Imperial air bricks are about the size of a Victorian brick which is around 9 x 3 inch or 225 x 75mm. They are quite a bit smaller than a metric air brick which is 8 ½ x 2 ½ inch or 213 x 66mm.
The Cast Iron Air Brick Company have therefore designed an aluminium adapter to convert the metric duct so it will engage with many of the imperial air bricks we have.
We call the adapter the metimp the name which conveniently translates to metric imperial.
It is essential to use the adapter to connect all our 9x3 air bricks to metric ducting where the air brick doesnt have a cutaway frame. Please see the specification guidance for full details of each design.