How much does a brick-built extension cost?

A brick-built extension is a good idea if you are thinking of adding extra room to your home. A lot of homeowners ask how much does a brick-built extension cost in 2025? In this blog post we can look at costs and different aspects to take into consideration.   

Cost of a brick-built extension 

The cost of a brick-built extension depends on the materials used and the overall size. 

1. Single story extension costs –

A brick-built single-story shell will cost between £37,500 and £42,500 dependant on size. You must be aware that this is the cost of the groundwork and shell only. Additional costs are required to fully fit out such as a fully fitted kitchen, flooring and plastering, electrics. heating etc. Another way to guide you through budgeting is to allow £2,700-£3,000 per square metre for the completed shell and your local authority building control fees and planning permission fees. There will be a cost of approximately £1,500 for architect’s fees. 

2. Double story extension costs –

A double story brick-built extension will cost between £72,500 to £125,000 dependant on size. This only creates the shell, with additional expenses required for the internal such as flooring, electric’s, plastering, heating and internal fit out. Another way to guide you through budgeting is to allow £2,200 per square metre for the completed shell and your local authority building control fees and planning permission fees. There will be a cost of approximately £2,500 for architect’s fees. 

When choosing an extension, you must think about the different factors that will affect the overall cost. The size of the extension will change the price. The type of materials used will influence the overall cost depending on whether you choose to pay for higher quality materials fittings etc. Certain features such as insulation and glazing can have an impact. You will also need to obtain planning permission before you have an extension fitted, making sure you comply with the building regulations. The cost of labour can vary depending on the contractors you choose to carry out the work. Consumer Advisory will put you in contact with approved and accredited contractors that specialise in building extensions. This is covered under our section of general builders. 

Advice on planning permission  

Before going ahead with building your brick-built home extension you need to obtain planning permission. To get planning permission you to consider and carry out the following: 

1. Check with your local planning authority –

There are different rules and regulations regarding building extensions depending on the area you live in. Contact your local council and check if you need planning permission for your extension. 

2. Think about permitted development –

Smaller extensions could qualify for permitted development; this means you don’t need formal planning permission. Examples include: 

• A single-story extension could be permitted if it no more than four metres high. 

• It is up to six metres in size  

3. Consult a professional 

A good option is to get advice from an architect or designer who specialise in ensuring your designs meet the correct local authority guidelines.  

Factors to be aware of  

There are certain rules and regulations that you need to be aware of which include: 

• Materials used on exterior work must be like the appearance of the exterior on your existing house.  

• If you live in a listed building, you will need listed building consent.  

•  There are usually more restrictive policies for building in the countryside.  

• If you build the extension without planning permission, you can be served an enforcement notice to have the extension removed.  

For further information and guidance please visit Planning permission: When you need it – GOV.UK  and Planning Portal 

Conservatory or Extension: Which is Best? 

There are different advantages when it comes to a brick-built extension and a conservatory. A brick-built extension gives a permanent living space while a conservatory gives a bright area to your home. Adding conservatory roof insulation panels can make conservatories equal to extensions in terms of energy efficiency and keeping the temperature regulated.  

Planning your project – Whether you decide on a brick-built extension or a conservatory you need to consider the following steps when planning: 

• Budget- First you need to decide on how much you are willing to spend in total 

• Design- Have a think about the layout, size and materials used 

• Professionals- We think it is best to hire professionals, consumer advisory can put you directly in touch with accredited professionals. 

• Permissions- It is important that you obtain planning permission and the necessary approvals.  

• Insulation- Have a think about the most suitable insulation method for your conservatory or extension.  

Insulation in extensions and conservatories  

Having the correct insulation fitted in your conservatory or home extension is important. When considering extensions people ask how do you insulate a conservatory roof? 

How to Insulate a Conservatory Roof? 

There are different methods and options to choose from when deciding how to insulate your conservatory roof.  

• Insulated conservatory roof panels – These are often made from lightweight aluminium, packed with insulation. The panels prevent heat from the sun entering the conservatory in the hotter months and traps heat in during the colder months.  

• Solid roof – Older Conservatory roofs can create the effect of a greenhouse in the hotter months, making it too hot and uncomfortable. By replacing your existing roof with a solid roof, it can help to keep the temperature regulated throughout the year.  

• Thermal inserts – These can help your conservatory roof from being discoloured and can protect your furniture from ultraviolet rays.  

• Aluminium foil thermal wadding systems- This provides an excellent thermal performance for your conservatory roof. It prevents heat loss in the winter months and keeps he conservatory cooler in the summer months.   

• Thermal blinds or curtains- These are a good option if you have a lower budget. They can also help reduce the noise from outside.  

How Much Does It Cost to Insulate a Conservatory Roof? 

When choosing an option to insulate your conservatory roof you need to think about your overall budget. There are different methods including:

• Aluminium foil and thermal wadding system – Costs range between £3,500 to £7,000. 

• Thermal inserts or panels – Costs range between £4,500 to £9,000. 

• Solid roof replacement – Costs range between £9,500 to £20,000. 

Conclusion  

In our opinion a brick-built extension or a conservatory with an insulated conservatory roof is a perfect option for adding extra space and value to your home. It is an important decision to make whether you want a single-story brick-built extension costing between £37,500 and £42,500 or a double story extension costing between £72,500 and £125,000.  

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