House extensions

A: Planning permission relates to how your extension looks and its impact on the surrounding area, while building regulations ensure that your extension is structurally sound, energy-efficient, and safe. Even if your extension falls under permitted development, it must still comply with building regulations.

A: In England, planning permission for a house extension currently costs £206. This fee applies to alterations/extensions to existing dwellings for a single household. The cost may vary slightly depending on your local authority, and there may be additional fees for other services such as pre-application advice.

A:  If your application is refused, you have several options. You can modify your plans based on the feedback received and resubmit (which is free within 12 months of refusal), appeal the decision, or explore alternative solutions that might fall under permitted development rights. We recommend discussing with your architectural specialist to determine the best approach for your specific situation.

A: A Lawful Development Certificate (LDC) proves your extension was legal at the point of construction. While not mandatory, we recommend obtaining one if your project falls under permitted development rights, as it provides documentation that your extension complies with regulations—particularly valuable if you sell your property in the future. An LDC application costs approximately £103 in England.

A: Extension costs vary widely depending on size, complexity, location, and materials. As a rough guide, you might expect to pay:

• Single-storey extension: £1,200-£2,000 per square metre
• Double-storey extension: £1,500-£2,500 per square metre
• Kitchen extension: £1,800-£3,500 per square metre (excluding appliances)

These figures can be higher in London and the South East. Every project is unique, and we recommend getting detailed quotes from contractors for your specific requirements.

A: When planning your extension budget, remember to factor in:

• Architectural services and design fees (typically 5-10% of construction costs)
• Planning permission and building regulation fees
• Structural engineer costs if required
• Party wall agreements, if applicable
• Potential temporary accommodation during major works
• Contingency fund (we recommend setting aside 10-15% of your budget)

A: Balancing the budget can be tricky, especially when you’re trying to achieve your dream space. To manage costs effectively:

• Be clear about your priorities from the start
• Consider a phased approach if the budget is tight
• Choose standard-sized materials where possible
• Maintain open communication with your architectural service provider and builder
• Avoid making changes once construction has begun
• Research potential suppliers and compare quotes

A: The timeline for a house extension typically includes:

• Initial consultation and design phase: 1-2 months
• Planning permission (if required): 8-12 weeks for decision
• Building regulations approval: 4-8 weeks
• Construction: 3-6 months for a simple extension, longer for complex projects
• Interior fitting and finishing: 1-2 months

In total, you should allow anywhere from 6 to 12 months for a straightforward extension, potentially longer for more complex projects.

A: While it’s usually possible to remain in your home during construction, you should be prepared for some disruption. Discuss your specific circumstances with your builder, as factors like demolition work, utility disconnections, and the scale of the project will affect your living conditions. For extensive works, you might consider temporary accommodation during the most disruptive phases.

A: The main stages of construction include:

1. Site preparation and foundations
2. Wall construction
3. Roof structure and covering
4. Windows and external doors
5. First fix (structural elements, plumbing, electrics)
6. Plastering and floor screeding
7. Second fix (fixtures, fittings, decorating)
8. Final touches and snagging

A: For a cohesive design;

• Consider matching materials to your existing property
• Think about the roof pitch and window style
• Discuss complementary vs. contrasting approaches with your architectural service provider
• Review the neighbourhood character for contextual inspiration
• Use 3D visualisations to help imagine the finished result

A: A well-designed extension can significantly increase your property’s value, potentially by 10-30%, depending on location, quality, and the additional space created. However, the value of all assets can fluctuate, so no investment is ever guaranteed. Consider both your immediate living needs and potential long-term financial benefits.

A: Yes, you should notify your insurance provider both before work begins and after completion. Your premium will likely increase to reflect the higher rebuild cost, but failing to inform them could invalidate your policy. Also ensure your builder has appropriate insurance coverage during the construction phase.

A: Incorporating energy efficiency from the design stage can reduce running costs and environmental impact:

• Install high-performance insulation
• Choose energy-efficient windows and doors
• Consider renewable heating options like air source heat pumps
• Incorporate passive solar design principles
• Install smart controls for heating and lighting
• Consider solar panels or green roofs where appropriate