Letters on metal siding...no access behind

[phototec]

Everyone has their own method obviously, but I use studs (with nuts for plumbing the letters on the low spots in the siding), VHB tape, and silicone.

It's also a good idea to either drill the holes slightly over-sized or wallow them out a little with your drill bit. The threaded studs can hang up on the metal and make it impossible to push the stud all the way in without pounding on the letter - at which point you risk damaging the letter, dimpling the face if the stud is close to it, etc. This is especially true of the siding has any flex to it, which it often does. If using 10-24 studs and installing in metal, I use a 7/32" bit.

Moze, Good point on the over size drill bit, I will have to try that next time!

 

[Moze]

Years ago, I ruined a foam letter because the stud hung up in the hole in metal siding just like the OP is describing. I couldn't get it to go in further and I couldn't get it out (there were three other studs that were basically all of the way in).

It's one of those things you only have to do once to learn your lesson.