Which adhesive caulk for solar panel mounts??

mrdon2 wrote:
The attachment shows the roof prints to help you find the cross members to screw into.

Finding stud centers may take some patience.

I had roof prints from my trailer manufacturer, they only served as a rough indication of rafters location. Wooden rafters are narrow 1.3/4" so I needed accuracy +/- 0.5" or better. Prints showed the layout from the inside, i.e. looking from the room, not looking from above. Say, print shows the distance to rafters from the wall and it is unclear whether it is from the inside panel or whatever. When you are on the roof, there are no reference points other than curvy lines of exterior trim, and the roof itself is arched.

So drilled 1/64" pilot hole and passed a thin stainless wire to see if there really was a rafter where it should've been, and where the edges and centers are. Few times the hole was close to the edge and had to be abandoned, plugged and sealed, it's just a tiny 1/64" hole, and another hole was drilled. My brackets were home-made, aluminum, big footprint each bracket, 3-5 screws per bracket, and there was enough room to correct a mistake and drill another hole. Off the shelf brackets are too small to drill another hole next to the first one, or - worse yet - they are plastic.

In motorhomes the cross-members could be metal but I'm not sure they are wider than 1.3/4", so you'll need same accuracy.