Our house will have a natural stone finish and we have a predicament regarding the proposed wall thicknesses. The overall thinkness of the external walls will be large i.e. approx 665mm!!! This is made up of a 215mm inner leaf block, 150mm cavity, 100mm outer leaf block and 200mm natural stone. I am concerned this is excessive, will not look right and will reduce the amount of daylight that will penetrate. My architect has designed a 215mm inner leaf. He has described his reason for this as being due to the 'span' in the rooms and the size of the house. (Not really sure about this so maybe someone could clarify.) I was originally looking at using a 200mm cavity but this would leave the walls even thicker. Opinions & advice would be appreciated. Surely this is common when using stonework on houses.