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  1. #1
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    Default Metal roof rust repairs

    Live in a highly corrosive environment on the east coast of Florida and we are beginning to see more metal roofs. Most these metal roof coverings are galvanized and many do not have a finish coating over the galvanized treatment. As a result, many these roofs have various degrees of rust damage.
    Online I am seeing some information regarding treating and sealing rusty metal roofs. Has anyone had any experience or knowledge of a reliable process?
    Thank you for your comments.

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  2. #2
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    Default Re: Metal roof rust repairs

    Jack,

    There are three cures for that:
    - 1st cure: Proper selection of material with suitable corrosion resistance instead of basing the material selection of "cheapest price" ... more commonly known as "You DON'T get what you DON'T pay for."
    - 2nd cure: Trim the metal panels as specified and required by the manufacturer - use a shear and NOT a cut off blade as the cut off blade throws red hot sparks onto the surrounding roofing areas and the red hot sparks burn into the finish, causing what is shown there.
    - 3rd cure: When the panels are trimmed with the shear, apply the proper corrosion resistant coating to the bare metal left after trimming off the excess metal.
    - 4th cure: Part of the 1st cure - Galvalume does not stand up around the ocean's salt mist, regardless what roofers say about it.

    The repair is replacement of the affected panels.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  3. #3
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    Default Re: Metal roof rust repairs

    Based on information gathered from a couple websites, there are methods to treat this condition.


  4. #4
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    Default Re: Metal roof rust repairs

    What you show is a common problem when galvanized roofing panels are used without sealing the surface most do not think of sealing due to additional costs where the final cost would be the same as ordering out prefinished (painted) panels.

    Many think that being galvanized is the best, but in reality the pefinished (painted) metal panels are much better. I have a place on the water (sometimes in the water) in Va. Others near me used the galvanized roofing and I saw that it just didn't hold up. I put on the prefinished and have has good results. I had an extra panel left over and put it in a location that it would be in wet sand and would be covered in salt water frequently. After three or four years in need of making a repair due to storm damage, I pulled out the test panel and found it usable. Really surprised me. Offered for thought. But that does not answer your question.

    What you are showing in the picture is just the normal progress of a galv roof panel with accelerated aging due to the coastal environment. It looks like it is about 6 to 10 yrs old.

    You might look to Black Star Converter a lower cost than Eastwood Rust Converter. The latter is more expensive. Either one you should apply sealer top coats. Black Star might be your better choice. There are other products on the market in the restoration world that do the same job also. The problem is that the application of the Black Star I am familiar with has not had long enough for a longevity opinion.

    One thing about metal screw down roofs is that they are easy to replace.


  5. #5
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Jack Wingo View Post
    Based on information gathered from a couple websites, there are methods to treat this condition.
    Jack,

    There are ways to treat that condition, but the condition shown in your photo is not caused by the corrosive environment, it is caused by improper work at the time of installation, and the best way to treat that is to have the contractor replace the panels and this time do it properly - about the only way to stop the contractors from doing what they did is for them to replace the panels are their own expense ... does not take very many times of doing that and the contractors start to pay attention to what and how they install the metal roofs.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  6. #6
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Jerry Peck View Post
    Jack,

    There are ways to treat that condition, but the condition shown in your photo is not caused by the corrosive environment, it is caused by improper work at the time of installation, and the best way to treat that is to have the contractor replace the panels and this time do it properly - about the only way to stop the contractors from doing what they did is for them to replace the panels are their own expense ... does not take very many times of doing that and the contractors start to pay attention to what and how they install the metal roofs.

    Jerry,
    Explain how the panels damaged "... it is caused by improper work at the time of installation,...". What is your interpenetration/description of the improper work/installation method used causing the resulting situation?

    What I see is pitting oxidation/rust on the flat sections of the panels along with the screw heads. Am I missing something in the picture?


  7. #7
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Garry Sorrells View Post
    What I see is pitting oxidation/rust on the flat sections of the panels along with the screw heads. Am I missing something in the picture?
    "Am I missing something in the picture?"

    Yes.

    You are missing (well, I am sure you can see them ) all those pits caused by what I already described in my previous post (which I am sure you also read):
    Trim the metal panels as specified and required by the manufacturer - use a shear and NOT a cut off blade as the cut off blade throws red hot sparks onto the surrounding roofing areas and the red hot sparks burn into the finish, causing what is shown there.
    I can probably count on one hand the number of times I've seen sheet metal roofing contractors trim the panels with shears instead of with those abrasive cutoff blades ... all those red hot sparks flying away from the saw blade are red hot pieces of metal being abraded away, and they embed themselves into and through the finish which was applied by the factory to the panels (sure, some el cheapo panels are not finished, but as has already been stated, you don't get what you don't pay for, in this case you don't get a finish coating if you don't pay for it).

    Also, in this case, you don't get what you do pay for as the contractor presumably was paid to do the work properly, trimming the panels with a shear, then opted to use the 'cheap and quick' method of using a cutoff saw. What you see in the photo is exactly what you get when that happens.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  8. #8
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    Default Re: Metal roof rust repairs

    Jack,
    Was the pitting uniform across the roof panels top to bottom?
    Or was the pitting within the bottom 3 ft of the panels?
    What the the roof size? (length and width)


  9. #9
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Garry Sorrells View Post
    Jack,
    Was the pitting uniform across the roof panels top to bottom?
    Or was the pitting within the bottom 3 ft of the panels?
    What the the roof size? (length and width)

    Garry,
    I assume you asked about the bottom 3 foot thinking this might be where the cuts could be. If you have to cut a roof panel the cut would be at the top. Generally you map a building out, give a cut list to the supplier and they will pre-cut your package.( I've received them 28' long). Localized damage from spark spray should be found around openings, inside and outside corners and possibly near the ridge cap......I use double cuts and nibblers.

    Last edited by Mark Hagenlock; 02-11-2013 at 01:40 PM. Reason: misspelling

  10. #10
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    Default Re: Metal roof rust repairs

    Mark,
    You never know how they were installed. Bottom 3 ft question has a reason, waiting for Jack to respond.

    Shears/nibblers best way, yes. Seems that the cutting action redistributes the Galvanizing on to the cut edge causing it to self heal, or so I have heard. Not to sure if that is actually what happens or not. Works for me though.


  11. #11
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    Default Re: Metal roof rust repairs

    Surprising no one has fussed about the screws on top of the ridge/rib....instead of on the flat .....


  12. #12

    Default Re: Metal roof rust repairs

    Jack,

    Oftentimes pitting similar in appearance to that shown in the photo is a sign of of severe corrosion of the underside of the panels, and the small specs of red rust are actually the first spots to rust all the way through the panel. When this condition exists you can usually hear a slight crunching sound when the panel is stepped on.

    Also, the panels are fastened improperly. Two things: (1) although some panel types call for 'stitch' screws on top of the primary ribs, to hold the side laps tightly together, I don't believe this is one of those, and (2) the screws are normally placed as shown here on page 5: http://www.fabral.com/assets/media/d...-postframe.pdf

    Don Putnam
    Home - Putnam Construction Consulting


  13. #13

    Default Re: Metal roof rust repairs

    Jack,

    To answer your question, if the rust is minor it can be treated using cold galvanizing compound: RustOleum.com

    Proper preparation of the panels is essential.

    Don Putnam
    Home - Putnam Construction Consulting


  14. #14
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    Default Re: Metal roof rust repairs

    The panels are 15' to 20' in length and rust spots are located in various roof panels location, I doubt they are from shavings.

    What at the conquences of fasteners located on ribs rather than flat area of roof panels.


  15. #15
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Garry Sorrells View Post
    Surprising no one has fussed about the screws on top of the ridge/rib....instead of on the flat .....
    Some installation instructions specify the fasteners through the ribs, some through the pan area, some on each side of the rib, some on one side of the rib, some through the overlapping ribs to secure the laps together.

    My observation above is simply to show that *one MUST NOT assume* that all metal panels are to be fastened through pan area, and that in fact *many* metal panel roofs specify the panels be fastened through the ribs - and that there are many which specify *both* types of fastening for the same panels.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  16. #16
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Jack Wingo View Post
    What at the conquences of fasteners located on ribs rather than flat area of roof panels.
    Depends.

    The consequences may be that is how the roof was approved at the inspection - because that was the required fastening method.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  17. #17

    Default Re: Metal roof rust repairs

    Jack,

    If I were the inspector of this roof I would report the observed corrosion and that the fastening pattern does not appear to comply with any of the industry accepted patterns, and leave it at that. From a liability standpoint you would probably not be held responsible for identifying the panel type or the specific fastening pattern approved for this panel, but the pattern used in this case is observable and it obviously complies with none of the standard patterns. Since the pattern is observable you could conceivably be held responsible for reporting on it.

    In my experience stitch screws are appropriate to hold side laps together on some panel systems, but I'm not aware of any screw-down panel system of the type shown in your photo where screws are driven through ribs to attach the panels to the roof deck. Stitch screws are very short and do not reach the deck. A good illustration of this can be found on pages 23-24 here: http://www.metalsales.us.com/files/i...st%20Coast.pdf

    As you will see in nearly all fastening patterns, the attachment screws are driven next to primary ribs and, on some wider panels, occasionally with one screw at the center of the wide flat of the panel. Two of the screws in your photo are driven through the intermediate stiffening ribs. This is never correct. Also, the middle screw is torqued hard enough to cause indentation of the panel and chew up the rubber washer; that's another defect. When you see that, it's an indicator that some of the screws may have 'stripped' the deck and are likely to back out. Screw-down panel systems are notorious for leaking at screws that have backed out. Once the rubber washer is no longer under compression the screw hole will leak.

    I hope this is helpful. Keep in mind, I'm a roof consultant, not a lawyer, so I'm definitely not qualified to offer any of this as legal advice.

    Don Putnam
    Home - Putnam Construction Consulting


  18. #18
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Don Putnam View Post
    and that the fastening pattern does not appear to comply with any of the industry accepted patterns,
    Why would you say that?

    What is "industry accepted patterns" if not what is included in the installation instructions and product approval?

    I admit that you must inspect a lot more metal panel roofs than I do as I only do about 3-5 per week, and I only have the installation instructions and product approvals to go by, not something called "industry accepted patterns", whatever those are - would you kindly guide me to your knowledge source for that?

    you would probably not be held responsible for identifying the panel type or the specific fastening pattern approved for this panel, but the pattern used in this case is observable and it obviously complies with none of the standard patterns.
    Again, please, a source which I can use because I clearly have no idea how metal roofs are to be installed, and being as I only inspect 3-5 per week I suppose I will never know ...

    In my experience stitch screws are appropriate to hold side laps together on some panel systems, but I'm not aware of any screw-down panel system of the type shown in your photo where screws are driven through ribs to attach the panels to the roof deck. Stitch screws are very short and do not reach the deck. A good illustration of this can be found on pages 23-24 here: http://www.metalsales.us.com/files/i...st%20Coast.pdf

    As you will see in nearly all fastening patterns, the attachment screws are driven next to primary ribs and, on some wider panels, occasionally with one screw at the center of the wide flat of the panel. Two of the screws in your photo are driven through the intermediate stiffening ribs. This is never correct. Also, the middle screw is torqued hard enough to cause indentation of the panel and chew up the rubber washer; that's another defect. When you see that, it's an indicator that some of the screws may have 'stripped' the deck and are likely to back out. Screw-down panel systems are notorious for leaking at screws that have backed out. Once the rubber washer is no longer under compression the screw hole will leak.

    I hope this is helpful. Keep in mind, I'm a roof consultant, not a lawyer, so I'm definitely not qualified to offer any of this as legal advice.

    Don Putnam
    Home - Putnam Construction Consulting
    For a "roof consultant" you are certainly spreading MISINFORMATION about what is "normal" ... maybe you need to start inspecting MORE METAL PANEL systems from different manufacturers so you can widen your knowledge base on what is acceptable and what is not.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  19. #19
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    Default Re: Metal roof rust repairs

    A little from the practical side of the world about the thought process that installers will use out in the field. All manufacture installation instructions aside. Many installers work from a monkey see monkey do or they are taught one way using nails and carry the same process forward to all installation applications. Not right not good just fact.

    From the installer point of view the nail into the rib is better when using nails.. The nail will work loose over time alowing the compression on the washer to decrease. With the nail on the rib ridge there will be a lessor chance of leaking since it will not be sitting in water. If the nail was in the flat there would a greater chance of leaking as the nail backs out over time loosing the washer's seal.

    Why use screws rather than nails? Screws hold better and are less likely to back out over time. So as the the thinking goes using screws instead of nail is better. So so it the same way as you would using nails.

    So, many using that same thought process will use the screws on the rib thinking that they are reducing the chance for leaking as was with the nail keeping it out of the water. But in practice, there is a a heightened probability of over tightening the screw causing the panel to flex. Also, it is a wast of the additional cost into the screws when you can get better value out of their use.

    Screws also have a difference of holding power with the flexing of the panel especially under high wind conditions. Screws on the flat will hold the panel far better than on the rib as the panel tries to flex and move from wind. Screws will maintain the compression of the washer far better and more consistently when on the flat.

    I always like bedding all screws using a dab of sealant without regard to their location. Kinda like a belt with suspenders.


  20. #20

    Default Re: Metal roof rust repairs

    Hello Jerry,

    Thank you for your comments and opinions regarding my last post.

    When I referred to "industry accepted patterns" I was referring to fastening patterns as published by the manufacturers and suppliers of thru-fastened, or 'screw-down' panel systems, which I believe is the same or similar to what you referred to as "installation instructions". In each of my posts I included links to panel suppliers to illustrate the most commonly accepted/recommended pattern, which is placement of the screws in the wide flat of the panels, directly adjacent to the primary ribs. I can't tell for sure from Jack's photo which panel system we're looking at, but it looks pretty close to the Tuff-Rib panel shown here: http://www.bestbuymetals.com/pdf/tuf...tion-guide.pdf , which, on page 5, again shows the screws placed adjacent to the primary ribs. In my experience this is the most widely accepted placement pattern. Are you aware of an installation guide that shows the pattern in Jack's photo to be acceptable, with the screws driven through the intermediate stiffening ribs and the primary ribs of this type of panel profile?

    Garry Sorrells' most recent post makes several good points, particularly regarding the diminished wind resistance due to greater panel flexibility when screws are placed through the panel ribs. An additional point to consider when placing fasteners in primary ribs is the reduction of panel stiffness (which is provided for the most part by the structural integrity of the primary ribs) when point loading of the top flange of the rib occurs at each point of fixity in a wind uplift event. The primary ribs are more likely to buckle at each screw than if the screws are located beside the rib. When the ribs buckle the panel becomes flimsy and is more likely to be blown off. The same theory is evident when walking on structural roof panels. Installers learn very quickly to step over primary ribs and walk only on the wide flats of the panels. R-Panels spanning 5' purlins do just fine with a man's weight at mid-span, but step on a rib and it and the panel will usually buckle.

    Anyway, I'm off to widen my knowledge base on what is acceptable and what is not.

    Don Putnam
    Home - Putnam Construction Consulting


  21. #21
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Jerry Peck View Post
    Why would you say that?

    What is "industry accepted patterns" if not what is included in the installation instructions and product approval?

    ......I only have the installation instructions and product approvals to go by, ......


    .

    Jerry, You say you have installation instructions. Great. Please share. Which ones are you using as reference? Manufactures? Web links? PDFs?


  22. #22
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    Default Re: Metal roof rust repairs

    Not to let a dead horse lie.

    Jerry, do you have installation instructions for all screw in the top of ribs instead of on the flat ?


  23. #23
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    Default Re: Metal roof rust repairs

    Quote Originally Posted by Garry Sorrells View Post
    Jerry, You say you have installation instructions. Great. Please share. Which ones are you using as reference? Manufactures? Web links? PDFs?
    Quote Originally Posted by Garry Sorrells View Post
    Not to let a dead horse lie.

    Jerry, do you have installation instructions for all screw in the top of ribs instead of on the flat ?
    I said I have installation instructions and product approval when I inspect the roofs - I stand there with the installation instructions and product approval in my hands doing the code inspection, once I leave, the installation instructions and product approval then go back in the plastic zip lock bag with the permit, either signed as approved or disapproved, depending on whether or not the fastening matches the installation instructions and product approval.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  24. #24
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    Default Re: Metal roof rust repairs

    Jerry,
    I am confident that you can not produce any installations instructions that support the OPs picture. Maybe your memory is fuzzy. It is common across the industry not to put screws into the ribs as is shown in the OP. Common in the industry becomes a general industry standard when most if not all adhere to similar screwing location area and patterns. Word play aside. Screws in ribs of a ribbed panel is not accepted as correct except for specific situations. It is possible that the roof was inspected and the person doing the inspection allowed the incorrect screwing pattern. Which made it acceptable for the permit (by that inspector) but not actually correct for the installation.

    Here are some examples of installation instructions. With the exception of corrugated panels they are basically the same as in not on the ribs. So for those who would like to compare:


    Fabral
    http://www.fabral.com/assets/media/d...-postframe.pdf

    ABC
    Fastener Location

    American Building Components: Common Trim Details

    ASC
    Country Rustic Corrugated Installation Guide

    http://www.ascbp.com/files/BR128_LtGaugeInstall.pdf (Note difference in 2 ˝” corrugated roof installation.)

    MBCI
    FL11918_R0_II_StormProof Details.pdf

    http://www.mbci.com/pdf/design_tech_...LineManual.pdf

    Exposed Fastening Roof Panels
    PBR Panel
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image001.gif[/IMG]
    PBU Panel
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image002.gif[/IMG]
    PBD Panel
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image003.gif[/IMG]
    PBC Panel
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image004.gif[/IMG]
    5-V Crimp
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image005.gif[/IMG]
    7.2 Panel
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image006.gif[/IMG]
    Retro-R® Panel
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image007.gif[/IMG]
    Rain Guard®
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image008.gif[/IMG]
    Perma-Clad®
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image009.gif[/IMG]
    Stormproof®
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image010.gif[/IMG]
    WeatherSafe®
    [IMG]file:///C:/DOCUME%7E1/Garry/LOCALS%7E1/Temp/msohtml1/01/clip_image011.gif[/IMG]


    McElroy Metal
    http://www.mcelroymetal.com/elements...06Rev02-11.pdf

    http://www.mcelroymetal.com/elements...M496-01-13.pdf


    Metal Depots
    http://metaldepots.com/pdfs/PBU_typicaldetails.pdf



    Metal Sales
    http://www.metalsales.us.com/files/i...stallGuide.pdf

    IC72-Panel Roof

    http://www.metalsales.us.com/files/c...CTR%202012.pdf

    http://www.metalsales.us.com/files/c...CTR%202012.pdf

    http://www.metalsales.us.com/files/c...CTR%202012.pdf

    Union Corrugating Co

    http://www.unioncorrugating.com/docu...tionManual.pdf

    http://www.unioncorrugating.com/docu...nual_11-07.pdf

    http://www.unioncorrugating.com/docu...stallation.pdf


    http://www.unioncorrugating.com/docu...stallation.pdf (corrugated)

    Gulf Coast Supply
    http://www.gulfcoastsupply.com/insta...Rib_Manual.pdf

    http://www.gulfcoastsupply.com/insta...5-v_Manual.pdf

    Classic Metals Inc
    http://www.classicmetalinc.com/sc/images/pbrpanel.pdf


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