I hope some of the engineers/archs who post here can advise. I have actually asked my engineer but it will take him weeks to come back to me. When we built our house we added on an extension within the limit exemption- think it was 25m at the time. We used this extension downstairs as a part garage/ part dining room and upstairs a bathroom. Now I want to convert the garage/dining room into one big sitting room. As it was never part of the planning anyway do I need to get planning permission for this? If I need to get planning permission I am thinking of going ahead and doing the work and applying for retention ( I am fairly confident that no one would object and that council shouldnt have a problem with conversion of an existing structure) but originally our planning permission said we had to have wooden sash windows. Would that mean that if I put in french doors to the garage door that they should be wooden too? I like wooden but we live by the sea so the upkeep will be disastrous. We actually had aluminium cladded wooden sash windows to the rest of the house with planning approval but I am not keen to have to buy similar french doors because they will cost €5000.00. Would appreciate advice.