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 they are 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.
The local planning authority decides whether an application for consent is needed, and it is up to each local authority to decide whether your proposals will or will not "affect" the "character" of the building.
PPG15: Planning and the Historic Environment which indicates the sorts of things that ought to require consent, such as the replacement of windows.
May be forced to repair a listed building even if you can't afford the repairs 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.
Designed to give some protection to local areas of interest, and usually contain some listed and some unlisted buildings.
Designated by local authorities.
Substantial demolition within a conservation area requires consent.
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.
An understanding of how these differences affect the issue of maintenance and in particular the choice of materials for repairs.
A key point is to specify materials that are sympathetic to the building and compatible with its construction.
Introducing new materials might have a negative impact on the performance of the building fabric. The use of impervious or waterproof materials, even as part of a diligent maintenance or repair programme, can potentially make problems worse rather than better.
It is far better to try to retain the historic patina of an object by leaving ingrained dust, dirt and staining well alone.
Use of Portland cement for repointing and render has caused, extensive spoiling of masonry, cracking, widespread problems of moisture trapped in walls owing to the failure of Portland cement joints and the inability of render to breath.
Heat conservation, reduced maintenance, increased life of masonry materials and reduced energy consumption during manufacture are all benefits accruing from the use of lime mortars.
Contractors become involved in work which, because of lack of knowledge, they underprice and fail to carry out effectively.
Training, a system of suitable certification and the introduction of lime materials which are more user friendly.
Plants may enhance the appearance of buildings, but shrubs, trees and climbers such as ivy can damage walls or block gutters.
If allowed to grow against the base of the wall this also tends to prevent the masonry drying out properly.
Plant growth should be cleared away from the area around the base of the building and in particular from any ground gutters or drainage channels. The roots of plants and grasses can damage the integrity of such channels and impair their ability to carry water away from the building.