These pictures are recent ones when I re-powered the roof a few months ago, but you can see how I put the rails on.
I first put on a bitumen banding flash along where the rails were going.
Then I placed a decking plastic strip on top, then the rail.
I drilled through the rail, the decking strip, the roof and into the roof trusses, 3 roofing bolts per 3m rail.
I put plenty of building silicone under the decking strip and between the decking strip and the rail.
Originally, a few of them did leak and caused wet patches to the underside but not enough for me to bother doing anything to fix it. The wet patches quickly dried out from the inside and after about 3 years the leaking stopped altogether by itself. I assume accumulation of dirt just sealed it up and its been fine ever since.
In hindsight, I think after I drilled through, I should have forced through silicone sealant through the hole from the underside and rodded it through with a small screwdriver or similar to coat all internal surfaces of the drilled hole.
