Conservatory vs Extension Costs UK 2024

Understanding the Cost Difference Between Conservatories and Extensions

When you're considering adding living space to your home, choosing between a conservatory and a traditional extension will have a major impact on your budget. Both options carry distinct financial implications that go well beyond basic construction costs. A conservatory typically costs between £3,000 and £25,000 depending on size and materials, whilst a brick extension generally ranges from £15,000 to £60,000 or more. The price difference comes down to building regulations, structural requirements, and long-term maintenance needs.

The financial decision involves more than just the initial cost. You'll also need to factor in planning permission fees, Building Regulation approvals, and ongoing heating expenses. Many homeowners assume extensions are always more expensive, but high-end conservatory designs can command premium pricing too. Understanding what drives these costs helps you make a decision tailored to your property and needs.

Conservatory Construction Costs Explained

Conservatories offer a lower entry point for adding usable space, with most projects falling into the £8,000 to £20,000 bracket for standard residential properties. A single-storey conservatory measuring approximately 4 metres by 3 metres typically costs £6,000 to £15,000 including materials and labour. Larger structures or those using premium materials like hardwood frames can exceed £25,000. Construction is straightforward—essentially a framework with glazing—which makes it cheaper and faster than traditional building methods.

Material choice has the biggest impact on your final bill. Aluminium frames are the most affordable option at £4,000 to £12,000 for standard sizes, offering durability with minimal maintenance. uPVC conservatories range from £5,000 to £15,000, combining affordability with reasonable insulation properties. Hardwood or timber designs cost £10,000 to £25,000, delivering superior aesthetics and thermal performance. Polycarbonate roofing costs less than glass alternatives, though glass lets in more light and lasts longer.

You'll also need to budget for foundations (typically £1,000 to £3,000), electrical installation (£500 to £2,000), and heating systems (£1,500 to £5,000). Most conservatories under certain square meterage thresholds avoid Building Regulation approval, which significantly reduces costs associated with inspections and compliance documentation.

Traditional Extension Costs and Considerations

Brick or timber-frame extensions represent substantial investments, with costs typically starting at £15,000 for smaller projects and reaching £100,000 or more for larger additions. A modest single-storey brick extension of 4 by 3 metres generally costs £18,000 to £35,000, reflecting more complex construction requirements. The price covers proper foundations, brickwork, roofing, plastering, decoration, and full Building Regulation compliance.

Labour is usually your biggest expense, often accounting for 40-50% of total costs. Skilled bricklayers, plasterers, electricians, and plumbers charge premium rates, particularly in London and south-east England. Materials—bricks, mortar, roof tiles, and timber—average £8,000 to £18,000 for similar-sized projects. Regional variations are significant; extensions in Yorkshire might cost 20-30% less than identical structures in Surrey or Greater London.

Extensions invariably require Building Regulation approval and planning permission unless they fall within Permitted Development Rights for certain configurations. This adds £500 to £2,000 in application fees, plus professional fees for architects or structural engineers ranging from £1,500 to £5,000. Inspections during construction add further expenses and extend project timelines.

Planning Permission and Regulatory Costs

Regulatory requirements create a fundamental cost difference between these options. Most conservatories bypass planning permission entirely under Permitted Development Rights if they measure under 30 square metres and don't exceed the original house's footprint. This exemption saves approximately £500 to £1,000 in local authority application fees plus professional consultation costs.

Extensions face stricter scrutiny depending on location, size, and proximity to boundaries. The following scenarios typically require formal approval:

Structures exceeding certain depth or height thresholds relative to the original building
Properties within conservation areas or on listed buildings
Extensions positioned closer than regulated distances from neighbouring properties
Projects in designated areas including National Parks or Areas of Outstanding Natural Beauty
Any addition where the extension would increase the original house's footprint by more than specified percentages

Building Regulation approval costs approximately £200 to £600 for application fees, plus inspection charges of £150 to £400 per visit. Structural engineers charge £500 to £2,000 for calculations and drawings, sometimes less if your architect handles the design. These regulatory expenses rarely apply to conservatories, which gives them a significant financial advantage during the planning phase.

Long-Term Running Costs and Maintenance

The true financial picture emerges over a conservatory's lifespan when you account for heating and cooling expenses. Inadequately insulated conservatories lose heat rapidly and need supplementary heating systems that substantially inflate monthly utility bills. A poorly-designed conservatory might cost £30 to £60 monthly to heat during winter, whereas a traditional extension with superior insulation maintains the same comfort for £10 to £25. Over ten years, this difference exceeds £2,400, offsetting your initial savings.

Modern conservatories with high-performance glazing, thermal roofing, and integrated heating systems reduce this penalty considerably. Investing an additional £3,000 to £8,000 in enhanced insulation measures pays off through reduced operational costs. Traditional extensions incorporating cavity walls and modern insulation standards deliver superior energy efficiency from day one without requiring upgrades.

Maintenance is another cost often overlooked. Conservatory glazing needs regular cleaning to maintain appearance and light transmission; neglected frames accumulate algae and discolouration. Seals and gaskets typically require replacement every ten to fifteen years, costing £500 to £1,500. Extensions built to modern standards need minimal maintenance beyond standard household upkeep, spreading costs more evenly across longer periods.

Comparing Total Cost of Ownership

Initial capital expenditure is only part of the picture when evaluating conservatory versus extension investment. A £12,000 conservatory appearing cheaper than a £25,000 extension becomes significantly less attractive once you add heating, maintenance, and replacement costs over twenty years.

Consider this practical comparison for a 4x3 metre addition:

Conservatory: £12,000 initial cost + £40 monthly heating (average) over 10 years = £16,800 total + £1,500 maintenance = £18,300
Extension: £28,000 initial cost + £15 monthly heating (average) over 10 years = £29,800 + £500 maintenance = £30,300

The extension costs approximately £12,000 more over a decade, yet provides superior functionality, increased property value, and significantly better year-round usability. For tight budgets, conservatories offer immediate space solutions. For long-term investments prioritising comfort and returns, extensions typically deliver superior financial outcomes despite higher upfront costs.

Making Your Choice: Practical Next Steps

Your decision should balance your immediate budget constraints against your long-term usage plans. Conservatories work well for homeowners wanting quick, affordable additions for seasonal use or specific purposes without substantial planning complications. Extensions suit those building permanent living space with superior comfort, insulation, and property value implications.

Start by obtaining detailed quotations from established providers familiar with your area's regulatory environment. Compare quotes from 3 providers specialising in your chosen option to understand realistic local pricing. Request breakdowns identifying labour, materials, and contingency allowances separately. Ask about hidden costs including utility connections, groundwork complications, and potential upgrades during construction.

Check with your local planning authority regarding Permitted Development Rights applicable to your property; conservation area status or listed building designation substantially changes what you'll need to do. Budget 10-15% additional contingency for both project types, allowing for unexpected structural discoveries or price fluctuations during construction.