It’s incredibly easy to blow your budget out of the water when extending your home. Here are a few tips to keep costs under control.

Do you really need an architect?

Most architects don’t charge for initial one-off consultations and they can be incredibly useful. They can give you advice on design, cost, planning and construction. Unless your project is very simple, it makes sense to at least talk to an architect before you start. Typically, architects begin to offer a full service for projects with a budget of £30,000-plus but they can help you get the best out of your new project regardless of size. Look for design professionals with a track record of low-cost extensions. An alternative is to find an architectural technician, chartered surveyor or structural engineer to produce planning and Building Regulations drawings for a fixed, all-in fee. 

Don’t under-budget

Too often, when people start to plan an extension, they make the mistake of thinking they can do a lot more than is possible with the money available. Think about your aims - more space, extra light – and list your priorities. Decide the must-haves as opposed to what would be nice to have. Research the price of big ticket items like fitted kitchens. Many off-the-shelf ranges offer value for money. If your project is proving too costly, it might be best to rethink your plans and design. To figure out a realistic budget, factor in the cost of fixtures and fittings, materials, labour, trades and professional fees, including VAT.

Get realistic quotes from builders.

Beware cowboy builders who vastly under-estimate costs simply to win a job. Get at least three quotes to compare – and never, ever pay for work in advance.  An estimate is just that - an educated and non-binding guess about what a project may cost. Whereas a fixed-price quote is an agreed price based on work shown on a drawing or specification. The more information you can give, the closer the quote will be to the final bill. Ask for a full, written breakdown of the price, so you can see all the costs are included and compare like-with-like. Otherwise you may be hit by big bills for extras not included in the original quote, for example scaffolding. Remember to take up references and ask previous clients if their project was finished on budget.

Stick to the plan

Once building work has started, it can be tempting to keep adding to your extension or change your mind mid-way. For example, you may find yourself standing in your remodelled kitchen and ask the builder to alter the agreed layout which means relocating plumbing and wiring.  If you keep changing your mind or adding to your builder’s to-do list, the additional costs will make the original agreed quote, and therefore your budget, meaningless. If keeping to a budget is top priority, stick to the plan.

Plan for the unexpected

Having said that, it’s good to plan for the unexpected. Sometimes an extension uncovers a maintenance issue, such as leaking roof or outdated electrical wiring which needs fixing.  And sometimes it’s worth the cost of changing your project along the way if it’s going to significantly improve the look or function of your new space, for example a taller ceiling or underfloor heating. It’s a good idea to add 15 to 20 per cent on top of your winning contractor’s bid as a contingency fund.

Act as project manager  

One way to try to stick to the budget is to manage the build yourself, taking on the role of building contractor. This will mean liaising with your local authority’s building control department, structural engineer and architect as well as finding and hiring tradespeople, directing the work and supplying building materials, skips and scaffolding.  It’s time-consuming and can be difficult to juggle with full-time employment. To do it well, you need some knowledge of construction, management skills and time. The project might take longer to finish but savings can be huge. A builder will add 15-25 per cent on the total cost of labour and materials for managing the project.

Reuse old materials

Many extension projects involve knocking down walls before building begins. Reusing the original back doors, bricks or roof tiles if they are in good condition, will not only save you money but help the new addition to blend with the old. Old kitchen cupboards could be spruced-up for a new utility room instead of thrown in the skip. Salvage yards can also be a good source of second-hand items that can be cheaper than buying new, such as timber floorboards, fireplaces and roll-top baths. Your builder may also be able to help, for example with bricks from a demolition project. Second-hand items are free of VAT.

Get stuck into DIY

It’s possible to save hundreds if not thousands by rolling up your sleeves and tackling the simpler jobs. How much you can contribute will depend on your skills and experience. Some jobs are best left to the professionals, such as electrical work and plumbing. Botched DIY can be dangerous and very expensive to repair.  But most people can swing a sledgehammer to demolish an internal wall under supervision of their builder. There may be other jobs you can do, such as painting and tiling.

Bargain hunt

Find out where builders buy their materials and try to get the same wholesale/trade prices. Scour the internet and local suppliers for bargains. Seek out ex-display fittings in showrooms. Try eBay and Freecycle.com for large items. Try to negotiate a discount for buying multiple items from one supplier, such as washing machines, ovens and fridges.  Buying discontinued lines can also save you large sums, for example units, appliances, tiles and carpets.

Plan ahead

Planning ahead for your extension project can really pay dividends. Look for the best bargain buys in the sales and store them in your garage or spare room or with family and friends if you haven’t the space. Don’t wait until just before you need a new kitchen or bathroom or light fittings to search – snapping up a bargain when you see it can result in big savings.

While it takes more effort to stick to a tight budget you can still get a great result – and without breaking the bank!