​"How do I accurately cost out my kitchen extension?" | homify

How do I accurately cost out my kitchen extension?

Johannes van Graan Johannes van Graan
homify Modern windows & doors
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We all love the idea of extending the heart of the home, as it could finally mean some decent socialising while cooking! In addition, such a home improvement project will definitely increase your home’s value – a significant factor if you plan on selling later down the line.

Yes, a kitchen extension is definitely one of the most desirable improvements to add to a home – unfortunately, it turns out that this genius idea is also one of the most expensive to undertake. And be honest: how many of us have any real concrete ideas about budgets when it comes to enlarging a kitchen? 

But don’t let your hopes for a culinary dream space evaporate, for today we take a look at a detailed run-through of the relevant costs that go hand in hand with a typical kitchen extension.

Let’s start at the building work…

1. The building work

Kitchen Extension with Bi Folding Doors homify Modern windows & doors

Kitchen Extension with Bi Folding Doors


So, how much do you need to set aside for the physical building of your dream kitchen? We recommend around £1,500 per m², although higher-specification finishes can increase costs up to £3,000 per m² (plus £1,400 to £1,800 per metre if you plan on including bi-fold doors). 

Bear in mind that difficult ground conditions, such as clay, peat, nearby trees or slopes, will increase foundation costs. Therefore, ask a professional structural engineer and your local authority building control for an idea of the type of foundation on your property.

2. The kitchen design

Although figures from £17 per m² to £144 per m² are viable, the costs will rise if you opt for a specially-made kitchen.  

The design costs can either be included in what you spend on the kitchen itself, or reflected in your total architectural fees.

3. The professional fees

• Design fees for a kitchen extension will range between 3 – 7% of the overall build cost, with a minimum of around £2,400 to £3,600 for the plan drawings. 

• Depending on the size of your property, £500 to £1,500 will be required for a measured survey of your house.   

• The fee for construction drawings that are sufficient to build from (and for building regulations approval) will typically cost the same as plan drawings, with a minimum of £2,400 to £3,600. 

• Structural engineer’s fees will range from £500 to £1,000. These are vital to design the foundations, roof, any large span openings and structural alterations to the existing house.

4. Planning application

Private House - Holland Park New Images Architects Modern balcony, veranda & terrace
New Images Architects

Private House—Holland Park

New Images Architects

For a householder planning application, the fee is currently £172 in England, £192 in Scotland, £166 in Wales and £285 in Northern Ireland (NI). 

In England, a certificate of lawful development costs £86. Ask your local authority if you’re based in Scotland, Wales or NI. Should your extension require planning permission, you may need the following additional reports: 

• A tree report if your project affects trees: from £720 upwards. 

• A flood risk assessment if your home is within a flood zone: from £720 upwards. 

• Many local authorities require an ecology report: from £720 upwards. 

• An archaeological report based on a watching brief during excavation if implemented in areas of archaeological interest: this can cost several thousand pounds. 

• If your home is listed, a historic building report is likely to be required.

5. Kitchen extension design details: lighting

For a professional lighting designer to add the necessary illumination (to operate ambient, accent and task lighting on different circuits, for control of zones and the freedom to alter the mood, etc.), expect to pay approximately £102 per hour’s consultation.

6. Kitchen extension design details: concrete flooring

When it comes to trendy and hardwearing flooring materials, polished concrete is a fantastic choice. It can be laid both internally and externally, giving visual impact to both spaces. 

Expect to pay from £120 to £144 per m² for a 50 m² / 10 cm-thick floor.

7. Kitchen extension design details: designer tiles

Brick Tile Series Tileflair Country style walls & floors

Brick Tile Series


Tiles are an excellent way to make a statement, with multiple options to adorn your flooring (from rustic terracotta to hand-poured encaustic tiles).

General prices for reclaimed tiles can start from about £72 per m².

8. Kitchen extension design details: building control

The size of your planned extension will affect the fees for building regulations approval. However, they are likely to range from £250 for a project of 1—10 m² and £900 for 80—100 m².

9. Kitchen extension design details: party walls

inside/outside TAS Architects Minimalist windows & doors
TAS Architects


TAS Architects

If your neighbour formally consents to your project, you can avoid a party wall settlement. 

However, should you require them, a chartered surveyor can arrange party wall agreements for you, which will typically cost from £700 to £1,000 per neighbour.

10. Kitchen extension design details: heating

You might be very proud of your new energy-efficient boiler, but you need to check whether it’s powerful enough to handle the additional heating demand. If your boiler is older than 10 years, consider replacing it, as a more energy-efficient design will help offset the cost.

According to the Energy Saving Trust, a straightforward gas boiler replacement will typically cost around £2,300.

11. Kitchen extension design details: decorating

This is where you can significantly reduce costs, as decorating presents many easy DIY tasks. Skilled decorators tend to spend more time prepping than painting, which makes all the difference to the finish. If you plan to decorate, don’t cut any corners on sanding, filling, priming and undercoating.  

Tiling is a skilled profession and, given the high costs of tiles, is not something just anyone should try out on a DIY basis. Ensure you have the proper skill, time and a good-quality tile cutter. 

Second-fix carpentry is another area where a skilled DIYer can shine. Tasks like laying wooden flooring, hanging doors and fitting cabinetry are achievable for those who know how, yet fitting worktops requires more skill and the correct tools for cutting out sinks.

Wall finishes and painting, including minimal tiling, can cost from around £77 per m². The budget for flooring, laid, is usually around £24 to £52 per m².

Now, how about some design inspiration? We recommend these: 5 really handy organisation ideas for your kitchen.

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