Home extension- cut-cost ideas | homify

Home extension- cut-cost ideas

Johannes van Graan Johannes van Graan
homify Modern houses
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The wonder of a home extension goes so much deeper than simply adding space to a home; it’s about adding potential and beauty and about the positive changes it means to your household. After all, there is nothing like some extra space (an extra bathroom or guest bedroom, or a bigger kitchen and dining room, etc.) to freshen up your perspective on your house, is there?

But like everything else in life, that new extension comes with a price tag – and if you’re not careful, it could be a painful one.

We here at homify want you to have enough left over to spend on pretty interior touches after the physical extension has been completed. So, to ensure your budget doesn’t get ripped to shreds, read on to find out how you can save money with your extension project.

1. Keep the design simple and straightforward

Big doors out into the garden homify Modern houses

Big doors out into the garden


A simple rectangular or square footprint with a straightforward pitched roof will be the cheapest build, and curves and corners are more costly. 

In addition, avoid products that have to be made to order – rather opt for materials that are readily available and easy to use. Stick to cast concrete for the sub-floor; concrete blockwork for the walls; brick, render or timber cladding; and a softwood timber roof structure.

2. DIY can save you even more

Labouring, decorating and landscaping are some of the easiest tasks to take on, followed by some of the ‘second fix’ trades like kitchen and bathroom fitting, tiling and fixing architraves, coving and skirting boards.

However, be very careful before you jump head-first into a DIY project – you will need the required time and skills to complete the job effectively. And remember that poor workmanship always shows!

3. Project-manage the extension

Want to cut between 15 and 25% of the total cost of labour? Appoint yourself building contractor, but make sure you do a good job! 

This will mean liaising with your designer/architect and your local authority’s building control department, finding and hiring tradespeople, directing the work and supplying all of the necessary materials, etc.

4. Save on VAT

Dukes Avenue Coupdeville

Dukes Avenue


Most extension work will attract VAT at 20% on labour and materials. However, using self-employed tradespeople who each turn over less than the threshold for VAT registration will cut out this cost. 

Remember that second-hand materials sold by private individuals online will also be free of VAT.

5. Keep your neighbours informed

If that extension is being built on or near the boundary of a neighbour, the project will need to comply with the Party Wall Act (England & Wales) 1996. If a party wall settlement is required, it will cost around £700 per neighbour; more if they use their own independent surveyors.

You need to notify your neighbours in writing about your extension plans eight weeks before you start. If you can manage to have them write back that they do not object, you can avoid using a surveyor to arrange a party wall settlement and, thus, save on fees.

6. Save on design costs

Rear elevation showing timber extension Neil Dusheiko Architects Modern houses
Neil Dusheiko Architects

Rear elevation showing timber extension

Neil Dusheiko Architects

Certain designers know how to keep the costs down, while others are quite skilled at producing complicated (yet beautiful) plans that cost a pretty penny. 

For a simple, low-cost build, find an architect (or architectural technician, chartered surveyor or structural engineer) who will produce planning and Building Regulations drawings for a fixed, all-in price. 

Look for a track record in designing low-cost projects.

7. Avoid the swindlers

Rear view of the new single storey extension ArchitectureLIVE Modern houses White

Rear view of the new single storey extension


As in any trade, the building profession also has its fair share of cowboys – those that, through incompetence or deliberately to secure a job, underestimate costs and then ask for more money for changes or ‘extras’. 

Always ask for references before you hire anybody – and be sure to check them. Never pay for building work in advance; pay only for work that has been completed to your satisfaction.

8. Measure twice, but cut once

Measuring everything onsite (rather than off your plans) will help reduce wastage. And remember that the more time spent at the design stage, visualising the end result, the more problems can be anticipated and headed off. 

An accurate and complete design will ensure that you have services (such as plumbing and wiring) in the right places, get the correct floor levels, and that doors are hung to swing in the most space-efficient direction.

Once you’ve decided on a design, stick to it. Changes always incur extra costs.

9. Reuse, recycle and repair

Existing materials, such as old floorboards, doors or radiators, can all be revived and reused, cleaned up and given a new finish. Rather sell or trade what you can’t use instead of throwing it out. 

In addition, buying salvaged materials (either online or from salvage yards) can be a lot cheaper than buying new.

10. Negotiate discounts

New life for a 1920s home - extension and full renovation, Thames Ditton, Surrey TOTUS Modern kitchen

New life for a 1920s home—extension and full renovation, Thames Ditton, Surrey


Always be on the hunt for a discount. Find out where those in the trade buy their materials and aim to get the same wholesale/trade prices. 

Bulk-buy from a single supplier for a further discount and ask about reduced delivery costs. Jumping on end-of-line deals will save you a fortune, especially on items such as carpets, units and appliances.

Sometimes the best deal means moving away from big brand names. However, you can still manage to save on price without compromising quality. Shop around and be sure to compare both price and class. 

For some inspiration, let’s take a look at: 18 house improving extensions (you can actually afford).

What else can make a dent in extension project costs?

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