20+ Years Experience

Loft Conversions Nationwide

Loft Conversion Costs

Free No-Obligation Quote

Do You Need Planning Permission To Convert A Loft?

A loft conversion can add a lot to your home, but it can also be a big project that often seems quite disruptive. As such, many people do not actually know how these conversions fall under planning permission requirements or how they should be designing their new lofts.

It is important to remember that each loft conversion job can be completely different. You are often working around the existing roof structure and trying to minimize costs wherever possible, and this means that there is not a universal standard for how a loft “should” fit onto your home.

As a loft conversion specialist company with a huge pool of experience to draw from, we understand how to optimize loft designs for a range of different roles and spaces. This includes making sure that lofts fall within planning permission requirements and boundaries whenever possible.

What is planning permission?

Planning permission is effectively the process of asking for formal approval to carry out some building work. This is not always needed but is most often required for larger-scale changes, such as expanding your original house or adding large roof extensions.

The more significant the change is, and the more space it takes up, the more likely you are to need planning permission.

In the case of loft work, you may need loft conversion planning permission if you are adding a significant amount of loft space or making a major adjustment to the profile of your existing house.

Can you get a loft conversion without planning permission?

Planning permission is a binary thing – either you need it or you do not. A large part of this comes from how the loft conversion is designed and how that loft conversion will fit onto your property. In general, disruptive and larger-scale loft conversions tend to need planning permission far more often.

Can you rely on permitted development rights?

However, it is entirely possible to get a loft conversion through permitted development rights alone. This bypasses the need for planning permission but also requires you to follow certain restrictions or make changes to the way that the loft would impact your existing house and roof structure.

What is permitted development?

Permitted development rights are a set of criteria that allow you to construct things without needing planning permission. Many loft conversion types fall under permitted development rights due to their minor impact on anything but the existing roof slope.

When is a loft conversion permitted development?

Fitting within permitted development rights requires that the conversion adheres to certain limits and conditions. This can include things like a limit on the amount of roof space that can be taken up or whether the loft will exceed the height of the existing roof’s peak.

Most lofts are naturally going to fall under permitted development rights, but this is not always the case. Our experts can help you break down these individual points and investigate whether you would need planning permission on your behalf.

What if I already started the project?

If you have already began lot conversion without planning permission, you can usually seek retroactive planning permission. The government will usually allow this to go through as normal, although it can cause problems if your current project has major planning permission issues.

How much does planning permission cost?

If you need planning permission, then you have to submit an application for the loft conversion. This includes an application fee that has to be paid, the costs of which can vary quite heavily depending on where you live.

In England, Scotland and Northern Ireland, fees tend to be around £200, increasing with the scale and complexity of the loft conversion. In Wales, the starting price tends to be around £300.

Certain applications have no fee, but these are often in highly specific situations. In most cases, if you need planning permission, then you will generally have to pay at least £200 to submit your proposed plan for review.

How long does planning permission take, and how long does it last?

Your local planning authority has an obligation to reply to your loft conversion application as fast as possible, which often means that it will be checked within eight weeks at most. However, more complex proposals can require almost twice as long.

Planning permission itself is valid for up to three years. This time limit is only for the start of the work – it is entirely possible to begin the loft conversion project on the final day of planning permission and complete it after the approval has expired.

What impacts planning permission?

If loft conversions do not fall under permitted development, then they require planning permission. However, this permission itself can change quite heavily based on a range of factors, many of which influence how long it takes to receive approval.


Generally, complexity plays a large part in planning permission. The more complex your loft conversion is, the more details need to be checked. A simple roof light loft conversion only takes a short time to inspect, but balconies or raised platforms need far more scrutiny.

Simplified loft conversions are easier to inspect, making them more likely to get faster responses – if they even require planning permission in the first place. This also makes it less likely for them to violate important building regulations.


Larger loft conversions need more significant levels of building regulations approval. Adding a small amount of loft space is very different from turning your entire roof structure into a new room, especially if it leads to the roof slope being heavily modified.

This matters even more if your loft conversion is going to influence other people’s homes. Loft conversions that extend your current roof might block light or overshadow part of their garden, something that they sometimes have a right to complain about.


Design can sometimes be a factor in planning permission. Most loft conversions are meant to blend in with the house they are attached to, and using the same materials and style is often important to getting faster approval.

While this might not stop you from being approved, some local council planning departments issue design guides to assist with this. This is because a poorly designed loft conversion can actually reduce your home value and the value of homes around yours.

Building Regulations Approval

Following core building regulations is important for getting planning permission. Taking major fire safety risks or not including any accessible roof windows can be grounds for getting your proposal ignored, even if you are only modifying an existing space.

A loft extension still needs to follow building regulations to the letter. Our experts can help you understand the specific requirements of modern building regulations and how to seek approval for loft conversions that use unconventional designs or layouts.

Conservation Areas

A house in a conservation area requires specific planning permission, and permitted development rights often do not apply in the same way. This is because listed buildings and protected properties usually have to retain the same basic shape and design, limiting what you can do with them.

Preserving Outstanding Natural Beauty

These areas heavily limit what you can do with the exterior of the home, but adding internal changes like new floor joists is usually fine. Either way, you will need to seek planning permission, as well as approval from whichever organisation currently has control over the area.

For example, getting permission for a loft conversion depends on the restrictions in those conservation areas and world heritage sites. You may not be allowed to add side-facing windows or modify the roof pitch, but you might be able to modify previous roof extensions or add a new space-saving staircase.

What are the loft conversion building regulations?

Understanding the regulations behind creating a loft conversion can be extremely important. Even the most basic dormer lot conversion requires careful planning and a deep understanding of what you are allowed to do, especially if the loft conversion work is going to take a lot of time and effort to achieve.

Room Requirements

If you want to use a loft conversion space as a liveable room, then you need to follow certain basic requirements. This means having things like at least one window, a door that provides privacy (especially in the case of a bedroom) and enough headroom to keep the space usable.

This is something that our loft conversion experts can help with, although most conversion plans will already cover these basics anyway.

Stairway Regulations

Stairs have their own set of regulations that need to be followed with any loft conversion project. Staircases have no minimum width, but a width of 600-750mm is the most recommended option. You also cannot have more than 16 steps on a single flight without breaking the stairs up with a flat landing/platform.

The rise (height) of a step can be between 150mm and 220mm, while the going (length) falls between 223mm and 320mm. You also need at least 2,000mm of headroom throughout the entire staircase.

Fire Safety Regulations

A loft conversion needs certain fire protection steps and tools to ensure that inhabitants are kept safe during a potential fire. This includes fire doors to replace existing loft doors, at least one smoke alarm, fire-resistant walls to limit fire spread, and a viable escape route if the room begins to burn.

Direct fire prevention measures such as sprinklers are not necessary but can be a good addition to some loft conversions. However, this will require extra plumbing, which often has its own specific requirements.

Plumbing Regulations

Any loft conversion with its own plumbing and pipework needs to follow the usual rules for plumbing a room. This is something that conversion experts like us can help manage – we are able to call in the right specialists to get the work done quickly and non-disruptively.

Floor Joists Regulations

Converting a traditional loft into a usable roof space often requires the existing ceiling joists to be replaced since the originals are not always going to be suitable for acting as flooring. There are specific regulation sizes that you need to follow when getting new ones installed.

  • All new floor joists must have at least 100mm of insulation between them
  • 47 x 145mm joists must span up to 2.89m
  • 47 x 170mm joists must span up to 3.38m
  • 47 x 195mm floor joists at 400mm must span up to 3.87m
  • 72 x 145mm must be up to 3.33m
  • 72 x 170mm must be up to 3.89m
  • 72 x 195mm must be up to 4.44m

This is something that you can leave to a loft conversion specialist, but it is still important to take this into account when turning an old loft room into a new living area. This applies regardless of which type of loft conversion you are doing.

Other Technical Regulations

Every part of your loft work, from roof trusses to the dimensions of the hip to gable conversions, will need to follow a long list of regulations. This could be something as simple as gable wall thickness or as important as the amount of weight the floor can support.

We can take care of the regulation work, keeping you informed so that you can use your planning portal (or other tools of choice) to build a loft design that follows all necessary regulations and steps.

Is it illegal to convert a loft without building regulations approval?

Building regulations approval is vital for converting any loft space into a room that you can reliably use. Even if you just plan to use the conversion as extra space for studying rather than a full bedroom or living area, it is important to follow these regulations.

This also includes building control approval. In most cases, a building control officer will inspect the loft conversion at various stages and will point out any issues that make the loft conversion illegal or unsuitable for use as your intended space.

Types of loft conversion

With so many different types of loft conversion on the market, it is important to understand the difference while you are still creating a basic plan. Most types of loft conversion are specific types for a reason: they follow a certain design style or have a particular structure behind them.

Knowing which type of loft conversion you are aiming for can be important for getting a good idea of how to construct one. It also provides a useful frame of reference for any experts that you are calling in to take charge of the project.

Dormer Windows

Dormer windows are a small window outcrop that can be added to any existing loft extensions or roof space. These are fairly simple and provide just enough space to add a vertical window, making them a very minor form of conversion that often gets added to already-usable loft rooms.

Dormer Loft Conversion

A simple flat roof dormer loft conversion extends the original roof slope. The top of the extension roof remains flat, and the new space allows a small room (or possibly even two) to be added to the loft area.

These are suitable for any style of home and are a relatively cheap type of conversion, but they are also some of the most restrictive in terms of how flexible they can be.

Mansard Loft Conversion

Mansard loft conversions are effectively a larger-scale dormer loft conversion. These use a more vertical wall to create a much larger loft extension, giving a huge amount of additional space to your home without changing the shape of your roof structure too much.

This is one of the best ways to add an entire room to your home, complete with plenty of headroom. However, this type of loft conversion is also more expensive than dormer loft conversions and can take a lot longer to construct. They also require planning permission far more often.

Hip to Gable Conversion

A hip to gable loft conversion straightens out the side of the roof to make a vertical wall. This opens up a lot more room while only modifying part of the roof, making it smaller scale than a mansard loft conversion.

Since hip to gables are used on the sides of a house’s roof, terraced houses can’t receive them unless they are on the end of a row of terraced houses. They are also more expensive than a dormer but can be used alongside dormer loft conversions to provide even more space if you have the budget for both.

Roof Light Loft Conversion

A roof light conversion is simply the process of adding windows and a reinforced floor to the loft space. This is a cheap, effective way to turn an existing loft into a usable space – even if you also need to add sound insulation, underfloor heating, and other additional elements.

Unlike every other type of loft conversion, this does not actually add more space, meaning that you are limited by your existing roof size. Planning permission may also still be required in certain situations, and headroom requirements can force stairways to be placed in unusual spaces (such as the middle of the room).

Other Variants

Remember that these conversions are only basic types. There are countless other options, such as VELUX lofts, as well as hundreds of ways to modify each type into something new. Even so, using these general types as a guideline makes it easier to identify what kind of loft you are aiming for as a whole.

Planning loft conversions

While there is a range of loft types to choose from, finding the right one is not always easy. Before you can even get planning permission, you need some kind of plan to follow, and that is not always easy to produce from scratch.

House Type

Not all houses can receive the same loft conversions. This depends on which parts of the roof are even accessible and how easy they would be to modify.

For example, a terraced house will generally be connected to another house on either side, meaning that you can’t always add loft conversions that modify the party wall (the wall between you and the house next door). However, semi-detached houses have one party wall, allowing for more conversion options.

Loft Options

As mentioned above, there are a lot of loft options to choose from. However, some only work on certain homes, such as hip to gable conversions being ideal for semi-detached houses while not really working for terraced homes.

Existing Roof Slope

The way that your home’s roof slopes will make a big difference to the kind of conversions you can do with it. A roof’s shape is going to play a large part in the way that lofts can be converted and adjusted, especially if that shape is being held up with load-bearing walls.

For example, a hip to gable loft conversion converts sloping roofs into a vertical wall, opening up more room. However, this needs to be done in a way that works with the current roof shape, since rebuilding the entire roof is extremely expensive and time-consuming.

Space Usage

Lofts have practical limits, and even the very best structural engineer can’t always work around the limitations of a roof pitch or the amount of available space they have. Loft space has to be used carefully and planned out properly, which often forces some conversions to stay as a single room.

Each of the stud walls, roof trusses, doors, windows, access stairways, verandas, balconies, or raised landings needs to be accounted for in the design. Since many lofts also have a loft conversion type that creates a triangular space with limited headroom, using it effectively is important.

We can help you plan out the ideal way to use your new loft, making sure that absolutely no space is wasted while also not cramming the loft itself full of unnecessary details.

Get In Touch

If you are looking for loft conversions that will perfectly suit your home, our experts are some of the best people to turn to. We understand how to plan and build bespoke lofts that are ideal for each property, assisting with everything from the initial plan to the finishing touches as needed.

Contact our experts today if you want to learn more about what we can offer. We are fully equipped to take on any kind of loft conversion work, making sure to get you the planning permission you need along the way.

Other Blog Posts

Contact Our Team

Let Us Know Your Project Details

Please tick the applicable - This will help up get the best quote for you

Areas We Cover​

Loft Conversion Planning Bedfordshire
Loft Conversion Planning Berkshire
Loft Conversion Planning Bristol
Loft Conversion Planning Buckinghamshire
Loft Conversion Planning Cambridgeshire
Loft Conversion Planning Cardiff
Loft Conversion Planning Cheshire
Loft Conversion Planning Cumbria
Loft Conversion Planning Derbyshire
Loft Conversion Planning Devon
Loft Conversion Planning Dorset
Loft Conversion Planning Durham
Loft Conversion Planning East Riding of Yorkshire
Loft Conversion Planning East Sussex
Loft Conversion Planning Edinburgh
Loft Conversion Planning Essex
Loft Conversion Planning Glasgow
Loft Conversion Planning Gloucestershire
Loft Conversion Planning Greater London
Loft Conversion Planning Greater Manchester
Loft Conversion Planning Hampshire
Loft Conversion Planning Herefordshire
Loft Conversion Planning Hertfordshire
Loft Conversion Planning Kent
Loft Conversion Planning Lancashire
Loft Conversion Planning Leicestershire
Loft Conversion Planning Lincolnshire
Loft Conversion Planning Merseyside
Loft Conversion Planning Norfolk
Loft Conversion Planning North Yorkshire
Loft Conversion Planning Northamptonshire
Loft Conversion Planning Northumberland
Loft Conversion Planning Nottinghamshire
Loft Conversion Planning Oxfordshire
Loft Conversion Planning Shropshire
Loft Conversion Planning Somerset
Loft Conversion Planning South Yorkshire
Loft Conversion Planning Staffordshire
Loft Conversion Planning Suffolk
Loft Conversion Planning Surrey
Loft Conversion Planning Swansea
Loft Conversion Planning Tyne and Wear
Loft Conversion Planning Warwickshire
Loft Conversion Planning West Midlands
Loft Conversion Planning West Sussex
Loft Conversion Planning West Yorkshire
Loft Conversion Planning Wiltshire
Loft Conversion Planning Worcestershire

Contact Our Team

Let Us Know Your Project Details