Building an extension is an effective way to add space and value to your home, but it’s important to approach the project with realistic expectations. While most homeowners budget for the main construction work, many are caught off guard by additional expenses that arise along the way. These hidden costs can significantly impact your overall budget if not planned for in advance. But what are the hidden costs of building an extension? And how can working with a professional team like us here at DB Joinery, help you avoid these hidden costs?
So what are the hidden costs of building an extension and how can these be avoided?
There are a number of common causes for additional, unforeseen costs associated with home extensions, including:
- Planning and design fees- One of the first surprises for many homeowners is the cost of planning and design. Architectural drawings, structural engineer reports, and planning applications often come with separate fees. While these are essential for ensuring your extension meets building regulations and planning requirements, they can add up quickly. Before the work starts, you should ask for a full breakdown of all design and planning costs. Some building companies, like us here at DB Joinery, offer full project management, from the design to the build itself, which can help keep costs transparent and manageable.
- Site preparation and groundworks- Groundworks are often overlooked during initial budgeting, but they can be one of the most expensive aspects of a project. Issues such as poor soil quality, uneven ground, or the need to relocate drainage systems can dramatically increase costs. These factors are often only discovered once work begins. This can be avoided with a thorough site survey carried before starting. A professional survey can identify potential problems early, allowing you to budget for them upfront.
- Utilities and Services- If your extension requires new plumbing, electrical wiring, or heating systems, these costs can escalate quickly. In some cases, the existing boiler may not have enough capacity to heat the new space, meaning an upgrade is necessary. Similarly, moving meters or adding new electrical circuits can add hundreds, if not thousands, to your bill. An experienced builder, like us here at DB Joinery, will be able to assess whether your current systems will cope and provide an accurate estimate for any necessary upgrades.
- Unexpected structural issues- Older properties in particular can present surprises once walls are opened up. Damp problems, asbestos, or inadequate foundations may require urgent attention before the extension can proceed. These issues can cause delays and significantly increase your overall spend.
- Finishing touches and upgrades- Many homeowners budget for the build but forget about the finishing touches, such as the flooring, lighting, decorating, and landscaping. Even small upgrades such as premium tiles, bi-fold doors, or bespoke fittings can quickly increase costs if they weren’t accounted for initially. To avoid this, make a detailed list of all finishes you want and allocate a realistic budget for them. Always include a contingency of at least 10–15% of the total project cost for unexpected extras.
Why working with a professional team matters
One of the best ways to keep hidden costs under control is to work with an experienced and trustworthy team. A reputable builder will provide a clear, detailed quote that includes as many foreseeable costs as possible, reducing the likelihood of unexpected expenses. They will also handle planning, building regulations, and project management, ensuring your extension stays on time and within budget.
Here at D B Joinery and Building Services we offer a range of high quality services for all manner of joinery and building projects, across Preston and with wider Lancashire region. Why not get in touch today to find out more?