Yes/no depending on what you mean by "taller than the original house":
Height of Extension
1. Where the rear wall of the house does not include a gable, the height of the walls of any such extension shall not exceed the height of the rear wall of the house.
2. Where the rear wall of the house includes a gable, the height of the walls of any such extension shall not exceed the height of the side walls of the house.
3. The height of the highest part of the roof of any extension shall not exceed, in the case of a flat roofed extension, the height of the eaves or parapet, as may be appropriate, or, in any other case, shall not exceed the height of the highest part of the roof of the dwelling.