Hi there, just had the building inspector round to look at my extension and he says the window in my daughters extended bedroom does not open enough for ventilation (it should be 5% of the square footage of the floor). i had just used the original window and put in it the end wall that had been extended out 2 1/2 metres. the floor area is 18 sq metres and the window only has an opening of 0.54 sqm. What can i do to rectify this? Not keen on changing the style of the windoe as it then wont match the rest and the plans say it has to. Thought about putting french doors in but daughter likes to sleep with the window open and i would always be worrying that she hadnt locked them. There is no way of making the room smaller. Thought about knocking another window through on the side wall, but this wall is only 0.9metres away from the boundry with my neighbour and would look onto their property. Am i allowed to do this and how would i go about it? Do i have to apply to the council?

if it is an upstairs window then you dont need planning (strictly speaking you do need a building notice) but if it overlooks the neighbour then any glazing up to 1.7m above floor level should be obscured

Thanks for that
Its a downstairs room and i just thought about putting in a window quite near the ceiling about 18" tall about 3foot wide with obscure glass so i dont upset the neighbours. who do i speak to at the council about getting this approved