<P> 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 , 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 . </P>
<P> 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 , 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 . </P>
when did cavity wall insulation become part of building regulations
when did cavity wall insulation become part of building regulations
1990s
1990s