Frequently Asked Questions
A clear, practical video guide to the renovation questions we’re asked most often by UK homeowners and property owners.
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The cost of an extension depends on its size, complexity, location, and the level of finish, which is why there’s no single price that applies to every project. Early ballpark figures can be useful, but the only reliable way to understand cost is once the extension is properly designed and costed. That’s when informed decisions can be made to control the budget through value engineering.
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Builders don’t guess prices - accurate quotes are built from detailed drawings that show materials, structure, and how long each trade will take. The more information a builder has, the more precise the cost, which is why early “ballpark” figures often change once full plans are issued. A proper quote takes time to prepare, but it’s far more reliable than a quick estimate.
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Architect’s or Chartered Architectural Technologist’s fees can vary, but when you include all design-related costs - such as planning applications, structural engineering, and Building Regulations - most clients we work with spend around 5–10% of the total construction cost to get a project ready to build. This can be higher for more complex or rural projects, or homes with special constraints. Always check what’s included, as some designers only produce drawings, while others guide you through the entire design and approval process.
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Not always - some extensions can be built under permitted development rights, which allow certain works without planning permission. However, not all properties have these rights, particularly homes in conservation areas or on newer estates where they may have been removed, and restrictive covenants can also apply. The safest way to be sure is to check your conveyancing documents or seek professional advice before progressing your plans.
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In England and Wales, some extensions can be built without planning permission under permitted development rights, but strict limits apply. The rules vary depending on whether the extension is to the front, side, or rear of the house, and differ slightly between England and Wales. Materials, height, depth, and the original size of the house all matter. So it’s important to check the details before relying on permitted development.
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After you submit a planning application, it’s first checked for completeness during validation before it’s officially registered. It then goes through a public consultation period, followed by a detailed assessment against local planning policies, where changes or extra reports may be requested. The process isn’t quick, but understanding each stage helps set realistic expectations and improves your chances of approval.
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You end up loving the design by choosing a professional with a clear, collaborative process - not just a particular style. A good architect or Chartered Architectural Technologist takes time to understand how you live, what you value, and what will genuinely improve your daily life, then translates those insights into meaningful design decisions. That process is what turns vague ideas into a home that feels personal, not generic.
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A Live Home Design Meeting is a full-day collaborative session where you work directly with your designer while your home is drawn and tested in real time. Instead of waiting weeks for revisions, different options are explored live using 2D and 3D CAD so you can compare ideas, ask questions, and make confident decisions on the spot. The result is a more personal design, fewer revisions, and a faster, more cost-effective process.
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An extension or renovation doesn’t automatically add value - and it’s normal for a property to be worth less than you’ve spent on it in the short term. Value is influenced by local price ceilings, build costs, and how well the design aligns with what buyers in your area actually want. With good research and a well-considered design, you can significantly improve your chances of adding long-term value while also improving how you live in the home.
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In many cases, you can stay in your home during building works, especially for extensions where the new space is constructed before breaking through to the existing house. However, construction is noisy, dusty, and disruptive, and temporary loss of kitchens, bathrooms, or quiet working space can make daily life difficult. Whether you should stay depends on the scale of the works, your tolerance for disruption, and whether alternative accommodation is a more practical option.
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Architects and Chartered Architectural Technologists are both formally qualified and regulated professionals. But they follow different routes to qualification. Architects through a longer academic pathway, and Chartered Architectural Technologists typically follow a balance of education and assessed practical experience.
Non-Chartered Designers can also produce good work, but they are not regulated in the same way and are not required to meet professional standards, carry specific insurances, or follow a code of conduct.
In practice, experience and how someone works with clients often matter just as much as their job title.
Watch Explainer Video on Youtube -
You don’t always need a drain survey, but it’s strongly recommended for extensions because underground drains aren’t always where you think they are. Sewer records are only indicative, and building too close to a drain (especially a public sewer) can result in costly redesigns or even being forced to dig the work back up. A CCTV drain survey removes the guesswork and helps avoid expensive surprises later.
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In most cases, yes - if your project involves structural changes, a structural engineer is essential to ensure the work is safe and compliant. Their calculations are usually required for Building Regulations approval, and without them, parts of your build could be technically non-compliant or even illegal. Skipping this step often leads to delays, redesigns, and higher costs further down the line.
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You can save money by managing parts of a build yourself, but for first-time projects it often leads to delays, mistakes, and higher overall costs. Construction relies heavily on experience, sequencing, and knowing how different trades work together - small errors in preparation, coordination, or ordering materials can quickly become expensive. In many cases, paying for professional management costs less than learning through trial and error.
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Building Regulations are the legal standards that ensure homes in the UK are safe, energy-efficient, and properly constructed. They’re enforced by Building Control using detailed Approved Documents, which is why clear Building Regulations drawings are so important for compliant construction. Skipping or misunderstanding them can lead to costly remedial work - or even make a home unsafe or difficult to sell.
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Choosing a good builder is about more than price - it’s about experience, stability, and professionalism. Look for builders who are properly insured, experienced in similar projects, happy to work under a written contract, and paid through staged payments linked to progress. Taking time to check references and compare multiple quotes can help you avoid costly mistakes later.
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The build time for an extension varies depending on the size of the project, the builder’s setup, and how trades are coordinated. Most domestic extensions take around three to six months on site, with larger or more detailed projects taking longer. Delays are common, so planning for flexibility helps reduce stress during the build.
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It isn’t mandatory but it’s highly recommended - even for smaller domestic projects. Without one, delays, changes, and disagreements are much harder to resolve because there’s nothing clear to refer back to. A simple contract can protect both you and your builder without adding unnecessary complexity.
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A good building contract is built around four principles: how changes are handled, what the builder is responsible for and how long it should take, how communication works, and how payments are made. These basics remove ambiguity and prevent most disputes before they arise. A strong contract also sets out what happens if things go wrong, so issues can be resolved calmly rather than turning into conflict.