This chapter contains key details to illustrate good practice concerning insulation placement, airtightness zones and minimising thermal bridging. The details for new build are based on cavity wall brick/block construction with concrete super-structure and include green walls. Typical retrofit junctions are based on solid brick walls. The airtightness recommendations and principles in Section 7.4 need to be applied to all of the details at both design and construction stage. For the environmental impact of different construction materials and for details of timber-framed construction, SIP, hempcrete and structural engineered timber pre-fab panels, see Section 7.2.