Painting of corrugated metal roof





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  1. #1
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    Default Painting of corrugated metal roof

    Hi Guys,

    My workshop has a corrugated metal roof (sink dak). Flat, 5x5m. It's showing it's age these days. With heavy rain, it sometimes leaks a bit at some of the overlaps of the panels. I want to sort it out, seal the overlaps, and paint the thing.

    I've never painted "sink" before. If there anything specific I should be looking at? What precautions should I take? What preparations should I do for this?

    Any pointers?


    Chris
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  3. #2
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    Thumbs up Re: Painting of corrugated metal roof

    Perhaps it is a Zinc roof. Easy job DIY talk to your local paint supplier.

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    Default Re: Painting of corrugated metal roof

    Raw galvanised metal needs an etch primer. There are plenty of sealing options, from sealant gum to impregnated overlay fabric. In my opinion, talk to a Duram agent, they'll have a decent product for you. A metal roof with a proper pitch and overlap shouldn't leak though.
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    Thumbs down Re: Painting of corrugated metal roof

    Quote Originally Posted by mike cullen View Post
    Perhaps it is a Zinc roof. Easy job DIY talk to your local paint supplier.
    Last edited by Robbief; 2020/04/22 at 02:17 PM.
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  8. #5
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    Default Re: Painting of corrugated metal roof

    Quote Originally Posted by mike cullen View Post
    Perhaps it is a Zinc roof. Easy job DIY talk to your local paint supplier.


    Yes, a Zinc roof, is a "sink dak" in Afrikaans.


    Chris
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    Default Re: Painting of corrugated metal roof

    Are your overlaps proper? If not, it might leak a bit there.
    I have an old (circa 1972/73) corregated roof on my house. I sprayed it with ordinary red oxide about 7/8 years ago and it seemed to work. Although the Plascon Roofpaint I put over it, powdered up and disappeared over the years.
    Paint shop suggested that the water base paint was attacked by the solvent based red oxide. I will repaint at some point with bitumen aluminium solvent based paint.
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  11. #7
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    Default Re: Painting of corrugated metal roof

    I once painted a new corrugated roof. It was a 12x3m area.

    I used Galv-etch to etch and clean it and painted with Megabond Thermshield without a primer.

    We sold the house 12 years later. No peeling at all.

    I have seen a few roofs with peeling paint due to improper under coats.
    https://www.galv-etch.co.za/
    Last edited by Sawdust; 2020/04/22 at 03:42 PM.
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  13. #8
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    Default Re: Painting of corrugated metal roof

    Have a look at the new paint on rubber solutions. I used it on a problematic ,nearly flat, section that even docters could not sort. And one rainy season down the line it is so far so good. Did not even need primer.

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    Default Re: Painting of corrugated metal roof

    Do not use acrylic pain sealer (pap en lap) it will corrode the zink/galv. I use Sikalastic, a rubber sealant that can be painted on with the membrane. Also a good idea to seal/ prime metal sheets with bitumen product from ABE before you put any pain/ sealant on

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    Default Re: Painting of corrugated metal roof

    First of all , good hose down with a pressure cleaner , edge primer and plascon roof coating , should last for years . As far as the leaking , roof anchors mostly the problem , the rubber washer fails due to the elements over the years , replace . You might find that the wood under the nails can be rotten in which case you should replace with oversize anchors Also look for movement on the roof ( inadequate roof trusses ) it will loosen up the roof anchors and no matter how you seal this it will leak
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  19. #11
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    Default Re: Painting of corrugated metal roof

    Sorry to say. You will NEVER stop leaks on your flat corrugated roof.
    Corrugated sheets should not be used on slopes lower than 15 degrees.
    If it was my roof I will replace the sheets with Kliplok type and never have concerns again. A bit more expensive than painting etc, but (even financial) worthwhile.
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    Default Re: Painting of corrugated metal roof

    Use poprivits and snap them together. But on the ridges.

    Plenty poprivits.
    Last edited by Henris; 2020/04/23 at 06:42 AM.
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    Default Re: Painting of corrugated metal roof

    Quote Originally Posted by JohanMaree View Post
    Sorry to say. You will NEVER stop leaks on your flat corrugated roof.
    Corrugated sheets should not be used on slopes lower than 15 degrees.
    If it was my roof I will replace the sheets with Kliplok type and never have concerns again. A bit more expensive than painting etc, but (even financial) worthwhile.
    My experience with Corrugated sheets on flattish roofs is that in hevay rain, the ridges fill up with water and then spill over causing a leaking. No matter the overlap. In other words the slope is not enough for water to flow down fast enough. What Johan is saying here. Or also when raining with heavy winds, the wind will drive the water under the sheets. A bigger ridge like IBR does not cause that
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  25. #14
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    Default Re: Painting of corrugated metal roof

    Nothing wrong with corrugated , done a lot of garages , houses etc . No pop rivets please , problem with small slopes is the wind driving the water up the slope and then it leaks against the flashing if there’s a wall . I had my corrugated bend ( no joints or overlapping on the lengths ) Clip-lock is a good idea but not good in storms , most of the roofs that was lost in the “hurricane “ that hit Krugersdorp a couple of years back was clip-lock
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    Default Re: Painting of corrugated metal roof

    Quote Originally Posted by Hyades View Post
    Hi Guys,

    My workshop has a corrugated metal roof (sink dak). Flat, 5x5m. It's showing it's age these days. With heavy rain, it sometimes leaks a bit at some of the overlaps of the panels. I want to sort it out, seal the overlaps, and paint the thing.

    I've never painted "sink" before. If there anything specific I should be looking at? What precautions should I take? What preparations should I do for this?

    Any pointers?
    1st rule. Clean off all the rust. Loose, flaking. surface
    2nd rule after cleaning the rust. Paint anti rust/ etch primer/ P4 zinc primer over where the rust used to be.
    Pre drill a pilot hole before nailing down/ fastening any loose sheeting.

    Unless you can place a torch on membrane such as Derbigum over the overlaps and joints, do not waste your money buying the 5 litre tins of waterproofing liquid that come with a "free" membrane.
    Rather buy a roll of "Flashband". ABE is one of the maunfacturers, but the prices vary between the brands. All do an excellent job, and are exactly the same.
    Use a 75mm wide flashband. Don't use smaller, as movement will cause the edges to peel.

    Do not use enamel paint on an iron/ tin roof.
    Do not use roof paint, unless it is designed for iron/ tin/ zinc.

    Etch primers such as NS4, Hammerite, come in a huge variety of colours.

    And remember that your "flat" roof has served it's purpose for many years.
    Don't replace it. Fix it.
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  28. #16
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    Default Re: Painting of corrugated metal roof

    Something that wasn't discussed in detail is the galvanizing part. I was lead to believe that if a corrugated roof is old and rusty its not necessary to use galvanising primer. Only on newish/shiny zink. Any remarks or facts about that please.
    Last edited by Spiceman; 2020/04/23 at 10:31 AM.
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    Default Re: Painting of corrugated metal roof

    Quote Originally Posted by Francois Theron View Post
    My experience with Corrugated sheets on flattish roofs is that in hevay rain, the ridges fill up with water and then spill over causing a leaking. No matter the overlap. In other words the slope is not enough for water to flow down fast enough. What Johan is saying here. Or also when raining with heavy winds, the wind will drive the water under the sheets. A bigger ridge like IBR does not cause that
    Thanks for your support Francois. Exactly as you explain. Although, even IBR is dicey as its lowest designed slope should not be less than 7.5degrees.

    Where Kliplok was blown off in storms they were not installed correctly. Never blame the product if the artisan is suspect too.I have a roof that has a 100mm drop over 6m under Kliplok and it has never showed any leak, even with 50mm hail spread over it (at one time).

    The guys who install corrugated on flatter roofs are doing it as a cost saving only. There can be NO other sensible reasoning. And it is ugly to say the least.
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  30. #18
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    Default Re: Painting of corrugated metal roof

    Carports usually use IBR sheeting, and there is minimum fall if not any.

    Clay roof tiles recommend a minimum fall of not less than 17 degrees.

    If galvanized sheeting has weathered. (6 months exposed to sun & rain) You do not need to wash the sheeting with a galvanized cleaner before painting.

    The use of galvanized primer - which is always yellow, for some unknown reason, acts as a bond between the metal and the final coat of paint.
    Personally I have painted galvanized barriers with galv primer and then enamel paint, and the paint has peeled within a year.

    And I have painted corrugated roof sheeting on a trio of gemini huts, with only etch primer and green roof paint, and 3 years down the line they are looking good. With no leaks where I have patched using Flashband.
    I met some crazy people.... They made me their leader.

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  31. #19
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    Default Re: Painting of corrugated metal roof

    Quote Originally Posted by emileheyns View Post
    Do not use acrylic pain sealer (pap en lap) it will corrode the zink/galv. I use Sikalastic, a rubber sealant that can be painted on with the membrane. Also a good idea to seal/ prime metal sheets with bitumen product from ABE before you put any pain/ sealant on
    Reviving here ...

    I'm considering using Sikalastic, i've watched some videos on the product and it seems very sufficient. Has anyone else used it? See photo below, I used a contractor from Pretoria, which was my first mistake in this process to build a new roof and braai.

    He sealed it with some sort of fiberglass and rubber application around the chimney. (because "he doesnt use pap & lap yadda yadda)

    We had 3 drops of rain, literally 5min ± 3 weeks ago, it leaked. He came back to re-seal it, only to see that he used pap & lap upon my return. Now last night we had 6 drops, leaked again. Safe to say he's not coming back, I just don't have the energy. Will Sika do the job? Should i try and rip off his pap & lap application first?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by Morne - Skip; 2020/09/21 at 09:07 AM.

  32. #20
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    Default Re: Painting of corrugated metal roof

    I see Hyades / Chris gives his location as the airport on St. Helena Island. Will be interesting which of the suggested options are actually available at his presumed location.
    Mike Nieuwoudt
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