I have a small upcoming job on a "commercial strip mall" type building where the siding is that sort of corrugated metal flashing, with the reinforcing ribs about 8" apart. Apparently underneath is no sheathing; the flashing went right onto the framing. Finding the studs isn't that hard as we can literally push on the flashing to feel for them, and we plan to use standoff straps for the horizontal run of EMT (assuming they have the standoff height, otherwise unistrut and cobras).
My question however is what's the recommended practice for sealing any fasteners penetrating the flashing? I know the flashing itself is secured with screws that have a gasket backer but that won't help behind what we're securing. Silicone the hole first and then install fastener?
Also just curious if anyone has installed heavy cameras on flashing like this without sheathing supporting it from behind. We'll be putting in a large, heavy PTZ for this client and want to make sure that it is fully supported. All-thread straight through to the interior wall and secure from there?
Thanks in advance for any suggestions!