5 Ways to Make Sure Your Extension Project Stays on Budget

Ensuring your project stays within budget is arguably the most important factor when embarking on a domestic extension or conversion project. We’ve listed five of our top tips to ensure you don’t over-shoot your build budget.

Our Top 5 Ways to Make Sure Your Extension Project Stays on Budget


  1. Calculate your maximum budget

We have seen numerous examples whereby homeowners see their dream extension in a magazine or on a tv show, get excited, before jumping straight into the deep end and getting proposed plans compiled and submitted for planning.

They then pass the proposed drawings onto builders, who subsequently comes back with quotes that far exceed the homeowner’s expectations, resulting in the project being a non-runner before planning has even been granted.

To prevent this from happening, you need to inform your designer of your budget from the outset, so that they can compile proposals that are capable of being built within that budget.

It is far too easy to get carried away when plotting grand design details down on paper. Yet, the reality is, these will have a knock-on effect on your overall build costs. For example, a large, imposing glass roof lantern will cost significantly more than a traditional mono-pitched timber roof.

  1. Add a contingency

From building control requiring deeper foundations due to poor ground conditions or a change of mind when it comes to the kitchen design, there will always be some un-foreseen changes that will throw your costs out slightly.

We therefore always recommend holding a contingency sum of say 10% of your initial budget, which, if required, can be gradually eaten into as the project progresses across the different trades and work stages.

There is nothing worse than being handed a bill by your builder for additional un-foreseen works, knowing that you don’t have an emergency fund to dip into.

  1. Get a fixed price from your builder

We have seen this on numerous projects in the past; a crafty contractor submits a quote (which is the lowest) and are subsequently awarded the project. About 4-weeks into the job they then turn to the Client and present them with an additional quote for electrical works or bathroom fitting costs, claiming that this did not form part of their original quote.

To avoid this, you need to inform the contractors who are pricing the project, that you require a fixed price for everything, down to the last screw. A competent contractor will also provide a full breakdown within their quote, highlighting each stage of the build, from foundations to plumbing and electrical works.

This will give you the peace of mind that the project costs won’t keep on ticking over as works progress.

  1. Phase the project

Although this isn’t the most ideal situation, if your budget is tight, yet you do not want to compromise when it comes to design, then one option is to split up the project into phases.

For example, the expensive bespoke kitchen or bathroom could wait a few years whilst you get by with the cheaper alternative. Likewise, you could hang back from completing the final fit out of the loft conversion and for the time being use the room for storage.

If you are confident enough, you could get a main contractor in to build the shell of the extension, ensuring it is fully watertight, before managing the fit-out stage yourself, by arranging for individual trades to come in where necessary.

  1. Be decisive!

It’s simple – make up your mind, and stick to it. Variations during the contract period are the main cause of project cost increases.

Contractors need decisions early on, so that they can order the materials and organise the labour to ensure the subject works fit in with the programme. When a client makes significant changes, this messes up the entire programme, creating a longer project duration and thus increasing costs.

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