we want to put these tiles over a flat roof but want to make sure the will not penetrate roof and cause leaks. will this work for that purpose?

Our Designer Grip-Loc Tiles are made from EVA and are a very flexible plastic that will not puncture your roof. These tiles will work as flooring on a roof. Since these tiles are not UV stable, these tiles will fade in direct sunlight. Also, there may be some expansion and contraction with these tiles, so you will want to leave an expansion gap around the flooring surface. These tiles will allow water to flow freely through the flooring system making them slip resistant when wet and they are mold and mildew resistant.