Background and Purge ventilation of an inner room

[Eddman]

Hey guys - hoping to find some real world guidance!
I am designing an extension on the back of a house. They want to keep the existing back living room as a seperate room from the extnsion room but there is no external wall in the now inner room to put a brick vent to external air. We are going to have doors between inner room and new extension for purge ventilation.

Is it possible to run an airbrick type arrangement through the roof to provide background ventilation? It is a bungalow with no room in the loft.

So i mean a vent grill in the ceiling of the inner room with ducting up to a vent tile in the roof with a grill to allow air to passively enter and exit the room - will this satisfy building control?

 

[Scally-Ho]

IMO the definitive answer will depend on your area building control. Permaguard might be able to advise you.

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[^woody^]

You need to look at Part F as there are criteria for purge and background ventilation depending on combined floor areas. There may be a requirement for a minimum permanent opening between the rooms too.

And don't forget fire safety for inner rooms. That's more onerous to acheive.

 

[Eddman]

Thanks both, I am trying to get hold of my local building control officer to ask.
Woody - i am trying to bypass the permanent opening between the rooms as the homeowner wants to put doors in - hence asking if the way to achieve background ventilation is possible through a passive vent taken through the roof rather than through an external wall (as there are no external walls in the inner room).

 

[^woody^]

You'll need to review Part F to see what the air changes per hour or litres per second are required, and if your alternative acheives it.