Common home extension mistakes

Building an extension on your property can be an exciting experience, unleashing a world of new potential and opportunity for your home. However, there are many potential pitfalls and mistakes throughout the complex process, especially for first-timers.

Our Expert Guide on Common Mistakes to Avoid When Planning and Building an Extension

Failing to plan the extension in full detail

A key element in the initial phase of the process, which can help to make other aspects run much smoother, is having fully detailed plans of the extension drawn up in advance. It’s key to include as much detail as possible at this stage as every length, width and depth leaves less up to interpretation, allowing you to communicate your vision and expectations to your builders.

Having clear, thoroughly thought-out plans from the get-go leaves much less room for unknowns, which in turn, leads to more accurate budget planning, more efficient scheduling, and overall smoother sailing throughout the project.

Poorly planning costs and budget

It is important that you thoroughly consider the costs for every element of your extension and be realistic about what you can afford. Sacrifices may need to be made to meet your budget, but it is critical to plan this before work begins.

Providing builders with thorough plans upfront will help with accurate estimations, however, when issues inevitably arise throughout the process, there needs to be room within your budget to solve them. Be honest with yourself in the planning phase and ensure you are in a position to cover any unexpected costs as they come up, otherwise, you could be looking at long delays.

Do not get lured in by the builder with the cheapest estimate, make sure you are choosing quality work that won’t bring you lots of costly problems moving forward.

Neglecting to research permissions and regulations

You mustn't presume your extension will fall under permitted development rights and that you look carefully at the rules and regulations to find out if you need to apply for planning permission. Factors such as if your property has been extended previously, as well as the size and location of the extension, may affect whether your extension plans fall under permitted development.

If you do decide to build under permitted development, there are strict guidelines that your extension must follow, including size, shape, location, and materials. If these restrictions prevent you from building your dream extension, then it may be best to look at applying for planning permission.

Failing to schedule effectively

A huge factor in the planning phase is the time of year. If at all possible, avoid planning work in the winter as obstacles such as frozen ground and bad weather can cause huge delays, meaning the extension work could leave the rest of the house more vulnerable to the cold. Beginning work in springtime is ideal, especially with bigger projects.

Discuss estimated time frames with your contractors and plan accordingly. Be realistic with your scheduling; you mustn’t be forced to rush or cut corners.

If you are taking responsibility for arranging the delivery of materials, be more than generous with the time you allow for things to arrive to ensure that delivery delays don’t lead to bigger hold-ups in the wider project.

Not thinking of the bigger picture

This is a mistake that can be made at any point throughout the process of building an extension.

In the initial planning phase, it is important to keep in mind how the extension will impact the rest of the house, both now and in the future. It is vital to assess how an extension may impact the flow between rooms, as well as consider how this may affect the functionality of existing rooms. Consider how the needs of the household may change over the months and years, ensuring your extension is planned with this in mind.

Throughout the building process, don’t allow the questions and issues that are likely to pop up to distract you from your end goal. Keep your vision in mind with each decision you are required to make, and allow this to keep you motivated and on track.


Content by Bradley Mackenzie, RICS accredited valuer at chartered surveyors Stokemont

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