The house I recently purchased has a basement that has been converted into a shop and an office space. Unfortunately, proper drainage was never installed around the perimeter retaining wall to deliver water around the building. The result is that I get a water seepage through the concrete into the finished spaces in the winter time. I am planning to install a french drain on three sides of the house with an additional solid drain to carry the water from the downspouts. I know that I need to have a 12 wide strip along the house down to the drains for the drainage rock. What I need to know is what type of rock to buy. Is there a special class 1 drain rock that I should be purchasing? or will any old 1/2 gravel do? If someone could help me with this I would greatly appreciate it.