I am in the process of a small extension to my 1930's semi which is basicly extending my dining room a couple of metres level with the end of the kitchen. My question is, when the external wall is knocked out, what would the minimum the wall can stick out to carry the lintel. I have been informed that it needs to be 450mm either side with a bearing length of about 200mm. one side is the neighbours and the other side is the corner where the kitchen then sticks out. The width of the room is about 3.5m wall to wall. If it has to be 450mm it is going to seem like the extension is another miniscule room. Can this 450mm dimension be made much smaller and if so what is needed to be done to hold the strength please.