The other difficulty is that 8,000mm2 is a big area for trickle vents- I've fitted 2 to my new upstairs window and I don't think they're enough to meet the requirements. Downstairs I have aluminium bi-folds so I've fitted a louvre and air brick above:
I find it odd that the requirement is the same, for a 4sqm box room or a 40sqm open plan extension!
I find it odd that the requirement is the same, for a 4sqm box room or a 40sqm open plan extension!