Cast Iron Air Bricks vs Clay Air Bricks
In the photograph above we’re comparing our GRID6 9×6 air brick with a similar sized clay air brick. If we take, for example, the corresponding 9×6 clay air brick in the photograph top right (middle of the 3 air bricks shown in buff) and compare the free air flow we can see a huge difference in ventilation supplied between these two products.
The clay air brick is inefficient as a ventilator because it requires a substantial amount of material to prevent it from deteriorating during winter months and succumbing to frost damage which leaves little room for holes – the main purpose of an air brick! We can see that the clay 9×6 air brick has small 8mm square holes in just four rows and nine columns which allows for a free area in mm2 of 8x8x4x9 = 2304mm2
The cast iron air brick, however, isn’t affected by frost and therefore can be made with much larger holes, smaller ribs and narrower borders therefore allowing for substantially more ventilation holes and creating a very efficient vent. The cast iron 9×6 air brick has larger 11mm square holes, in twice as many rows (eight) and an impressive thirteen columns which allows a free area of 11x11x8x13 = 12,584mm2
The standard cast iron air brick provides more than 5 times the ventilation of the same size clay or terracotta air brick . If even more ventilation is required, our MAX6 maximum flow air brick of the same size will provide 18,000mm2 free area – an even more impressive vent! http://www.castironairbricks.co.uk/product/max-6-air-brick/