The simplest and most cost efficient loft conversion of all. With significantly less construction work than other forms of loft conversion offers a way of increasing the size of your home for minimal cost.
Velux windows allow for a bright and airy loft conversion and can also incorporate rain sensors, which automatically close if rain is detected. This type of loft conversion is usually covered under permitted development.

A dormer style loft conversion is a way of increasing the headroom and floor space in a loft conversion by extending the roof out vertically from the existing sloping roof and will incorporate either a sloping or flat roof. Rear dormer loft conversions usually fall under permitted development and are suitable for pretty much all types of property.

Mansard Loft conversions are a type of loft conversion that is very popular with properties in London. A mansard is a roof style requiring the reconfiguration of the rear slope into a flat roof that extends from the existing ridge and slopes down at around 70 degrees, offering a maximum increase in headroom and floor space. For properties with a duel pitched roof it is possible to have “L” shaped mansard offering even more room from a loft conversion. Mansard loft conversions almost always require planning permission due to large alterations to the existing roof structure.

Hip to gable style loft conversions require the side sloping roof known as the hip roof of a semi or detached property to be reconfigured into a gable wall with an extension of the existing ridge to form an ordinary pitched roof.
This type of loft conversion may incorporate a rear dormer or simply be turned into a Velux Room. Hip to gable loft conversions are typically covered under permitted development provided the plane of the roof on the principle elevation is not altered

The UK planning system exists to retain our heritage while allowing for the improvement of our towns, cities and countryside. Parliament controls national planning policy, but your local authority is responsible for deciding whether or not a development should go ahead.

If you wish to carry out certain building work you will need to seek permission from the planning department of your local authority. It is your responsibility to seek planning permission and, if required, approval should be granted before work begins.

If in doubt, always check with your local authority.
If you live in a Conservation Area or own a Grade 1, 2 or 2* listed property you will be subject to further conditions that will be set out by your local authority or regulatory bodies such as English Heritage. If in doubt, always check with your local authority.

How long will it take to get planning permission?
A typical planning application for an extension or a loft conversion should take 8 weeks. This is the time limit set out by central government that local authorities have to stick to, although this rises to 13 weeks for complex applications.

It is important to consider the time you will need to assemble your planning application. You will need to:

It is important to consider the time you will need to assemble your planning application.

Survey your home and prepare accurate drawings of the existing property and your proposal for development
Support your application with a ‘Design Access Statement’ that demonstrates you have considered the form, proportion, layout, volume, materials and impact of your proposal with the guidelines set out by your local authority
Allow 4-10 weeks, as you will be making important decisions that you will have to live with for some time. In total, from the initial design work to the decision on your planning application, the time frame could be five months or longer.
What will help my application to be approved?
The key factors taken into consideration are:

NEIGHBOURS and whether they raise any objections

DESIGN specifically the quality of design and whether it is in keeping with surrounding properties

IMPACT of the layout, size and volume of your proposal and whether it impacts detrimentally on your neighbours through loss of light, amenity or privacy

When the planners are considering your application, it’s not enough for you and your neighbours to be happy with the proposal. Planners take future owners of the property into account and consider the wider impacts of your proposal within their own Local Development Plans.

The trouble with planning permission
It’s subjective. You are mostly at the mercy of the planners. If they don’t agree with your proposal, it will be refused – even if you feel that you’ve met the criteria set out in their design guidelines and can demonstrate that there are similar developments within your immediate area.

It’s piecemeal. Most local planning departments are over-burdened and don’t have the time to provide you with adequate pre-planning advice. High turnover of staff (we have a national shortage of qualified planners) creates major problems, especially if your planning officer leaves mid-way through the application process.

Keeping neighbours up to date in person is a great way of minimising written objections to your application.

It’s emotional. Keeping neighbours up to date in person is a great way of minimising written objections to your application. There is nothing neighbours hate more than first hearing about your development plans from the council. This is often more down to concerns about noisy builders than the aesthetic merits of your proposal.

When raising money to fund your project it is standard practice for lenders to request evidence of planning permission before releasing the full funds.
If you want to sell your property, you’ll need to demonstrate to your buyer’s solicitor that you have carried out your improvements in accordance with the relevant planning laws.
Work carried out without planning permission will often have to be taken down if the local authority finds out.
Permitted development
Certain minor changes to your property may be covered by Permitted Development. If the work you plan to carry out falls within certain guidelines then you do not require planning permission.

Understanding the Building Regulations
The Building Regulations are extensive and approval is required for most building work in the UK.

What are the Building Regulations and Building Control?
The Building Regulations are grouped in to categories A (structure) to P (electrical) and exist to ensure the health, safety, welfare and convenience of people in and around buildings, as well as the water and energy efficiency of buildings. The main function of Building Control is to ensure compliance with Building Regulations.

What is the Party Wall Act 1996?
The Party Wall Act 1996 is legislation controlling building work that affects a wall, fence or any part of your neighbour’s structure. You’re not required to consult with neighbours under building regulations, but you may be required to issue a Party Wall Notice. It is advisable to consult with a Party Wall Surveyor before starting any building work.

When do I need Building Regulations approval?
Building work as defined in the Building Regulations will normally need approval from a Building Control Body.

Examples of the type of works that need approval from a Building Control Body:

Loft conversions
Garage conversions
Cavity wall insulation
For work involving the installation of certain types of services and fittings, tradesmen who are registered with a Competent Person Scheme are able to self-certify their work. This means that you won’t need to separately notify a Building Control Body.

responsibility ultimately lies with the building owner, who may be served a notice if work doesn’t comply with the Building Regulations

Whoever carries out the building work should be responsible for ensuring that the work is compliant with the Building Regulations. However, responsibility ultimately lies with the building owner, who may be served a notice if work doesn’t comply with the Building Regulations.

Use one of the following Building Control Bodies (BCB) to get Building Regulations approval:

Your Local Authority Building Control office. Building Control applications can be submitted to your local authority online via Local Authority Building Control (LABC).
Approved Inspectors are private sector companies who are approved to carry out the Building Control service instead of your local authority.
For certain minor works, tradesmen and builders belonging to a Competent Person Scheme can self-certify that their work complies with Building Regulations.

If you use a Local Authority Building Control office there are three types of pre-site application:

Full plans where drawings and other related information are submitted and a formal decision is given.
Building notice where minimal information is submitted and no formal decision is given. Work is inspected while in progress and approved on completion.
Regularisation where retrospective approval is sought for work carried out without Building Regulations approval.
Once work is underway, the Building Control Service will need to make routine site inspections at various stages. Notice should be given to allow Building Control adequate time to inspect the work. If suitable notice isn’t given, Building Control may ask for work to be opened up for inspection. Talk to your local Building Control Service for more information about the inspection process.

If you use an Approved Inspector you should jointly notify your Local Authority that an Approved Inspector is carrying out the building control function.

If you use a tradesman who belongs to a Competent Person Scheme they will self-certify their work and notify Building Control.

If your building work doesn’t comply with Building Regulations you may be subject to enforcement notices and fines.

If your building work doesn’t comply with Building Regulations you may be subject to enforcement notices and fines. If your local authority considers that the building work doesn’t comply with Building Regulations, they won’t issue you with a completion certificate. Unless work is rectified, any contraventions will appear in local land searches if you sell your property.

Competent Person Schemes were introduced by the Government to allow individuals and businesses to self-certify that their work complies with the Building Regulations. Competent Person Schemes are an alternative to submitting a building notice to Local Authority Building Control or using an Approved Inspector.

Tradesmen who are registered with a Competent Person Scheme are vetted to ensure they are qualified to carry out specific types of work

Tradesmen who are registered with a Competent Person Scheme are vetted to ensure they are qualified to carry out specific types of work in accordance with the Building Regulations. Scheme members are normally covered by warranties and you should have access to a complaints procedure if work is not compliant.

Registered tradesmen will notify Building Control on your behalf and issue you with a certificate of completion. If you don’t use a registered tradesman then you will have to notify Building Control and pay a fee to have the work inspected.

New installation or replacement of a heating system or any boiler
New installation or replacement of an oil tank
Alterations to existing plumbing/electrics in kitchens or bathrooms
New electrical installations in bathrooms, kitchens and outdoors
Installation of fixed air conditioning systems
Installation of additional radiators to an existing heating systems
Replacement window and door units
Loft conversion
HomeLoft conversion
Planning Permission
Planning permission is not normally required. However, permission is required where you extend or alter the roof space and it exceeds specified limits and conditions.

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:

A volume allowance of 40 cubic metres additional roof space for terraced houses*
A volume allowance of 50 cubic metres additional roof space for detached and semi-detached houses*
No extension 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.
*Bear in mind that any previous roof space additions must be included within the volume allowances listed above. Although you may not have created additional space a previous owner may have done so.
**Designated areas include national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.

Loft conversions mini guide

Access our interactive guide to the planning permission and permitted development regimes for loft conversions.
Please note: the permitted development allowances described here apply to houses not flats, maisonettes or other buildings. View guidance on flats and maisonettes here.

Permitted Development for householders – Technical Guidance
You are strongly advised to read a technical guidance document produced by the Government to help understand how permitted development rules might apply to your circumstances.

Download ‘Permitted development for householders – Technical guidance’
Protected Species

Work on a loft or a roof may affect bats. You need to consider protected species when planning work on this type. A survey may be needed, and if bats are using the building, a licence may be need.

Building Regulations

Building regulations approval is required to convert a loft or attic into a liveable space.

This section provides guidance for making alterations to the loft space of an existing house which is no more than two storeys high. Requirements for alterations to an apartment or other dwellings like maisonettes, or houses over three storeys, will be similar but may be more extensive and possibly extend to other parts of the building.

The regulations will be applied to ensure, for example:

the structural strength of the new floor is sufficient
the stability of the structure (including the existing roof) is not endangered
safe escape from fire
safely designed stairs to the new floor
reasonable sound insulation between the conversion and the rooms below.
You may wish to make these alterations to enhance the storage facilities available or to increase the living space of the home. If you plan to make the loft space more accessible or more habitable by, for example, installing a stair to it and improving it by boarding it out and lining the walls / rafters etc, more extensive work is likely to be required and the Building Regulations are likely to apply.

It is recommended that you contact Building Control to discuss your proposal and for further advice and you must also find out whether work you intend to carry out falls within The Party Wall etc. Act 1996.

Boarding-out for storage
In most homes, the existing timber joists that form the “floor” of the loft space ( i.e. the ceiling of the rooms below) will not have been designed to support a significant weight (known as “load”). The joists tie the pitched members of the roof together to prevent them spreading and support the ceiling lining of the rooms below.

An excessive additional load, for example from storage, it may mean that the joists are loaded beyond their design capacity. If you decide to lay flooring boards over the existing joists in the loft space, then this may require a Building Regulations Application to Building Control. Your local Building Control body will be able to advise you on this issue.

Creating a liveable space
If you decide to create a liveable space (a ‘livable space’ is where you intend to use the room as a normal part of your house, this includes spare bedrooms which may be used infrequently) in an existing loft space of a home it is likely to require a range of alterations.

Many of these could have an adverse impact on the building and its occupants if they are not properly thought out, planned and undertaken in accordance with the requirements of the legislation.

Further Information
The following pages give an indication of some of the elements normally required to satisfy the requirements of the Regulations when converting a loft:

Existing walls & foundations
New Dormer
New internal elements
Fire safety
The following common work sections give an indication of several other elements normally required to satisfy the requirements of the Regulations when converting a loft:

Doors and windows
External walls
Kitchens and Bathrooms
Internal walls
Existing walls & foundations

Load bearing walls
With regard to the structural stability of the existing walls when undertaking a conversion of a loft space, consideration will need to be given as to how the new loads will be supported. For example, if new floor joists are provided and they are to be supported by an existing wall, the wall will need to continue all the way down through the house to a foundation or alternatively the wall will need to be provided with an adequate intermediate support.

Existing openings
Some houses have through lounges on the ground floor where the existing load-bearing wall that did take a load down to the foundation has been removed, or it may have originally been built as a through lounge, with a steel/timber beam installed over the opening. This beam should be checked that it is strong enough to carry any new loads from the loft conversion are added.

Existing foundations
Generally the additional load (weight) from construction and use of the new loft room(s) does not mean a significant increase on the load being transferred to the foundations.

However, in some cases, the increase in load could be significant and the adequacy of the existing foundations to carry this extra load will need to be checked. It may be necessary for the capability of the foundations to be increased by underpinning them. A structural engineer or your Building Control Body will be able to advise you.

New Dormer
A dormer is generally constructed from timber. The main parts that form a dormer are the roof, side walls (cheeks) and front wall which faces the garden. The cheeks can be supported in one of two ways:

The rafters can be doubled and bolted together with the cheeks then constructed off the rafters.
If the dormer width means the cheeks are at the edges of the roof then the cheeks can be taken down to the floor and supported of the floor joists (which are doubled) or on a beam, or in some cases by the party or external walls.
Dormer Walls
The front wall of the dormer can be supported off the external wall, or if it is to be set back from the external line of the house, it can be supported off the new floor joists, which should be designed to cater for the extra load of this wall (see also external walls).

The dormer may well need to be constructed so as to give resistance to a fire spreading to or from a neighbouring property – the nature and extent of the construction to give this fire resistance will be dependant on the size of the dormer cheek and its proximity to the boundary.

Removal of rafters
To enable a window, rooflight or dormer to be installed when creating new room(s), it is normally necessary to cut an opening in the existing rafters.

The remaining sections of the cut rafter(s) can be supported by the new dormer or, in the case of a new window/rooflight, will need to be supported by installing new timbers (known as trimmers) across the head (top) or sill of the new opening.

Depending on the size of the new opening, these may need to be two timbers fixed together (double trimmer) so that they can adequately transfer the load to the existing rafters on either side of the new opening.

It generally good practice to strengthen the rafters on both sides of the opening as they are now taking more load. This can be achieved by bolting another rafter of the same size and length to the existing.

New internal elements
The new elements which help to form the new loft room(s) are broadly:

Floor & beams
Floor & beams
It is unlikely that the existing ceiling joists will be adequate to support the weight (loads) that arise from the construction, contents and use of a typical habitable room developed in a loft.

To overcome this problem new floor joists would need to be installed to take these new loads. These can normally be placed between the existing ceiling joists and will probably be larger than the existing joists. If the existing walls are adequate then the new floor joists may be supported on them.

Otherwise additional support – such as steel or timber beams – should be introduced which in turn will be required to be adequately supported and provided with fire resistance.

New walls will contribute to the perimeter of the new room(s) and will help support the existing and new roofs where existing roof supports have been removed. Such new support for the roof will normally take the form of low level walls towards the eaves of the premises, helping to reduce the span (unsupported length) of the existing rafters. Other walls, typically loadbearing, will separate the new room(s) from other areas of the home. These walls may need to be fire resisting.

Sound Insulation
Sound insulation 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. If they think it is necessary the building control body also ask for a test to be carried out, but this will depend on the neighbours allowing access for the testers. The existing party wall will need to be upgraded to provided sound insulation between the properties.

Fire safety

Loft Conversions
When converting an existing roof space into a room or rooms the provisions for escape need to be considered throughout the full extent of the escape route. This often means that additional fire protection will be necessary in the existing parts of the house.

For example, a typical loft conversion to a two-storey house will result in the need to provide new fire-resisting doors and sometimes partitions to protect the stairways. This is because it is too dangerous to escape via windows from floors above first floor level.

Mains powered, interlinked smoke alarms will also need to be provided within the stairway at each level.

It may also be necessary to upgrade the fire protection to some parts of the structure of the house such as the floors.

You may also wish to consult ‘Approved Document B (Fire safety) – Volume 1: Dwellinghouses (2006 Edition)‘ .


Fire & general safety
To ensure adequate fire safety for the dwelling a new stair serving the new room(s) will be needed. Where there is not enough room for a full traditional stair, it may be possible to use a “space saving” stair. Retractable ladders or stairs are not normally acceptable.

For general safety reasons, there are specific criteria that a stair should be designed to.

Opening for new stairs
This would normally be formed by cutting away some of the existing ceiling joists between the existing habitable areas of the home and the loft-space. As these joists support the existing ceiling and restrain the pitched roof from spreading, replacement support should be provided. This would normally take the form of timber “trimmers” around the opening, most likely to be at least two timbers fixed together (double trimmer) to ensure the load is transferred to remaining timbers.