What is the minimum requirement for height where the pitched ceiling meets the walls. I have a funny suspicion that it should be 1.5m head height but from what i can see on finished loft conversions on the net this seems to be a lot lower than 1.5m. Also will I require planning permission to carry out the work. There will be velux windows put in in the front elevation so i suspect this may require planning permission. Or does it as it may still be permitted development therefore I only have to gain building warrant. Also do I have to vent the additional rooms in the attic or will a velux be sufficent?