Loft Conversion Planning Permission & Building Regulations

What is the difference and what does it mean for your loft conversion?

It is generally realised that a form of permission is required for building work or alterations of properties. However, it may not always be clear how the planning and building regulations approval regimes differ.

Building regulations set standards for the design and construction of buildings to ensure the safety and health for people in or about those buildings. They also include requirements to ensure that fuel and power is conserved and facilities are provided for people, including those with disabilities, to access and move around inside buildings.

Planning permission seeks to guide the way our towns, cities and countryside develop. This includes the use of land & buildings, the appearance of buildings, landscaping considerations, highway access and the impact that the development will have on the general environment.

For many types of building work, separate permission under both regimes (separate processes) will be required. For other building work, such as internal alterations, buildings regulations approval will probably be needed, but planning permission may not be.

building regulations
planning permission

What Planning Permission Do I Need For A Loft Conversion?

  • Every Loft Conversions Is Different, And Each Local Authority Varies, But Here’s The Basics
  • Most Loft Conversions No Longer Need Planning Permission

The Legal History Of Planning Permission For Lofts:

In 2015 General Permitted Development (GPDO) came into force revoked The Town and Country Planning (General Permitted Development), which was the previous version of the legislation. Within this legislation was the “permitted development right”, which lofts are covered under. These development rights allow you to modify your building within a specific set of perimeters without the ned for planning permission.

What does this mean for your new loft conversions?

A loft conversion for your house is considered to be permitted development, not requiring an application for planning permission, subject to the following limits and conditions:

  • You can expand your existing roof volume by up to 50 cubic metres (terraced houses are only 40)
  • The extension can not go beyond the plane of the existing roof slope of the principal elevation that fronts the highway
  • No extension to be higher than the highest part of the roof
  • Materials to be similar in appearance to the existing house
  • No verandas, balconies or raised platforms
  • Side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor
  • Roof extensions not to be permitted development in designated areas
  • Roof extensions, apart from hip to gable ones, to be set back, as far as practicable, at least 20cm from the original eaves
  • The roof enlargement cannot overhang the outer face of the wall of the original house.

So what does that really mean, in english?

You don’t need planning permissions for nearly all dormers or mansard conversions completed to the rear of the building, so long as they do not exceed 50 cubic meters, which few do.

All roof rifts, all front or side facing dormers and some hip to gable loft conversions will need planning permission.

What are the exceptions?

It’s almost impossible to list all of the exceptions to the above, as each local authority is different, and many have conservation areas that have stricter rules applied. Our advice is, call us and we can guide you for your specific loft conversions in your area.

Put Us To The Test – Can We Convert Your Loft?

Building Regulations For A Loft Conversion In The UK


You now know what planning you might need, but what about building regulations?


As you have already read, building regulations have to be applied to all alterations to a building, but which one applies to a loft? That’s easy, they all do; from the base construction, to the electrical work, through to the insulation level and fire safety, they all apply to a loft conversion.

It would be silly or me to list all of the core regulation here, so here is a quick summary of the big one, not always the most obvious:

1) Construction – Any change to the building, must comply with very strict regulations as to what can be done and how. The construction of a dormer loft conversion, must be made to a minimum standard, such as the rafters being double bolted and so on. All of this means that the property is sturdy and able to take the weight and strains it could be out under from you and the great British weather..

2) Fire Doors – I don’t have to explain why this is here, but it does ensure that you are able to escape the building, safely and with minimal risk to you and your family. Different rules apply to different types of buildings, such as bungalows and houses. The main difference is escaping from a window above first floor level is not deemed suitable, so internal fire doors are needed.

3) Floor & beams – It is unlikely that the existing ceiling joists will be adequate to supported the weight loft conversions. To overcome this new floor joists are needed, and these must be support correctly either via supporting walls or steel beams.

4) Sound Insulation – This is required between habitable rooms.  With a terraced or semi-detached house, the building control body may also ask for sound insulation between the converted loft and the neighbours loft to be improved.

The list goes on and on, but you get the idea. TVM Loft Conversions have years of experience dealing with the regulations, and work closely with the local authority and supporting bodies to ensure our loft conversions are 100% within the regulations. On  almost every occasion, the roof space when we have finished is more structurally capable then when we start…

building rules and regulations

Book Your Free Design Consultation Today

We offer a free no obligation survey at your home to view, measure-up and discuss your specific needs.
Request A Call