Building regulations state that rooms need a certain amount of ventilation, some more than others. Ventilation can be provided for via several methods. One method is the use of trickle vents in timber windows. We don't fit them as standard so you will have to tell us that you need them. The first photo below shows the internal view of a trickle vent. The second photo shows the external view of a trickle vent which is hidden behind a drip. Trickle vents can be opened or closed. They are handy for rooms where ventilation is needed without having the security risk of leaving a window open. Trickle vents come in differing sizes and give different amounts of ventilation so you will have to ascertain what size you require from your local building control. We charge £15 per trickle vent for the type in the photo below. There are larger trickle vents available which would need a larger head on the frame. As trickle vents are not aesthetically pleasing and sometimes not necessary, people often opt not to have them. If you have opted for multipoint locking, this has a night vent feature which you may consider to be satisfactory. If there are no trickle vents needed, the head will remain solid.