Hi all - I'm proposing to build a timber car-garage (24' x 10') on clay soil. I'm advised to lay a 6" subbbase of hardcore or Type 1 (which are quite different size/grading) with 4-6" of concrete on top. Also, to lay a damp proof membrane, either on top or beneath the subbase. With this structure, is a subbase necessary and is Type 1 preferable? Is the subbase to disperse load or drain water (or both)? And is a DP membrane really necessary, is rising damp likely to be a problem? If so, is membrane best above or below subbase? I've been asked (by the company who will erect the garage) to lay a single course of engineering bricks around the perimeter, just a couple of inches inside the edge of the concrete - would several inches be better to prevent possible edge cracking? Do I need any reinforcement or mesh in the concrete base? Any advice greatly appreciated. Thanks.