Thermal insulation to Walls ~ the minimum performance standards
for exposed walls set out in Approved Document L to meet the
requirements of Part L of the Building Regulations can be achieved
in several ways (see pages 478 and 479). The usual methods
require careful specification, detail and construction of the wall
fabric, insulating material(s) and/or applied finishes.
Typical Examples of existing construction that would require
upgrading to satisfy contemporary UK standards ~Thermal Insulation -- External Walls