when did cavity wall insulation become part of building regulations
Cavity wall The typical cavity wall method of construction was introduced in Northwest Europe during the 19th century and gained widespread use from the 1920s. In some early examples stones were used to tie the two leaves of the cavity wall together,[3] while in the 20th century metal ties came into use. Initially cavity widths were extremely narrow and were primarily implemented to prevent the passage of moisture into the interior of the building. The widespread introduction of insulation into the cavity began in the 1970s with it becoming compulsory in building regulations during the 1990s.[clarification needed]
Berlin Wall The "fourth-generation Wall", known officially as "Stützwandelement UL 12.11" (retaining wall element UL 12.11), was the final and most sophisticated version of the Wall. Begun in 1975[73] and completed about 1980,[74] it was constructed from 45,000 separate sections of reinforced concrete, each 3.6 metres (12 ft) high and 1.2 metres (3.9 ft) wide, and cost DDM16,155,000 or about US$3,638,000.[75] The concrete provisions added to this version of the Wall were done to prevent escapees from driving their cars through the barricades.[76] At strategic points, the Wall was constructed to a somewhat weaker standard, so that East German and Soviet armored vehicles could easily break through in the event of war.[76]