We Recently installed Wasco commerical skylites at a bank in West Newton, MA. The contractor ordered the skylites without a curb unaware that you can get a curb with it. This is fine and will work because you can build your own curb. However, the problem here is that the contractor framed it up 3 inches. We installed a tapered edge around the penetrations on our flat roofs. That means that you now only have 1 1/2 inches of curb over the roof. This is not enough curb, especially after the winter we just had, and even more so since they did not have a factory seal between the lite and curb. We ended up building curb up to eight inches which is the minimium. In the winter the snow is going to melt first at the skylites which is why it is very important to have a good seal and skylites.