Building with a light structure or framework, in particular with a metal or wooden framework, comprising lateral walls and a roof and forming a closed enclosure, all of the lateral walls of the building consisting of a wall device comprising: - a primary framework formed by discrete elements, in particular made of metal or wood, forming part of the framework of the building, - surface elements of the panel or board type fixed onto the primary framework and forming a continuous wall structure forming a barrier between the internal and external environments, - a thermal insulating layer, - an additional layer forming a continuous lining that is watertight, substantially airtight and permeable to water vapour and - a layer of cladding and skin possibly composed of individual cladding elements or portions of skin supported by a secondary framework, said layer of cladding forming the outer face of the wall, the roof being formed by a continuous supporting wall structure covered by an insulating and sealing complex (12, 12') and the lateral walls of the building forming with the roof an overall enclosure of the building that is watertight, airtight and permeable to water vapour, said building being characterised in that - the layer of thermal insulation is applied onto the outer surface of the continuous wall structure, - said addition layer is on the one hand formed by strips of flexible lining, of low thickness, with a thermoplastic material base, having an increased water tightness, a high degree of airtightness, high permeability to water vapour and joined together by continuous welding with a simple caloric intake, without additional means or substances, for example by hot air welding, at the level of lateral portions of mutually overlapping strips (7"') and on the other hand applied onto the face directed towards the outside of the thermal insulating layer with a relatively rigid constitution and - said insulating and sealing complex (12, 12') comprises underneath a water vapour lining connected in a continuous and sealing manner to said additional layer. - a primary framework formed by discrete elements, in particular made of metal or wood, forming part of the framework of the building, - surface elements of the panel or board type fixed onto the primary framework and forming a continuous wall structure forming a barrier between the internal and external environments, - a thermal insulating layer, - an additional layer forming a continuous lining that is watertight, substantially airtight and permeable to water vapour and - a layer of cladding and skin possibly composed of individual cladding elements or portions of skin supported by a secondary framework, said layer of cladding forming the outer face of the wall, - the layer of thermal insulation is applied onto the outer surface of the continuous wall structure, - said addition layer is on the one hand formed by strips of flexible lining, of low thickness, with a thermoplastic material base, having an increased water tightness, a high degree of airtightness, high permeability to water vapour and joined together by continuous welding with a simple caloric intake, without additional means or substances, for example by hot air welding, at the level of lateral portions of mutually overlapping strips (7"') and on the other hand applied onto the face directed towards the outside of the thermal insulating layer with a relatively rigid constitution and - said insulating and sealing complex (12, 12') comprises underneath a water vapour lining connected in a continuous and sealing manner to said additional layer.