PVC or Plywood?

[Ken]

Hi. I have a client wanting a sign for the rooftop of his building. It's a peaked roof, clad with sheet metal ( the stuff with the ribs with protruding screwheads). This is a one-sided sign facing the Trans-Canada Highway.
He wants to run the sign down the full length of the building ( 54 feet)
He's thinking 2 feet tall. He will provide the framework and assembly of the framework - he's a welder. I just have to make the sign face. The sign will read:

Builder's Hardware - Rentals - Rebar

After doing some preliminary layouts ..it should fit Ok. I'm trying to talk him into a 48 foot sign instead ot 54..and he seems OK with that.( 6 pieces, 2 x 8 feet, to make the length)
I originally suggested SignPly ( 1/2 inch plywood with white aluminum face.) but I am now reconsidering this in favour of Intecel ( 1/2 inch PVC sheeting.
My reasoning is that the PVC should be superior to the plywood in longevity. Is about the same price but I then do not have to paint the rear of the plywood or seal the edges or provide edge-cap.
My concern is about expansion/contraction and also about joining the PVC panels together.
Should there be some kind of backer at each seam? I was thinking a 6 x 24 inch piece of the same PVC material screwed into the back of each seam. Panels butt-joined?
How would you mount this into a frame? I understand that the fasteners should be able to allow for expansion..But how much?
Let's say we use 1/4 inch bolts thru the sign face into the frame. I'm thinking a 3/8 hole throught eh PVC will be sufficient to allow for exp/cont. and a 1/4 inch "play" on the sign frame.
Does this sound reasonable?
Instead of a full perimeter frame wrapped around the edge of the sheet(s), is there another way?
TIA.
Ken

[Billct2]

Dibond or Alumalite would be my choice. The seams should line up with the frame construction, so no backer required. S/S Bit tip screws to install. You can do a .040 aluminum frame if you want, but it probably won't be noticeable from any distance.

[Ken]

Thanks Bill. I actually dont want the framework to be seen at all, so I am wondering about a method where we can just screw (bolt) the sign face to the frame. Stainless fasteners will be used. I dont want rust and the client does not want maintenance. I'll use 9 year vinyl on this.
6mm Econolite would also fit the bill here.
I would prefer to not have the fastener heads showing on the sign face. My thought there is to cover each screwhead with a small cirle of vinyl to match, wether red or white)
Any thoughts on the expansion/contraction issue?
TIA.
Ken

[johnnysigns]

i'd think alumalite. be sure to provide a gasket between the signface if you use aluminum and his framework is steel.

[Pro Signs & Graphix]

Ken,

Considering that he is an actual welder, he should be easy to sell the idea of heavy gauge aluminum. The aluminum would give him the greatest longevity and better mounting options. May we also suggest to scrap the idea of vinyl, unless there are some some sort of gradients etc, and instead make a mask for paint.

In the beginning, it will seem that these option would cost more but in actuality the result will be the greatest longevity and the lowest maintenance.

[imaSIGNr]

Many will disagree, but I would use MDO on this one. Making sure that the edges are WELL sealed with epoxy over bondo. Then you can use a " Reisner" screw to sink in flush with the face of the sign and then place a 1" round vinyl circle same color as background over the screw head so there is no screw heads showing....An idea. I do this method often.
I wouldn't put anything on the seam to cover it. It will not be noticed.

[Pro Signs & Graphix]

I would use MDO on this one

I guess that you can now be included in what seems to be one of four, on this forum (myself included), that actually like MDO. Unfortunately, too many people give MDO a bad rap to argue about its usefulness and effectiveness - thus the suggestion of aluminum (on my part).

[Checkers]

The people who bad-mouth MDO are the same ones buying the imported crap from China or elsewhere. I still prefer to use it, but I would probably pass in this situation. I would take Pro's advice and go with aluminum.
But, I would have the client make the entire structure, including the background and powder coat it. Then, depending on the design, I would use Gemini Letters, which would be guaranteed for life :)

Checkers