Can full-fill cavity insulation be used in areas affected by wind-driven rain?
There is a bit of a popular myth that full-fill cavity wall insulation (any application where the cavity void is less than 50 mm) is banned on properties in a Very Severe risk area. In reality, this only applies in Scotland where the Technical Handbooks to the Building Standards recommend that full-fill insulation is used only in areas classed as Sheltered
whilst the NHBC standards states it is not permitted to use full fill insulation at the time of construction
. Additionally, pumped/blown thermal insulation cannot be used to fully full cavities of properties in Northern Ireland or the Isle of Man at the time of construction.
In most other areas, specific full-fill solutions can still be used providing the construction meets local Building Regulations. The NHBC also provides its own guidance for suitable wall constructions for use with full-fill cavity insulation in England, Wales and Northern Ireland (where the external leaf does not exceed a height of 12 m) within table 2 of Chapter 6.1 of the NHBC standards.
The requirements for new homes are shown below: