I have a couple of sliding doors on twin tracks to put on the side of a shed about 9' high by 15' wide each. I need to work out the best way for the bottom of the doors to run. Full length channel track looks the best and most secure way? I haven't concreted outside yet so what would be the best way to fit the tracks. Setting them in wet concrete seems risky as need to get them dead level, straight and the right distance from shed edge. Pre fitting them with some sort of support/bracket seems the logical way but will be a lot of work! Any ideas/tips?