I am currently starting a new extension to the rear of my property which had plans passed in 2007, the drawings from the architect show the rear wall coming off the centre of the rear pillar to a depth of 3 metres from the house, as is normal for for semi detached properties, now since the planning was approved my neighbour has erected a conservatory who's wall commences within the pillar and not off the centre of the rear pillar, I have had talks tonight with him and he has informed me that I cannot come off the centre of the pillar as it would mean my tiles would overhang into his property, the roof is going to be sloping with guttering to the rear, is he correct or is the architect correct and what if any options do I have???