Community Alumni
Mar 13, 2017As long as the seal is in contact with the surface then it should work no matter how much water is presented to it. Also the level shouldn't be an issue. Water won't pool up on a flat roof unless there's a depression for it to collect in. If there's a sag that's severe enough then the seal won't make contact with the lowest point. Water will just glide past. If the sag is that noticeable then I would make sure that they fix that properly since it will only get worse over time. The weight of pooled water, snow, and maybe even ice will make the depression worse over the years.