Low pitch: salt water = ?

Guest User
1/19/2014
I'm on a brackish (semi-salty) canal, with nearby pine and mangrove trees. My existing tiles (painted with elastomeric white paint) would turn completely black in about 5 years if left unchecked (which I think is some kind of mold). My hope in selecting metal is to cut down on maintenance and the need for annual pressure cleaning. Also, being in Florida I have the issues of hurricane force winds and torrential rain. I've met with 3 contractors (the "find a contractor" resource on this site only has 2 results, one of whom quoted mine). One was so concerned with the pitch that he didn't even want to quote metal or tile! One of the other 2 contractors showed me from 2.0-2.3, and said metal would meet Miami-Dade code, but obviously pitch could be an issue. 1. Given the geography, waether and low pitch, should I be focusing on one metal system over another? 2. Will the metal roof deliver on my hopes of lower-maintenance? 3. If I need to continue pressure cleaning, could this damage the kynar paint? 4. This forum has mentioned that even dark colors can have reflective pigment. Looking at the Englert color chart, I don't see any special reference to "high R" other than the SRI numbers - does Englert use the pigments described in this forum (I'm most interested in a medium bronze color)? 5. I was quoted for .032 and .040 thicknesses - what's the practical difference? I'd use the price difference to invest in a secondary water resistance barrier, but want to understand the trade-offs. This forum is an amazing resource. Thanks in advance for your input into what I hope is my last roof replacement!
Todd Miller
Isaiah Industries, Inc.
1/19/2014
Thanks for your post, and thanks for thinking metal. Most metal roofs are approved for use down to 3:12 pitch. Many standing seams and some through-fastened products can be used down to 2:12. For lower pitch roofs I would suggest a mechanically seamed standing seam. It sounds like you're looking at aluminum which is a good choice for the salt climate. I'd say that in your case there is not a huge difference between .032 and .040. The heavier would normally be used for a more structural application which is not what you have. Most of the products that have reflective pigment will be listed on the Energy Star list. The requirement for that is 25% reflectivity which can be achieved with many of the reflective dark colors. A reflective light color may reach 65% or greater reflectivity of radiant heat. These are the SRI numbers you mentioned, Mildew and mold and algae will not attack the Kynar finishes as much as tile. However, anything in a damp climate with a lot of airborne fungus can develop a buildup of mildew over time. Proper curing of the paint is important so I would stick to a name brand product and domestic metal. You can light pressure wash if desired. I hope that this helps. Please feel free to write back. Again, thank you.
Guest User
1/20/2014
Thanks so much for that response! I forgot to mention in the first post that I am indeed focused on aluminum as you made clear. At my house, things rust quickly! Thank you for putting me at ease on .032. Does thickness have an impact on "oil-canning"? I will need to periodically go up on the roof the blow leaves, but if I wear crocs or soft-soled shoes it sounds like a .032 can take it. The Englert color chart has each color along with an "R" reflectivity number, an "E" emissivity number, and an "SRi" number, but the "energy star" label just appears at the bottom of the page - does that mean that ALL colors have the pigment and 25% reflectivity? The bronze for example is "R32.3 E91 SRI35.6" - maybe one of those numbers indicates the 25% reflectivity. On this forum I was surprised to find a study by the Florida solar energy center that showed attic temperatures actually higher with metal standing seam than with white tile: http://www.classicmetalroofingsystems.com/info/FSEC-Summary.pdf#sthash.72Sc7hh5.dpuf. Since I am looking at a darker color, could I actually see my energy bills go UP (since my quotes indicate application directly on the roof deck, and not with any baffle or gap)? On your recommendation for mechanically fastened standing seam, I think that was what I was quoted on: "englert series 2000, .040 18" wide standing seam metal roof system mechanically fastened to the substrate", but than another says "032 riffe versalock 1.5 metal roof panels" - is that not necessarily "mechanically fastened"? It was explained to me that even with Englert materials, there are 2 ways to construct the roof: one with snap-lock (?) and one where (I think) the panels are pre assembled elsewhere? Both were said to cost the same, but the snap lock was explained to be better if one panel should ever need replacement. I'm not sure if these 2 types are discussed here somewhere, and if one of those is better for my low-pitch/hurricane zone circumstances. Finally, having established that my low pitch makes me "border-line", would you say a secondary "peel and stick membrane"/"self-adhered HT sheet" is highly recommended? I'm told Miami-Dade is one of the only places on earth where the code requires this be installed on TOP of the 30lb/versashield, and not underneath it (ie: directly on the roof deck), so I'm not sure I get the full benefit of having this extra layer (the purpose of which should be to protect the house if the metal is blown off).
Todd Miller
Isaiah Industries, Inc.
1/20/2014
Heavier metal will be less likely to oilcan but .032" generally runs a good panel provided the machine is properly adjusted and the surface upon which it is being installed is not forcing ripples into the panels due to unevenness. I believe that the SRI number is the number that Energy Star looks like and it must be at least 25 to meet their standards. You'd really need to ask Englert direct for details on their approvals but the list of all Energy Star approved roofing materials is available on the Energy Star website and you can search by manufacturer. The Classic testing done at FSEC covered several years and generally metal out performed the white tile. At that point, though, the reflectivity is coming from the color. Tile tends to hold heat and continue to radiate it into the atticspace even after the sun has gone down. That's not a good thing. Some of the testing done did show the value of an airspace though. For example, a formed metal shingle did better than white standing seam, because of the integral airspace in the metal shingle. Mechanically seamed means that roof panels are put on the roof and then a crimping device or machine is run down the seams to seal them tight. Again, I really can't interpret the nomenclature of other manufacturers. you would need to contact them direct. Snap lock is NOT the same as mechanically seamed. What is your roof pitch? Extra membrane helps but I still never suggest installing any product at a lower pitch than which it is intended. It will be a problem at some point.
Guest User
1/20/2014
Again, excellent answers. My pitch ranges from 2.3 on the main section, to as low as 2.0 on a smaller section. Low pitch! I hadn't considered that the pitch could also affect the selection of the secondary membrane too! I guess I would have to ask who the manufacturer is (not disclosed on quote), and research whether it is suitable in my circumstances.
Guest User
1/20/2014
Re-reading my quote I see that it is for "Englert series 2000 snap-lock metal standing seam", so given your advice I will have to ask that company to get me a mechanically seamed quote (they did say they did that system also, and given my pitch I'm a little concerned that I was only quoted for snap-lock).
Dick Bus
1/20/2014
At the pitch you have .032 aluminum is acceptable. You can expect to see oil canning from the right angle, but at your pitch I would not be concerned about it. Some homeowners think that oil canning is part of the aesthetic appeal of a vertical seam metal roof. You do not need felt paper when installing High Temp peal and stick. Clip spacing and trim/flashing details are the most critical items to be concerned about in regards to high wind zone areas. At your pitch you should only consider a mechanically seamed panel. Contact any of the Metal Roofing Alliance manufacturer regarding the appropriate panel, clip spacing and flashing details.
Guest User
1/20/2014
Your response, together with Todd's, make it clear that mechanically seamed is the way to go, and I now question the judgement of the company that quoted a snap lock system. In researching the local NOAs (notices of acceptance under building code), I also see that the other quote's product also has better pressure readings (-118/159.25psf vs. -62/144.5psf for the snap-lock), so they win on those numbers AND the system type (mechanical, not snap). Clip spacing is dictated by the county, and all the NOAs have the same stats: 16" field and 8" perimeter/corner. So no clear winner there. Not sure if the local code allows me to omit the 30-lb felt, because all quotes have it, and it is specifically mentioned in the NOA: "minimum ASTM D 226 Type II". Perhaps "minimum" implies I could substitute the peel and stick? But I don't seem to get any price break: it costs an extra $1/sf (on both quotes). As a compromise, I was told today the peal and stick can be used just on the valleys and other sensitive areas, which should bring that cost under $1000 from $4000. I guess no discount on my hurricane insurance though.
Eric Novotny
An informed customer is the Best Customer!
1/20/2014
I always prefer the synthetics when it comes to underlayments but they do add up when you are talking about the high temp peel and stick. I would seal the eaves with it as well as the valleys and rakes. That, with the underlayment, should give you all the protection you need.

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