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Opinions wanted: Situation: Client wants "roof signs" that are parallel with the roof of his buildings gutter edge. It's a long building..about70ft. He wants them raised above the metal roof about 8" so snow can slide and melt underneath the signs. He wants the signs aprox 16" high x 96"long and will want them down the entire length of the building. I'll build some sort of angled bracket that these will mount to and then mount the bracket to the metal roof.
Question 1)Would you recommend Dibond (thin aluminum faces with PVC core 1/8" or 1/4") OR Alumilite (thin aluminum faces with corrugated plastic core with flutes running the 96" length)at 1/4" [OR something else]
Question 2)Would you put 1 bracket at each end, or 3 total with one in the middle. Snow load/weight is the question. Would the middle one hold more snow and increase the weight load pushing on the sign and make it worse?
-------------------- Phil Steffen, 29 Van Rensselaer St City of Saratoga Springs DPW Saratoga Springs NY 12866 Posts: 563 | From: beautiful Saratoga Springs NY | Registered: Aug 2001
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Any moisture that gets into the corrugation will expand when frozen causing material failure. Center supports are needed. I'd consider horizontal 2x4's mounted top and bottom behind the panels. Also, a strip or rubber between the brackets and roof to prevent electrolysis.
-------------------- The SignShop Mendocino, California
Making the simple complicated is commonplace; making the complicated simple, awesomely simple, that's creativity. — Charles Mingus Posts: 6712 | From: Mendocino, CA. USA | Registered: Nov 1998
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I have used both. The Alumilite is nice stuff to work with, but you do have to reinforce it against wind a bit more. I do not know the difference in wind shear strenght, but someboy here will probably have that or look at Architectural Standards. Both seem to hold up very well in the elements. I would run at least verticle supports every 24" to make it as strong as possible with pending snow pushing up against the bottom inside, even with 8" of gap from the roof. I would also run a top and bottom parallel horizontal. The quality will be appreciated long after the price will be swallowed.
Now the brackets...Steel and attaching them to the roof might be an issue. They should be triangular and maybe 1-1.5 inch angle iron, galvanized. I would get a steel shop to make them up to be sure they are all the same. Bolting them to the roof will be a big challenge to not allow any water leakes through the roof. Tough challenge. The whole thing would be alot easier if you placed the sign beneath the roof edge in front, unless they are just deadset againt the idea. I hate interferring with roof water leakage problems.
I hung a 30'x4' 3d sign on a Chevy store, 15 years ago. I built 2x4 CDC aupports to mount dibond on. It was strong and very secure against the south wind. Then about five years ago, they demolished the building and rebuilt a new showroom. Before they demolished the building, I had the chance to really look at how well it had lasted. The structure was still 100%, but I could see some of the silicone sealer/chalk at the bottom of the frame bases was beginning to allow some water in. Gotta be very careful with the roof seal. Unfortunately, the bulldozer ate the entire sign, before I could get permission to remove it for use somewhere else. Too bad, because it was a $13,000 sign that was trashed. Two months later they ordered another similar one for the new building! There is no accounting for public stupidity.
-------------------- Preston McCall 112 Rim Road Santa Fe, New Mexico 87501 text: 5056607370 Posts: 1552 | From: Santa Fe, New Mexico | Registered: Nov 1998
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You can use edge cap along the top edge of the alumalite to prevent water from getting in (I leave it off the bottom to allow moisture to drain out). However, you have a potential water penetration problem every place where you have a screw/fastener to hold the brackets to the panels. For that reason I think Dibond is the better choice for a snowy/icy locale.
I've been using epoxy to attach aluminum to aluminum. (I don't usually use steel framing, so I haven't tried that... not sure what the difference in expansion is.) LocTite H8100 "Speedbonder" has been my go-to product for aluminum composite panels for two years. It sets up to working strength in about 15 minutes (you gotta work fast!) and develops full strength in a few hours. I now glue-and-clamp panels to aluminum angle (or aluminum square tube) in the field. By the time one panel is attached to the wall the next panel is set up and ready to go. No screws on the face of the panels.
The only drawback to the expoxy is that you'll have to cut everything apart with a sawzall when its time to take down the sign. That expoxy is permanent.
-------------------- :: Scooter Marriner :: :: Coyote Signs :: :: Oakland, CA :: :: still a beginner :: :: Posts: 1356 | From: Oakland (and San Francisco) | Registered: Mar 2001
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All the signs are individually put up. Leaning toward the Dibond I guess. Don't know how much stronger the 1/4" is over the 1/8".
Does anyone know if it gets brittle like plain PVC does in the winter cold?
-------------------- Phil Steffen, 29 Van Rensselaer St City of Saratoga Springs DPW Saratoga Springs NY 12866 Posts: 563 | From: beautiful Saratoga Springs NY | Registered: Aug 2001
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If you use the Dibond brand material you should be fine with the 3mm (1/8") as long as you've got some bracing running behind it all. The aluminum protects the plastic core. I use aluminum channel for bracing because that way I know the coefficient of expansion is the same for the Dibond and for the bracing. The brackets that attach the bracing to the building can be whatever (steel, wood, aluminum).
here's some background:
My understanding is that Dibond (and other Aluminum Composite Panels, aka ACPs) was developed to be used in curtain wall applications for storefronts and skyscrapers. (It goes in the window frame systems wherever the glass isn't). The actual Dibond stuff has thicker aluminum skins than some of the other economy brands. Dibond used to offer a 50 year warranty (since it was designed to be an exterior building skin, it had to last). It might still be 50 years.
The cheap competitors have less aluminum and usually offer 3-10 year warranties.
-------------------- :: Scooter Marriner :: :: Coyote Signs :: :: Oakland, CA :: :: still a beginner :: :: Posts: 1356 | From: Oakland (and San Francisco) | Registered: Mar 2001
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Thanks guys! Neil- the length wasn't really an issue, but thanks for the heads up. Scooter: Good idea on the aluminum bracket coefficient dilithium crystal info. And I wonder if the warranty change is due to the aluminum, or the changes to the core material.
Again- anyone on the brittleness of Dibond like materials in bitter cold due to the "PVC" core?
Thanks all around.Phil
-------------------- Phil Steffen, 29 Van Rensselaer St City of Saratoga Springs DPW Saratoga Springs NY 12866 Posts: 563 | From: beautiful Saratoga Springs NY | Registered: Aug 2001
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We just did a job like this. Dibond on a 1"x1" aluminum tube frame. 1.5x1.5 Galvanized Slotted Angle For the triangular Brackets. Just be sure you're securing to a stud.
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The core of dibond is NOT PVC, it's polyethylene. I have never seen an instance of the core of this material cracking. Also, properly installed, the 1/8" would do fine. You are over-thinking it.
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We use aluminum composite panels all the time here and we have temperatures that drop sub -40C often. We also have some wicked winds on the open prairie where these signs are installed and I have never experienced any issues with cracking. We brace the signs with horizontal stringers every 24" so you should be fine with the fastening at the top and bottom.
-------------------- “Did you ever stop to think, and forget to start again?” -Winnie the Pooh & A.A. Milne
Kelly Thorson Kel-T-Grafix 801 Main St. Holdfast, SK S0G 2H0 ktg@sasktel.net Posts: 5496 | From: Penzance, Saskatchewan | Registered: May 2002
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