Sealant for aluminum panel roof

I have been fighting a losing battle with a screen porch roof that is made of aluminum panels butted against each other. Sealants on the seams last about a year (18 months if lucky) before leaks start again. Each time I clean the old sealants off down to bare metal with a wire brush. I have tried the normal latex, silicon, polyvinyl etc but they all fail. The roof gets full Florida sun so it is UV intensive and hot.
Any experts have a recommended product? I have not yet tried an epoxy based sealant fearing how hard it could be in the future to remove it. The panels are very tight together (no visible gaps) yet water pours through in spots in heavy rains. Is there a low-viscosity product that will get between the panels and then expand?
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On 9/28/2011 10:16 AM, JP wrote:

This is the best I've found. Still holding in one spot after five years.
http://www.sashco.com/hi/lexel.html
LdB
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JP wrote:

Have you thought about applying a strip of aluminum over the seams? I'm thinking 2-3" wide, bedded in a good caulk (urethane?) and fastened with sheet metal screws with a gasket. Like "board and batten".
Being under the batten and thus protected from UV, the bedding material should stay good. I've never tried this, just a thought. BTW, I wouldn't use epoxy.
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There are rolls of pressure sensitive tape (similar to roofing membrane) with an aluminum/mylar show surface. Available in 5", 8" widths as I recall. I used it for just what you describe.
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Just wire brushing wont remove everything that can contaminate it and ruin a bond, a strong solvent is needed like alcohol or laquer thinner, Silicones have expiration dates, Ive had silicones not get hard or not bind from using old stuff sitting on store shelves to long. I would think a good fresh silicone would work,also temperature of the roof and humidity will affect a bond.
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On 9/28/2011 11:16 AM, JP wrote:

Post some pictures somewhere with a link back here, and we can give much better advice. Kinda surprised there isn't a lap joint of some kind up there to prevent exactly this problem. Most metal roof panels I have seen, the panels overlap by 1 bump. The interlocking bumps always give the water a lower spot to run to.
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aem sends...

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wrote:

Typical Florida screen rooms use "pan roof". There are 2 common styles. The cheaper one, usually just for car ports, uses bent over edges on top of the seam and a drive flange. The better style for "rooms" uses a curved lip that locks over a lip on the preceding piece and they usually also have another pan cap over that with 3" of foam in between. That style installs with a screw and a rubber backed washer Neither requires any kind of sealant.
I am betting the OP has another problem, like perforated panels, missing washer screws or a missing drive flange if it is that style..
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how about some sort of membrane over the entire roof?
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