They are going outside. It is a script font that goes on an angle. Biggest letter is around 3' x 5'. We are stud mounting them into a stucco wall.Are these going inside or outside ?? That'll make a big difference. Also, what size are these letters and how are they being mounted/installed ??
I misspoke - we are using 3/4" PVC. We are seeing all the time in sign magazines people cutting lettering out of PVC. We figured since this is going on a north facing wall, the PVC would be fine??Then, you're basically using the wrong substrate. Re-think what you want to do and how to approach such a task with something thicker and can take paint..... and the elements. Heck, even 3/4" duraply letters would be better. They'd last ya 15 years, at least.
we do alot of pvc. I prime with 2 part auto epoxy and spray with latex, never an issue. Silicone will hold just fine BUT we would drill some small studs in back for extra support. Not many maybe 4 or 5
I dunno. I think I would use acrylic or aluminum. Sounds like this job is just crying out for gold anodized aluminum letters. Maybe 20% more total cost, but less handling time and much more stable. The letters I buy have a lifetime warranty to the customer. Also much sturdier and easier to handle in the field. The main advantage, though, is killer looks!
Only 4 or 5 studs in a 15 sq ft 3/4" pvc letter ?? Unless they were all-thread, going through the wall and bolting with a flange on the other side, that doesn't seem kosher to me.