Double Brick or Inner room???

does anyone know which would be best We have a brick garage on cement slab.... would it be better to double brick the garage completely thus getting more space inside to use OR build the smaller inner room inside the garage We have the option to do both but the builder has suggested double bricking the whole garage rather then constructing an inner room... Does this sound like a good idea? cheers in advance for any opinions on this :D

IF, by "double brick", you mean simply make the existing brick walls thicker then NO. You'll get better isolation using separate inner walls, even if they're only 2 layers of gyp on frame. Try a search for mam, m-a-m, 2-leaf - this will help you get the idea of mass-air-mass construction which is better for low frequency isolation than any given SINGLE or TRIPLE mass of equivalent materials... Steve