Design Guidelines for New Constructions in Historic Context

City is like a living entity، which remains constantly by constructing new buildings. In fact، city is result of different historical periods and contemporary eras are in this process، too. With few exceptions، the character of cities have chaged over time with the architectural styles fashionable in each period as well as the changing demands for their functionality. It is very rare that a place has a historic or period unity. Most often، the character is combination of styles and it is important that this evolution is maintained and the vitality of places can be continued. Our constructions will form some parts of the city in future and will cause a layer in this inherited complex، and will make specification and identity of cities and will be an inheritance for posterity. Although preservation consider as a major step in revitalization of historical sites and buildings but ironically these sites benefit from being extended. In contrary، expansion and construction of new buildings on these sites continues the history of the site to the new era and enrich its history. Now، duties of designers and their responsibility against past، present and future generations are debated. New design might involve an extension to a large and significant historic building or small historic building، a new building in a historic urban environment or a new structure at an archaeological site such as a visitor center or shelter to protect the ruins. Proposed new additions should be of a quality that will constitute a valuable contribution to the historic building، its setting and the townscape. Alterations and additions should relate to the scale and the proportions of the building and be harmonious with it. Furthermore، the interrelationships that are an integral part of the understanding of the building and its immediateenvironment should not be compromised. The immediate considerations for most designers will be the external appearance and whether it will mimic the historic or stand out as unequivocally contemporary. Neither of these two approaches is necessarily appropriate to each situation and between the two extremes lie a multitude of solutions. The purpose of this paper is to obtain principles of executive instructions for usage of designers in order to design new constructions in historic contexts. Suggested guidelines are not fixed، but they are comprehensive، thus، they can be use in different situations، and be coincided with special specifications، different conditions and hidden values in any historical fields. In order to achieve suggested guidelines، in this paper we will first analyze universal approaches and review these resolutions and concepts in this field. We will then look at the details of the agreements between the international bodies that directly or indirectly influenced these regulations and had key roles in their design. Finally we will study advices and guidance of other countries; furthermore we will debate key points and theoretical fundamentals about new constructions in historic contexts. Therefore، this guidance will offer in 5 general titles، including Character، Siting، scale، form، materials and details for new constructions.