find out what it will cost. We’ll walk you through the costs of labour, material and other charges which could be charged.

How Much Does an Extension Cost?

Let’s go straight to the main…

The typical cost for extending your home is about £15,000-£125,000.

That’s quite a wide price, but let’s clarify:

The price of an extension will depend on the kind of extension you want to get, its size along with the grade of its finish.

For example, a one-storey extension will cost you between the range of £15,000-£100,000. The type of extension you see is typically used for smaller expansions, such as an addition to a bathroom, or for adding space to the kitchen or living space.

This is still a large cost but let’s dissect it a little more.

A modest single-storey extension (15m2) will have an average cost of between £15,000 to £30,000. The price range is mostly influenced in the high-end of the finish and the location.

The cost of a massive single-storey extension (50m2) could cost anything between £50,000 and £100,000.

It is also possible to have an extension that doubles. This has two floors that allow you to increase the size of your home in both the upstairs and downstairs of your house. The price for a double expansion can range from around £40,000 to about £200,000.

As you will notice, it’s hard to establish a reasonable cost range for extensions to your home.

House Extension Cost

Want to know the costs of adding an extension to your house in more specific terms?

Let’s take it apart a bit.

Cost of Single-Storey Extension

Single-story extensions are an extremely popular home extension that is usually employed to improve the space of a living or kitchen room located on the top floor of a home.

The price of an extension of one storey is approximately between £1400 and £2000..

The table below lists the cost of a single-storey extension for various dimensions of basic quality, average, and premium good-quality constructions.

Size (m²)BasicAveragePremium
Small (15m²)£21,000£26,000£30,000
Medium (25m²)£35,000£43,000£50,000
Large (50m²)£70,000£85,000£100,000

Double Storey Extension Cost

A double-storey extension can be built on two floors in a house to provide more space to your family members by permitting you to build several rooms.

The price of an extension that has two floors can range from £1400-£2000 per square meter.

The table below outlines the cost for different dimensions and types of double-storey extensions.

Size (m2)BasicAveragePremium
Small (30m2)£42,000£51,000£80,000
Medium (60m2)£84,000£102,000£120,000
Large (100m2)£140,000£170,000£200,000

Rear Extension Cost

An extension for the rear is constructed on the rear of a home with a huge space for a garden.

The price of an extension to the rear is about £1000 or £1600 per square meter.

The table below outlines the costs for various-sized standard, average, and premium rear extensions.

Size (m2)BasicAveragePremium
Small (15m2)£15,000£21,000£24,000
Medium (25m2)£25,000£35,000£40,000
Large (50m2)£50,000£70,000£80,000

Cost of Side Extension

The side extensions can be a common option for homes that have plenty of space to the right or left hand sides of the house.

Typically, side extensions are priced approximately £1000 or £2000 per square meter.

The table below illustrates the different sizes of constructions for basic or average and premium side extensions.

Size (m2)BasicAveragePremium
Small (20m2)£20,000£30,000£40,000
Medium (40m2)£40,000£60,000£80,000
Large (60m2)£60,000£90,000£120,000

Cost of Side-return Extension

Properties that have a little space on the back of their house that is used for storage of bikes, bins and so on could be able to benefit from an extension of the side return.

The cost of a side return extension in square metres is approximately £1500-£2400.

The table below outlines the various costs associated with basic or average and premium side-return extensions.

Size (m2)BasicAveragePremium
Small (6m2)£9000£12,000£14,400
Medium (9m2)£13,500£18,000£21,600
Large (12m2)£18,000£24,000£28,800

Kitchen Extension Cost

Are you looking to build a bigger kitchen at home?

It is a good idea to build an extension for your kitchen.

The cost would be about the same amount as a single-storey extension, ranging from £1400-£2000 per square meter, and £200-£1000 per square metre for the kitchen installation.

The table below lists the cost of small, medium and large kitchen extensions for different budgets.

Size (m2)BasicAveragePremium
Small kitchen extension (6m2)£9,600£13,800£18,000
Medium kitchen extension (9m2)£14,400£20,700£27,000
Large kitchen extension (18m2)£28,800£41,400£54,000
Small kitchen suite (6m2)£1200£3600£6000
Medium-sized kitchen suite (9m2)£1800£5400£9000
Large kitchen suite (18m2)£3600£11,800£18,000

Bathroom Extension Cost

A bathroom extension is perfect for those who have only one bathroom in your home or you wish to expand your bathroom.

The price of home extension with bathrooms is calculated based on the price of single-storey extensions. It will cost around £1400 or £2000 per square metre, in addition to the price for bathroom installation, that is between £500 or £1000 per square meter.

The table below outlines the cost of installing various-sized bathroom extensions of different qualities.

Size (m2)BasicAveragePremium
Bathroom extension for small bathroom (3m2)£5700£7400£9000
Extension of the bathroom to medium size (6m2)£11,400£14,700£18,000
Bathroom extension of a large size (9m2)£17,100£22,100£27,000
Bathroom suite small (3m2)£1500£2300£3000
Bathroom suite of medium size (6m2)£3000£4500£6000
Bathroom suite large (9m2)£4500£6800£9000

Porch Extension Cost

An extension to your porch is a fantastic method to increase the value of the front of your house.

On the average porch extensions can cost anywhere from £500 or £800 per square meter.

The table below highlights costs for uPVC aluminum, wood and brick porch extensions.

Size (m2)uPVCWoodAluminiumBrick
Small extension to the porch (3m2)£2400£1500£2300£2300
Extension to the medium size porch (6m2)£4800£3000£4500£4500
Extension of the porch (9m2)£7200£4500£6800££6800

Prefab Extension Cost

Do you have the verge of a budget crunch?

If you don’t have an enormous budget, an extension that is prefabricated could be the best choice – since it saves labour costs because of it being built prior to the installation.

The typical cost for a prefab extension ranges from £1200 – £1700 per square meter.

The table below outlines the cost for basic as well as premium prefab extensions.

Size (m2)BasicAveragePremium
Small prefab extension (15m2)£18,000£21,800£25,500
Medium prefab extension (25m2)£30,000£36,300£42,500
Large prefab extension (35m2)£42,000£50,800£59,500

Wrap-around Extension Cost

A wrap-around extension is among the most extensive types of extensions that are usually located on the rear side of the house.

The cost per square meter of an extension wrap-around is the range of £2000-£3000.

The table below shows costs of various wrap-around extensions based on an average, basic budget, and premium.

Size (m2)BasicAveragePremium
A small wraparound extension (20m2)£40,000£50,000£60,000
Medium wrap-around extension (40m2)£80,000£100,000£120,000
Large wrap-around extension (60m2)£120,000£150,000£180,000

What are the additional expenses of Extensions?

What are other costs you might have to think about in building an extension?

Let’s get started now.

Extension Costs for Architects

It is worth employing an architect to plan and design your extension and also ensure that it is built to the required standards.

The cost of hiring an architect can range from £18 to £30 per hour.

Extensive Extension Groundwork Fees

When making an extension, it’s crucial that the ground is ready.

This will make sure that the extension is placed on a solid base, and also prevent problems that could arise in the future.

If the ground that is in place is not level, it might require excavating. This could cost anywhere from £30 or £50 per cubic millimetre.

Another important type of groundwork is the installation of drainage. This could mean removing old pipes and installing new pipework as well as drains to make sure that the new extension has adequate drainage.

The cost for installing new drainage can range from the range of £700-£1000.

Extension Costs of Planning Permission

Prior to creating an extension, it’s crucial that your plans are in line with the planning permission requirements. This will prevent you from having to pay around £200 to apply.

To avoid paying for additional costs You’ll have to ensure that your extension is in line with the following requirements:

  • The extension shouldn’t cover more than half of the land on which the property is located.
  • It is not allowed to exceed the top of the roof of the current property.
  • Extensions less than two metres from the property’s boundary should not have eaves greater than three metres in height.
  • The work cannot include the installation of elevated platforms, balconies or raised platforms chimney vent pipes, flues or any other work on the roof (including the installation of cladding).
  • Side extensions have to be one-storey and must not exceed four metres from the elevation on the side.
  • Extensions to the sides of a house cannot exceed half the size of the structure.
  • Single-storey rear extensions should not exceed an additional four meters beyond the wall at the rear of a detached house or three metres in the case of any other.
  • Double-storey extensions should not exceed four metres beyond the rear wall. They also cannot be located within seven metres of the property line.
  • The pitch of the roof of a double-storey extension should match that of the house as closely as is possible.
  • All windows on the upper level of a double-storey extension should be obscured glazed if they are located on the side elevation.

Costs of Extension Building Regulations

Most extensions to houses will require permission from the building regulation before they are built.

What’s the price?

The cost for building regulations approval is different in accordance with your local council. All municipal authorities have different fees in order to obtain building approval.

There are many components of an extension which require the approval of an expert to declare the home safe.

This includes:

  • Walls, both external and internal

Certain extensions require walls to be constructed at or at a lower level than the ground in order to ensure that the structure (the extension) is properly supported.
The walls that are being constructed will form the substructure that typically includes blocks, mortar or brick. In order to ensure the entire structure is safe it is crucial that the structure is impervious to frost and substrates that can be found in the soil.

  • Flooring

In order to ensure that the flooring you have installed in your extension is compliant with requirements for building, it’s crucial that it has a solid structure that can be able to support a substantial volume of load.
It must also be resistant to heat and moisture to allow for insulation, ventilation and protect the flooring from weed growth, dampness and expansion.

  • Ventilation

One of the main aspects to take into consideration when installing an extension is the ventilation. This can improve the quality of air in your home and improve overall health.
For your home to be ventilated you can simply put in windows, especially in areas that aren’t ventilated, such as bathrooms. It is also possible to install trickle ventilation throughout the areas of your house by attaching it to windows frames.

  • Foundations

Before building an extension it is essential that the foundations are strong in place (which are typically made from concrete).
The soil that is used must be strong enough to support all the load of foundations as well as the extension structure. It must be drilled to a sufficient depth to ensure that any movement or contraction does not impact the extension. This is particularly important in the case of a double-storey expansion because foundations and soils will be required to accommodate an extended structure.

What are the supplies costs associated with an Extension?

Are you thinking of an extension that you can make yourself? Perhaps you’d like to get the tools for yourself?

In this instance you’ll have to think about the following costs for supplies:

Description of the supplyAverage cost of supply
Skirting boardBetween  £2 and £8 per M2
PlasterboardBetween £3 and  £16, per M2
Wood flooring£35- £90 /m2
Laminate flooring£7 to £26 for m2
Wall tiles£9 to £45 for M2
Floor tiles£12-£50 per m2
Paint£3 up to £20 per Liter
Plug socketsFrom £2 up to £120 for each socket.
Light switchesFrom £1 to £200, per switch.
Radiators£14 to £400
Underfloor heating£60 to £100 for M2
Doors that are internal£70 to £500
Doors to the outside£35 to £900
Windows£100 to £320
Door handles£3 to £220
Light fittings£2 to £80 for each light

The Tradesmen Costs for an Extension

Another important point.

In determining the price of your home extension, you’ll have to take into account the labour costs that are incurred by the various tradespeople involved in the construction of your home extension.

Let’s look them over now.

Extension Builder Cost

Builders are an extremely crucial task when it comes to building an extension.

They’re also involved in the building of the foundations and also the design of the extensions, to make sure that it’s sturdy and secure.

The typical cost for hiring an architect for your home extension ranges from £130 to £260 per day, or the equivalent of £10 to £15 for an hour.

Extension Plumber Cost

If you are building an extension for your bathroom or kitchen it is necessary to employ a licensed plumber to put in plumbing fixtures, sinks, toilets and much more.

Plumbers can cost anywhere from £200 or £400 each day to install complete bathroom installations. £30 or £60 per hour for the time it takes to play the sink.

Extension Electrician Cost

In order to have your extension fitted with electrical and lighting it is necessary to engage a professional electrician to ensure that everything is safe and operating correctly.

The typical hourly rate for electricians is approximately £30 up to £60 per hour, or £170 to £340 in a single day.

Extension Plasterer Cost

For preparing your walls and to ensure that wallpaper or paint is durable, you’ll require the help of a professional.

Expect paying £150 up to £220 per day to a tradesman to put up your extension. They could be charged an hourly rate of £10 and £20 to replaster the walls.

Extension Painter and Decorator Price

After the plastering has been completed then you’ll need to get an interior decorator to wallpaper or paint the exterior and interior walls of the new house extension.

A common tradesperson would cost between £15 or £40 per hour for painting the walls of one or two.

For rooms with multiple rooms, you can be prepared to pay £100 to £300 per day.

Extension Carpenter Cost

If you’re installing a brand new extension, you must engage a professional carpenter to assist in the building and the installation of your new extension.

A carpenter will cost between £160 to £240 per day.

It is also possible to engage them for small jobs for example, the installation of a new frame for your door. In such a case they’ll generally cost you an hourly rate that ranges from £20 or £40 for an hour.

Extension Kitchen Fitter Cost

If you are planning to build a new kitchen, think about hiring a kitchen fitting professional who will put in the cabinets in your kitchen and also worktops.

For kitchens with small spaces, you’ll need to pay an hourly rate of between £10 and £20 for a larger kitchen, you could be subject to a daily cost of between £120 and £200.

Extension Window Fitter Price

After your extension has been constructed and you are ready to move in an expert window installer to put in windows that are completely insulated.

For a window of one or two You should be prepared to pay anywhere from £8 up to £20 for an hour.

To get a full set of windows with an extension with two floors it’s likely that you’ll get charged anywhere in the range of £100 or £200 each day.

Extension Labourer Cost

Another tradesperson you might require is a labourer. He can assist in the majority of tasks on the job site such as foundations construction as well as the extension structure and much more.

The typical daytime cost for labourers will be £100 to £160 in a day, that is £7 or £15 for an hour.

Cost of Extension Bricklayer

In order to ensure that your extension is built correctly it is essential to hire bricklayers with experience who are knowledgeable about their work.

Bricklayers usually charge between £130 to £180 per day for large extensions or between £12 and £20 per hour for porch extensions.

How long does it take to construct an Extension?

Extensions are a long process that can take a lot of time.

This is why it’s crucial to understand the duration of time required to build the extension you’re planning to build.

Here’s a quick break down:

Extension typeDuration
Single-storey extensionBetween 2 and 3 months
Double-storey extensionFrom 4 to 6 Months
Side extensionFrom 2 – 3 months
Side return extensionBetween 1 and 2 months
Extension of the rearFrom 2 to 4 Months
Wrap-around extensionFrom 4 to 6 Months
Kitchen extensionBetween 2 and 6 months
Bathroom extensionFrom 2 to 4 Months
Prefab extensionFrom 8 to 10 weeks
Extension of the PorchBetween 3 and 14 days

What is the cost for each stage in an Extension Price?

There are several stages when building an extension

Each of these stages comes with distinct costs that you have to be aware of (and plan for).

Let’s take a look now.

Building Regulations and Design

So, what’s first?

It is essential to begin by checking that the extension’s design is in line with the current building regulations and building permission regulations.

What happens if your current plans don’t conform to the rules?

If that happens you’ll have to modify your plan or pay £200 or more to have your extension granted.

If you have received approval Once you have received approval, you can begin planning your extension in greater detail.

In order to accomplish this, you’ll need the assistance of an architect. Their primary job is to create plans for the structure that include the dimensions as well as the design of the extension. They also make sure that they follow the guidelines.

Typically, an architect charges between £18 to £30 per hour.

Foundations and Groundworks

Before any building project can be started it is essential that the foundation is ready.

It can be an expensive procedure due to the fact that it requires excavation. It can cost anywhere up to £30 up to £50 per cubic meter, and the final cost is contingent on the dimensions of the area the project is taking place on.

It is also possible to take out pipework and set up new drainage. This will ensure your extension is safe from damage and flooding as well as ensuring that water flows are running and is connected to the principal property (if it requires). The cost of this work is usually from £700 or £10.000.

When all the groundwork is done?

The foundations must be set up to create solid foundations to install the extension. The process of installing foundations is a long-lasting part of the project and can cost anywhere from £100 up to £130 for each cubic metre.

The construction of the Outer Shell

After everything is ready and the foundations are set in place What’s next?

The next step is to construct the walls and frames by using bricks, wood blocks, tiles and materials.

The price for the extension shell ranges from about £800 up to £900 per square centimetre. This is for experts to construct an extension shell that is weatherproof.

Fixtures and fittings

The final step is about final details.

This includes the installation of furnishings (like countertops and kitchen cabinetry) that will cost between £1000 to £7000.

To get a bathroom extension it is recommended to shell out between £1400 up to £6000 for new fixtures for your bathroom.

In this phase at this point, your windows and doors are also going to be put up. It will cost you approximately £400 to £600 per window, whereas door installation typically costs between £40 up to £90 for each door.

It is also recommended to install outdoor and indoor lighting fixtures at this point. This typically ranges from £60 to £1000 If installed by an electrician who is a professional.

How Much Does an Extension Roof Cost?

The most crucial aspects of a home extension includes the roofing.

There are several kinds of roofs you can pick from.

Let’s take a look now.

Dual-pitched Extension Roof Cost

The duo-pitch or a gabled roof (or the gabled roof) is a basic roof design that features two slopes that meet at an incline.

Duo-pitch extension roofs are typically priced from £3000 up to £4500.

The Flat Extension Roof Cost

Flat roofs are a kind of roof that’s almost completely flat with only an occasional slope, which allows drainage.

An extension that is flat usually costs around £1200 up to £2000.

Catslide extension roof Cost

A cat slide roof is a form of pitched roof that slopes down more from one end than on the other.

The cost of an awning with a slide slide ranges from £1000 up to £1500 per square meter.

Cost of Mono-pitch Roof Extension Cost

A mono-pitch or Lean-to roofing is a single sloped roof. This is one of the cheapest roofing solutions.

The price of a construction for the mono-pitch extension roof ranges generally somewhere between £2000 or £3200.

The cost of a Hipped Roof Extension

A hipped roof is made up of four sides that slope upwards. They all are of equal length and join at the crest’s central point.

The price for an extension roof that is hipped typically ranges from the range of £4000-£4500.

Cost of removing an Extension

What happens if you wish to take off an extension that was in use for a while? What should it cost you?

To ensure that the extension removed correctly, you must think about hiring a professional. The cost will range from £500 up to £3000.

To top it all off to this, the price of the removal of waste will be in the range of £70 to £300.



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