How much does an extension cost?

Posted: 23rd December 2022 | Author: Adam Brown | Category: test

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FIGURES CURRENT FOR DECEMBER 2022

How much does an extension cost?

As 2022 draws to a close, it caused a big stir in the cost of living, inflation rate and energy prices. These pressure straight after a Pandemic have been very hard on the cost of building materials - so it is important to have a good ballpark figure in mind when looking to undertake these projects.

The old adage of £1000 per m2 build cost is well and truly out of the window for good! We now need to realign ourselves to be able to have a better estimate of what these building works will entail.

How much does an extension cost per m2?

As is often the question posed to builders merchant and builders, when a customer first decided they would like an extension, they need to have a figure in mind to budget and plan for carrying it out. 

To give an absolute price is impossible due to the sheer number of variations per site, problems that may arise, local authority requests and much more. We can however use round figures to get in the right direction and make sure it is affordable and achievable.

In the current climate (December 2022) the following figures will provide a good rule of thumb:

• Basic build cost for a single-story extension: £2,000 per m2
• Mid-range cost for a single-story extension: £2,400 per m2
• Double storey extension cost: +50% of single story cost
• VAT at the current (December 2022) rate of 20%
• Professional fees (architect, planning, applications, engineer, building regs etc): 15%
• Addition of finished bathroom: £5,000
• Addition of finished kitchen: £10,000

Example Calculations

Single story extension of 3m x 5m:

• Basic build cost: £2000 x 3 x 5 = £30,000
• VAT: £6,000
• Professional fees: £5,400
• Total: £41,400

Double story extension of 3m x 5m:

• Basic build cost: £2000 x 3 x 5 = £30,000
• Second story: £15,000
• VAT: £9,000
• Professional fees: £8,100
• Total: £62,100

Factors not allowed for

When an extension is carried out, it is impossible to say for sure what factors are needed for added consideration on the job. We have not factored this in for obvious reasons, but it would be prudent to think about other aspects before diving in as they may need planning and budgeting for too:

• Opening from old to new: to access your extension, there needs to be an opening to get to it - this may already exist in the form of doors that can be removed, or needs to be thought about. This may include adding lintels or even needing steelwork calculated and fitted if the opening needs to be larger than typical doorway size. This opening work will also need some form of making good or even lead to a renovation of the old space to suit.
• Specialist equipment to your particular job: sometimes specialist lifting, moving or hoisting equipment may be needed which would incur hire fees and access issues. This equipment may need to have temporary access created and repaired if necessary.
• Electrics and plumbing: the estimate allows for the basics of taking some lighting and power to the new space as well as heating pipework; however, if the pipework is complicated or needs re-routing around the property, this would incur extra costs. This is often dependent on where the nearest electrical spurs are of the position of the boiler. There can sometimes be the need to upgrade your fuseboard if your current one is already at maximum capacity before the extension.
• Plus plenty more considerations such as: decorating, access, removal of old space, abnormal ground conditions, insurance and more!

Permitted Development - How far can I build without planning permission?

In the UK, permitted development rights allow you to carry out certain types of work to your property without needing to apply for planning permission. These rights apply to both residential and commercial properties, and the rules vary depending on the type of work you want to do and the location of the property.

For extensions to a dwelling, the size limits for permitted development rights are as follows:

• Single-story extensions to the rear of a property: up to 6 meters for a detached house and up to 4 meters for any other type of dwelling.
• Two-story extensions to the rear of a property: up to 4 meters for a detached house and up to 3 meters for any other type of dwelling.
• Single-story extensions to the side of a property: up to 4 meters for a detached house and up to 3 meters for any other type of dwelling.
• Two-story extensions to the side of a property: not permitted under permitted development rights.

There are also limits on the overall size of the extension relative to the size of the original property. The extension must not extend beyond the rear wall of the original dwelling by more than 50% for a single-story extension or by more than 40% for a two-story extension. Additionally, the extension must not take up more than 50% of the area of land around the original dwelling.

It's important to note that these rules are just the general guidelines for permitted development rights, and there may be other factors that could affect whether your extension is permitted under these rights. For example, if your property is listed, in a conservation area, or is located within certain designated areas, the rules may be different. In these cases, you may need to apply for planning permission even if your extension would normally be allowed under permitted development rights. It's always best to check with your local planning authority to confirm whether you need to apply for planning permission for your extension.

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The Author: Adam Brown

With a background as a Mechanical Engineer, I started Nationwide Supplies alongside my brother with a vision to modernise what seemed a stuck-in-its-ways industry in the builders merchant sector.  Since 2011 it has been my goal to source quality products at the correct prices to be able to offer a saving to customers along with high quality customer service which offers quick delivery and superior technical knowledge in the industry.  

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