In fairness to ree, the advice about air bricks being used for ventilation of the cavity was changed later on. From W B McKay in the 30's.
' An important matter affecting the heat insulating value of a cavity wall is the extent to which the cavity should be ventilated. Formerly, it was generally considered desirable to ventilate the cavity by means of air bricks just above ground level and also at the top. Whilst this circulation of air ensured a dry cavity and reduced the risk of defects arising in floor timbers, it also destroyed the insulating value of the wall to such an extent that an 11 inch cavity wall afforded less heat insulation than a 9 inch solid wall.
Therefore the only ventilation of the cavity which is now advocated is that provided by weep holes near the best of the cavity and at the head of door and window openings'.
' An important matter affecting the heat insulating value of a cavity wall is the extent to which the cavity should be ventilated. Formerly, it was generally considered desirable to ventilate the cavity by means of air bricks just above ground level and also at the top. Whilst this circulation of air ensured a dry cavity and reduced the risk of defects arising in floor timbers, it also destroyed the insulating value of the wall to such an extent that an 11 inch cavity wall afforded less heat insulation than a 9 inch solid wall.
Therefore the only ventilation of the cavity which is now advocated is that provided by weep holes near the best of the cavity and at the head of door and window openings'.