Technical Booklet F2 Conservation of Fuel and Power in Buildings Other Than Dwellings·Page 41·2.79
Air barrier and insulation layer contact
The air barrier and insulation layer must be in contact to avoid thermal performance loss from air movement in cavities between them. This requirement does not apply where the space is filled with solid material such as masonry.
Significant reductions in thermal performance can occur where the air barrier and the insulation layer are not in contact with one another and there is a cavity between them that is subject to air movement. There is not a problem where the space between the air barrier and the insulation layer is filled with solid material such as in a masonry wall.
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