July 30, 2025
Home extensions are one of the most popular ways to add space and value to a property. Whether it's creating an open-plan kitchen, adding an extra bedroom, or building a garden room, extensions can significantly improve a home’s function and appeal. But despite the initial excitement and investment, many homeowners find themselves with regrets once the dust has settled. These aren’t just minor inconveniences—they can range from budget overruns to layout issues that affect daily living.
Understanding the most common regrets people have after completing a home extension can help you avoid the same pitfalls. In this article, we’ll explore the biggest post-extension disappointments, discuss why they happen, and offer practical advice to help you make informed decisions for your own project.
One of the most common regrets is not budgeting enough. Homeowners often focus on the quoted build cost and fail to account for the additional expenses that quickly add up—such as planning fees, surveys, design revisions, temporary accommodation, unexpected structural work, landscaping, and final finishes like flooring or lighting.
Why it happens: Optimism bias and underestimating the scope of the project.
How to avoid it: Build in a contingency of at least 15–20%. Get detailed quotes, include everything from structural changes to final decorating, and be honest about what you can afford from the outset.
A surprising number of homeowners focus too much on the immediate visual impact and not enough on how the new space will function in the long term. For example, an extension might add square footage but disrupt the natural flow of the home or isolate certain rooms.
Why it happens: Excitement during planning often overshadows practical living considerations.
How to avoid it: Consider how you use your home on a daily basis. Work with a designer or architect who thinks holistically about space, flow, light, and transitions between rooms.
Many homeowners complete their extension only to realise that parts of the new or existing space are now dark and gloomy. Extending often means building further into the garden or out to the side, potentially blocking light to the original rooms.
Why it happens: Lack of planning around the impact of the build on light direction and flow.
How to avoid it: Use tools like 3D modelling or solar studies. Incorporate skylights, larger windows, or internal glazing to allow natural light to penetrate deeper into the home.
Adding square footage often means reducing the size of the garden or outdoor area. Homeowners later regret losing valuable outdoor living space—especially in families with children or pets, or those who enjoy gardening or entertaining.
Why it happens: Focus is often on gaining internal space without considering what’s being lost externally.
How to avoid it: Strike a balance. Create a layout that works inside and out, and consider multi-functional outdoor areas like patios, terraces, or garden rooms.
Some homeowners push forward with designs they love, only to face planning rejection or major delays. Others discover too late that their permitted development rights don’t apply or that local restrictions require design changes.
Why it happens: Assuming planning is a formality, or relying solely on builder advice.
How to avoid it: Consult with a planning expert or architect before making major decisions. Check local council guidelines and understand what permissions your specific property needs.
Poor workmanship, project delays, miscommunication, and disputes over costs are all too common. Some homeowners go with the cheapest quote, only to find themselves paying more to correct mistakes later.
Why it happens: Rushing the decision or focusing solely on price.
How to avoid it: Do your due diligence. Check credentials, read reviews, visit past projects, and speak directly to previous clients. Always use a written contract and agree on clear milestones and payment terms.
Many homeowners fail to factor in energy efficiency when building an extension, resulting in higher utility bills, cold spots, or overheating. Modern extensions should ideally be more efficient than the original structure.
Why it happens: Efficiency considerations are often treated as optional extras.
How to avoid it: Use high-quality insulation, triple-glazed windows, airtight construction methods, and energy-efficient systems from the beginning. Incorporate passive design principles where possible.
Trying to save money by skipping an architect or interior designer often leads to disappointing results. Poor layout, mismatched finishes, or awkward transitions between old and new parts of the house are common issues.
Why it happens: DIY culture and cost-saving mindsets.
How to avoid it: Involve professionals early. Even if you don’t use a full design service, a consultation can help set your project on the right path and avoid costly reworks later.
An extension might suit your needs today but could become a problem in the future. For example, failing to futureproof for growing families, mobility issues, or changing lifestyles can lead to expensive modifications down the line.
Why it happens: Planning is often focused solely on current needs.
How to avoid it: Think five or ten years ahead. Consider flexible layouts, ground-floor bedrooms or bathrooms, and universal design features that can adapt over time.
Homeowners can overextend, adding more square footage than is typical for the area, resulting in poor return on investment and difficulties selling the home later.
Why it happens: Personal ambition overtakes market research.
How to avoid it: Research comparable properties in your area and speak to local estate agents. Ensure your investment aligns with the market and adds true resale value.
You should allocate at least 15–20% of your total budget for unexpected expenses. Issues like structural complications, price fluctuations, or changes to the design often arise mid-project.
Not always. Some extensions fall under permitted development rights, but this depends on your property's location, type, and the size of the extension. Always confirm with your local planning authority before starting.
It depends on the scale of the project. For smaller or rear extensions, it’s often manageable with some disruption. For larger projects, especially those involving major structural work or the kitchen, temporary accommodation may be necessary.
If well-designed and suited to the property and location, extensions can add significant value. However, overbuilding or poor-quality work can do the opposite. Speak with local estate agents to understand what buyers in your area value most.
Ask for recommendations, check online reviews, visit previous projects, and verify credentials. Use trade associations like the Federation of Master Builders or TrustMark as starting points. Always use a written contract and agree clear terms.
Incorporate large glazing features such as bifold doors, skylights, or roof lanterns. Consider orientation—south-facing extensions generally get more sunlight—and use reflective surfaces and light colours to enhance brightness.
A home extension should be an exciting opportunity to enhance your living space, improve your lifestyle, and add value to your property. But as many homeowners discover, without the right preparation and guidance, it can come with a number of regrets. From budget missteps to design oversights, the consequences of rushed decisions or short-sighted planning can linger long after the project ends.
By learning from others' experiences and working with trusted professionals, you can avoid these common pitfalls. Plan realistically, think holistically about your home, and always consider how the extension will serve you in both the short and long term. With careful attention to detail and clear priorities, your extension can be a positive and lasting investment.
If you’re planning a renovation, extension, or full home transformation, visit our website Milkov & Son Construction to explore our expert services and recent projects. Take the first step toward creating your dream space by contacting us online or calling +44 7951 625853.
