What is Listing?

Q. Why is my building "listed" and who decides?
A. Buildings are listed because they are judged to be "of special architectural or historic interest". The lists are drawn up by central Government on the advice of the main advisory bodies in each part of the UK (English Heritage in England, Cadw in Wales etc). A national re-listing of Welsh buildings was completed in 2005, but England has not not been extensively resurveyed since the 1980s.  Instead, more localised or thematic listings have occurred.   In 2006, English Heritage took on greater responsibility for decisions in the listing process, though a new right of appeal to government (DCMS) was also introduced.  Today there are getting on for half a million listed buildings or structures, but this is estimated to be only about 5% of the nation's building stock. Buildings are listed solely on their architectural or historic merit. Other issues such as the costs of repair or condition cannot be taken into account. But they can be considered when a listed building application is made at a later stage.
Q. Can I appeal against my property being listed?
A. Owners in England are normally now told when their building is being considered for listing and have a right to submit comments.  After a building has been listed (or rejected), owners and applicants have a right of appeal (within 28 days) or can apply for de-listing, but only on the grounds that it does not meet the current national criteria for listing or has lost the interest for which it was listed (eg through fire or damage). 
Q. Can I apply for a building to be listed ? If so, how ?
A. Anyone can apply for a building to be listed. You do not have to own it yourself. However before attempting it, remember that the building must meet the national criteria (see below). It is also worth remembering that though there were omissions, and buildings worthy of listing are still coming to light. All you have to do is write to Englsh Heritage, 1 Waterhouse Square, 138-142 Holborn, London EC1N 2ST for buildings in England; or for Wales to Cadw,  Crown Building, Cathays Park, Cardiff CF10 3NQ. Explain why you think the building is   eligible. Photos and a site location map must be enclosed. If there is any urgency, such as an  immediate threat, this should be stated.
Q. What gets listed?
A. All buildings built before 1700 which survive in anything like their original condition. Most buildings between 1700 to 1840, but some selection is necessary. After 1840 the best examples of particular building types are listed: and only those of definite quality and character. Only selected buildings after 1914 are listed. Buildings less than 30 years old are normally only listed if they are outstanding, and under threat. Buildings with important historic or technological connections can be listed even if not of great architectural merit. Individual structures, such as gateposts, milestones, and lamp posts can all be separately listed. For further guidance on listing eligibility in England see English Heritage's Principles of Selection for Listing Buildings.
Q. What are the different Grades?
A. In England and Wales there are three main Grades - I, II* (known as two star), and II. In Scotland the grades are A, B, B(group), C. In Northern Ireland A, B+, B.
Only about 3% of listed buildings are Grade I (the most important grade); a further 5% are II* (and therefore special in some way); while the remaining 92% are Grade II. The grade has nothing to do with the size or date of the building. A vast mansion can be Grade II; a small farmhouse Grade I.
Q. What does listing cover? 
A. A very common mistake is that the Grade determines what is legally protected. It is often said, totally wrongly, that only the front elevation of a Grade II building is covered. Or that a building contains "a listed staircase", for example (there is no such thing, though that might be the main reason the building was listed). Whatever the Grade, listing covers the entire building, inside and out. Other structures within the curtilage of (land surrounding) the building may also be included.
Q. Does listing stop me changing my building?
A. Listing is not a 'preservation order' that stops all change. On the contrary it is simply a marker that the building is special and that before changes are made they must be assessed by the local authority, and for more important buildings by English Heritage or its equivalent. Contrary to popular belief the majority of listed building applications are approved.
Q. What work needs listed building consent ?
A. Consent is needed for "works for the demolition of a listed building or for its alteration or extension in any manner which would affect its character as a building of special architectural and historic interest."
Q. What does that mean in practice? Is there a list of proposed changes that need consent?
A. It is impossible to give a universal answer. This is because it is the local planning authority which decides whether an application for consent is needed, and it is up to each one to decide whether your proposals will or will not "affect" the "character" of the building. There are hundreds of different planning authorities, so the answer may vary from one district to another. However they do receive guidance from central Government. In England there is a document called PPG15: Planning and the Historic Environment which indicates the sorts of things that ought to require consent, such as the replacement of windows. However this is only advisory. You should always start by talking to your local conservation officer (in the planning department) or other relevant planning officer about what you have in mind before going as far as a formal application. They should steer you away from proposals that are certain to be refused, and may well be able to indicate acceptable ways you can achieve what you want.
Q. How do I make a listed building application?
A. Your local planning office can advise you, but you will need to fill in a form. Professionally prepared drawings are likely to be needed. There is no fee for submitting a listed building application, though there will be one for a separate planning application if it is required.
Q. If my application is refused, can I appeal?
A. Yes. The local authority will tell you how to, but for an appeal you will have to have the proper grounds.
Q. Can I be forced to repair my listed building even if I can't afford it?
A. Yes, but only if the building is decaying very badly. Local authorities have two main powers to halt the deterioration of a listed building - the serving of an urgent works notice or a repairs notice. In practice many local authorities have never issued either.
Q. What if I carry out works without listed building consent?
A. Unauthorised demolition of all or part of a listed building is a criminal offence and can lead to prosecution. If the local authority discovers unauthorised work in progress, it can put a stop to it and invite the owner to apply retrospectively for consent. Alternatively the local authority can take enforcement action, requiring you to put back some damaged feature or fabric.
Q. What other permissions might I need to work on my house?
A. Depending on what you propose, and how you use the building, you may well need planning permission in addition to listed building consent, and approval under building and fire regulations. For example, Part L of the building regulations has requirements relating to energy efficiency. Some of the regulations are potentially harmful to historic buildings and there may be some degree of discretion in how they are applied. Buildings open to the public need to comply with the Disability Discrimination Act, but the law does not over-ride listed building controls.
Q. My house is in a conservation area. What does that mean?
A. Conservation areas are designed to give some protection to local areas of interest, and usually contain some listed and some unlisted buildings. They are designated by local authorities. Substantial demolition within a conservation area requires consent. In addition certain "permitted development rights" that apply to domestic buildings are reduced in conservation areas, so planning permission is needed for changes such as the installation of dormer windows on the front of a roof. You will also need permission to lop or fell trees. Sometimes a local authority will use an Article 4 Direction to remove "permitted development rights" and this brings tighter controls. New development in conservation areas is also more strictly controlled than normal.
Q. Can my garden be listed?
A. Only historic structures within it. There is a statutory register of important parks and historic gardens, where extra planning constraints apply, but there is no equivalent of listed building consent.
Q. What is a scheduled ancient monument?
A. The laws protecting scheduled ancient monuments are generally the most demanding. Many monuments are buried sites but some are standing structures, ruins, or unoccupied buildings. The majority are in private ownership. Almost any work to them requires the consent of the relevant Secretary of State. But there are no powers to force the owner of a scheduled monument to halt deterioration or carry out repairs, which is why a substantial number are at risk.
Q. Is it true that churches and chapels do not have to apply for listed building consent?
A. It depends on the denomination. Most of the main denominations enjoy what is known as "the ecclesiastical exemption", which applies to listed buildings used for worship. This means they do not have to apply for listed building consent because they have set up their own broadly equivalent systems of control (however they do still need to seek secular planning permission for works such as extensions). Others religious bodies, such as The Society of Friends, mosques or synagogues, have opted to come under normal listed building control where they own historic buildings.
The most elaborate system of control is that of the Church of England (and in Wales). This functions under ecclesiastical law. Works to churches require a permission known as a "faculty". Each application is considered by an expert body known as the diocesan advisory committee, and their recommendations are put to a senior legal figure known as the Chancellor, who takes the final decision. A faculty is likely to be more detailed than a listed building consent - for example, stipulating the mix of lime plaster to be used.
English Anglican cathedrals do not come under the faculty system, but under the Care of Cathedrals Measure. Works to them are approved by a local fabric advisory committee, while more major changes are referred to a national body called the Cathedrals Fabric Commission for England, with formal consultation of bodies like the SPAB.

Further Information
Historic Building Controls and Grants, SPAB Guide II by Matthew Slocombe
Listed Buildings, Conservation Areas and Monuments, Charles Mynors Sweet and Maxwell 2006 ISBN:0421758309
It is well worth contacting your local conservation officer at your local council for help and advice. Though conservation officers are overworked, they will normally try to guide you through the system. Many planning departments have useful, and generally free, leaflets about listed building matters. Some include guidance on subjects such as window replacements, repointing etc.