Yes you do need trickle vents

England / Wales

Yes, your products will require trickle vents. In habitable rooms and kitchens, a min. of 8000mm2 equivalent area is required per room (10,000mm2 in single story dwellings). Bathrooms (with or without a toilet) require a min. of 4000mm2.

Scotland

Yes, your products will require trickle vents. Generally, a min. of 10,000mm2 equivalent area is required per room (12,000mm2 in apartments). However, where infiltration rates in a dwelling exceed 10m3/h/m2 @ 50 Pa, which may often be the case in existing buildings, the ventilation required may be reduced to 8000mm2 for apartments and 4000mm2 for all other rooms. Alternatively, the overall provision of trickle ventilation in a dwelling may be provided at an average of 6000mm2 per room, with a minimum provision of 4000mm2 in each apartment.