Garage Conversion: Rules, Costs and Planning Permission

A complete guide to converting your garage into living space, covering planning rules, building regulations, costs and design considerations.

Converting a garage into living space is one of the most affordable ways to add a room to your home. It is typically cheaper than an extension because the basic structure already exists.

Do You Need Planning Permission?

In most cases, converting an integral garage (attached to and part of the house) does not require planning permission. It is treated as an internal alteration, which is permitted development.

However, you may need planning permission if:

• You live in a conservation area and the conversion changes the front elevation
• Your property has a planning condition requiring the garage to be kept for parking
• You want to significantly change the external appearance (e.g. the front elevation)
• You live in a listed building
• You are converting a detached garage into a separate dwelling (this always needs permission)

Check your original planning permission documents for any conditions relating to the garage. Also check whether your council has minimum parking standards for your area.

Building Regulations

All garage conversions require building regulations approval. Key requirements include:

• Damp proofing - garage floors are typically below the damp-proof course and will need a new DPM (damp-proof membrane)
• Floor insulation - the floor must be raised and insulated to meet thermal standards
• Wall insulation - existing garage walls may need insulation adding
• Structural opening - replacing the garage door with a wall, window and possibly a door requires proper structural support
• Ventilation - adequate ventilation for the new room
• Electrics - new circuits installed by a Part P qualified electrician
• Fire safety - fire separation between the new room and any attached garage or boiler

Typical Costs

• Basic conversion (single garage to bedroom/office): £8,000-£15,000
• Mid-range conversion (with en-suite or utility room): £15,000-£25,000
• High-spec conversion (bi-fold doors, underfloor heating, premium finishes): £20,000-£35,000
• Double garage conversion: £15,000-£40,000

Professional fees (architect/designer, structural engineer, building control) will add approximately £1,500-£3,000.

What Can You Convert a Garage Into?

• Extra bedroom - the most popular option, especially with an en-suite
• Home office - increasingly popular since the shift to hybrid working
• Playroom or family room
• Utility room and boot room
• Home gym
• Annexe for elderly relatives (may need planning permission if self-contained)

Design Considerations

• The garage door - most conversions replace this with a window and insulated wall. Consider keeping the garage door lintel as a feature or installing a large window to maximise light
• Ceiling height - garages often have lower ceilings than the rest of the house. Raising the floor for insulation reduces this further. Check you will have adequate headroom (minimum 2.1m, ideally 2.4m)
• Matching materials - use bricks, render, or cladding that matches the existing house for a seamless appearance
• Parking - losing a garage means losing covered parking. Consider whether you have adequate off-street parking remaining

Does a Garage Conversion Add Value?

A garage conversion typically adds 10-15% to your property's value - often significantly more than the cost of the work. However, in areas where off-street parking is scarce, losing the garage could reduce appeal to some buyers.