Bungalow Extensions: UK Costs, Design Ideas, and Planning Rules for 2026

Bungalows are some of the most sought-after properties in the UK — prized for their single-level living, accessibility, and generous plots. But they're also some of the most under-utilised in terms of space. If your bungalow feels cramped, extending or converting it can transform the property while preserving the qualities that make bungalows so desirable.

Extension Options for Bungalows

1. Rear Extension

The most common bungalow extension — extending the back of the property to create a larger kitchen-diner or living space.

• Cost: £30,000–£50,000 (20m²)
• Planning: Usually permitted development (up to 4m depth for detached, 3m for semi)
• Build time: 10–14 weeks
• Best for: Open-plan kitchen-diner with garden views

Bungalow rear extensions benefit from the same generous PD limits as houses. The Larger Home Extension scheme allows up to 8m for detached bungalows with prior approval.

2. Side Extension

Extending into the side garden to add a bedroom, bathroom, or utility room. Bungalows often have generous side plots.

• Cost: £25,000–£45,000 (15–20m²)
• Planning: Usually PD if single-storey and no wider than half the original house
• Build time: 10–14 weeks
• Best for: Additional bedroom with en-suite, utility room, or home office

3. Wrap-Around Extension

Combining rear and side extensions in an L-shape for maximum ground-floor space. See our wrap-around guide for the general approach.

• Cost: £45,000–£80,000 (25–35m²)
• Planning: Usually PD if within the standard limits
• Build time: 12–16 weeks
• Best for: Transforming a 2-bed bungalow into a spacious 3-bed with open-plan living

4. Chalet Bungalow Conversion (Adding a First Floor)

The most dramatic option — adding bedrooms and bathrooms upstairs while keeping living spaces on the ground floor. This effectively doubles the usable area.

• Cost: £50,000–£100,000+
• Planning: Always requires planning permission (changes the roofline and massing)
• Build time: 16–24 weeks
• Best for: Maximising space on a tight plot, creating a family home from a small bungalow

5. Loft/Roof Conversion

If the existing roof has sufficient height (2.2m+ at the ridge), converting the loft space adds rooms without extending the footprint.

• Cost: £30,000–£60,000
• Planning: Dormers and raised ridges always need planning permission on bungalows
• Build time: 8–12 weeks
• Best for: Adding bedrooms without losing garden space

See our loft conversion types guide for detailed options.

Cost Breakdown: Bungalow Rear Extension (20m²)

| Item | Cost | |---|---| | Foundations and groundworks | £4,000–£7,000 | | External walls | £5,000–£8,000 | | Roof (flat or pitched) | £3,000–£6,000 | | Windows and doors (bifolds or sliding) | £3,000–£6,000 | | Internal walls and plastering | £2,000–£3,500 | | Electrics | £1,500–£2,500 | | Plumbing (if kitchen relocation) | £1,000–£2,500 | | Floor finish + underfloor heating | £1,500–£3,000 | | Building Regulations | £500–£1,000 | | Professional fees (architect + engineer) | £2,500–£5,000 | | Contingency (10%) | £2,500–£4,500 | | Total | £27,000–£49,000 |

Add 25–40% for London and the South East. Use our free quote calculator for a location-specific estimate.

Chalet Bungalow Conversion: What's Involved

Converting a single-storey bungalow into a chalet (1.5 or 2-storey) is a major project:

Structural Work

• Remove existing roof structure (or lift it temporarily)
• Build new first-floor walls (dwarf walls or full-height)
• Install new floor joists between ground and first floor
• New roof structure with dormers or full gable ends
• Staircase from ground to first floor

Services

• Extend plumbing to first-floor bathrooms
• Extend electrical circuits and consumer unit
• Heating — extend radiator system or add new circuits
• New fire safety measures (mains-wired smoke alarms, escape windows, fire doors)

Cost Breakdown

| Item | Cost | |---|---| | Temporary roof and structural strip | £3,000–£6,000 | | New first-floor structure | £8,000–£15,000 | | New roof with dormers | £10,000–£20,000 | | Staircase | £2,000–£5,000 | | First-floor rooms (2 bedrooms + bathroom) | £8,000–£15,000 | | Plumbing and heating extension | £3,000–£6,000 | | Electrics | £2,000–£4,000 | | Scaffolding | £1,500–£3,000 | | Professional fees | £4,000–£8,000 | | Contingency (10%) | £5,000–£10,000 | | Total | £46,500–£92,000 |

Planning Considerations for Bungalows

Height Is the Key Issue

Bungalows have lower ridge heights than houses, so the permitted development rule that extensions "must not exceed the height of the existing house" is more constraining. A flat-roofed rear extension at 3m height is usually fine, but a pitched roof may push the limits.

Neighbours

Bungalow owners tend to be older and particularly sensitive to overlooking. A chalet conversion that adds first-floor windows looking into a neighbour's garden will generate objections. Consider:

• Obscure-glazed side windows (required under PD for upper floors)
• Roof windows rather than dormers on sensitive sides
• Setting back the first floor from boundaries

Party Wall Act

Semi-detached bungalows need Party Wall notices for extensions near the shared wall. Start this 2–3 months before construction.

Conservation Areas

Many bungalow estates built in the 1920s–1960s are now in conservation areas. Check with your council before assuming PD rights apply.

Design Tips for Bungalow Extensions

Preserve Single-Level Living

The greatest asset of a bungalow is accessibility. If extending for a family member with mobility needs, keep the main living spaces, at least one bedroom, and a bathroom on the ground floor. This is increasingly important for future-proofing and adds value.

Maximise Natural Light

Bungalows can feel dark due to their low ceilings and deep floor plans. Use:

• Roof lanterns over the central area (£2,000–£5,000)
• Full-width glazing to the rear (bifolds or sliding doors)
• Clerestory windows (high-level glazing) along internal walls
• Light tubes in corridors (£300–£600 each)

Open-Plan Layout

Bungalow rooms are often small and compartmentalised. Knocking through walls during an extension creates the flowing layout that modern buyers expect. A structural engineer (£300–£600 for beam calculations) makes this safe and compliant.

Match the Character

Bungalows have a distinctive low-profile character. Extensions that respect this — using matching materials, similar roof pitch, and proportionate window sizes — look better and are more likely to gain planning approval.

Next Steps

1. Decide your goal — more ground-floor space, or add a first floor?
2. Check PD rights — measure your ridge and eaves heights carefully
3. Appoint an architect — bungalow design needs careful proportioning
4. Get a structural engineer for any wall removal or upward conversion
5. Start Party Wall notices if semi-detached
6. Get a cost estimate — use our free calculator or browse extension costs by city
7. Budget for hidden costs — professional fees, Building Control, and making good