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  1. #1
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    Default White cement on a roof?

    A question for the building experts.

    My house has a Bermuda style roof that needs painting....again!

    The paint doesn't last long, maybe two years at most. Last time I painted it, I had an army of people with scrapers, removing all the old paint. A painstaking and messy job. We then painted it with a latex based roof paint, but it's already peeling, bubbling and allowing filtration again.

    So my question is borne from my recent swimming pool refurbishment. My pool is coated with Diamond bright, which is mainly just white Portland cement with coloured stone particles embedded into it. It's supposed to be hard, water and chemical resistant and last forever.

    So I thought about applying a thin layer of white portland cement on my roof rather than painting it again. Hopefully it should last longer than the paint and certainly not bubble up and peel, which is what causes the porousness.

    Any thoughts?

  2. #2
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    I would suggest that you use an elastomeric roof paint rather than acrylic.

    Sherwin Williams do a very good roof elastomeric paint and their products are available in DR.

    Preparation is key. Perfectly clean, dry, no fungus.

    White cement does not solve the problem. Cement is porous without waterproofing additives and again a clean key to the existing substrate is essential.

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  4. #3
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    Last month we put on a Lanco sealing paint, it lasts quite awhile. Not cheap, was about 7-8,000 pesos each 5 gallons [I think we needed 15 gallons for our roof, it's thick], but it works.

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  5. #4
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    Quote Originally Posted by AlterEgo View Post
    Last month we put on a Lanco sealing paint, it lasts quite awhile. Not cheap, was about 7-8,000 pesos each 5 gallons [I think we needed 15 gallons for our roof, it's thick], but it works.
    We also used Lanco once. I think it said hecho en Puerto Rico.
    It was expensive bad stuff.

    donP

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    Quote Originally Posted by AlterEgo View Post
    Last month we put on a Lanco sealing paint, it lasts quite awhile. Not cheap, was about 7-8,000 pesos each 5 gallons [I think we needed 15 gallons for our roof, it's thick], but it works.
    Lanco Elastomeric Seal Coat?

  7. #6
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    Quote Originally Posted by ju10prd View Post
    Lanco Elastomeric Seal Coat?
    That sounds right. They had two kinds, one was much cheaper, about 4500 pesos for 5 gallons.

    donP, it has worked for us for years. Our roof isn't entirely flat though, it has a small peak and pitch, might make a difference?

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  8. #7
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    Quote Originally Posted by AlterEgo View Post
    . Our roof isn't entirely flat though, it has a small peak and pitch, might make a difference?
    Yes, sitting water is one of the culprits. Even "flat" roofs are not supposed to be flat.

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    First you blast off any flaking with a pressure washer. Then you swab it down with a 20% solution of Chlorox (any brand that has the same formula and concentration) then after that is dry, you apply elastomeric paint.
    It should last for five t=years, though you might have to swab it with Chlorox and steregent to remove mildew (black stuff).

  10. #9
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    I have to repaint my house often, too often. First to go black with mildew is the roof. Next paint job I am going with go with extreme prep and I am having laborers doing it not the painters as they charge too much and do not do a good job. First off scraping then washing with trisodium phospate then finally chlor and a check to see that all chalky surfaces are clean and fresh water rinse. Next I am buying an anti mildew additative for the paint. You can buy paint that says its anti mildew but I am a skeptical person. I am convinced that the extreme mildew here comes right through the paint. I have never lived anywhere with mildew like the DR. Even my shoes get it in the closet if I am not careful. Its just a theory but I will let you know if it works. Paint jobs done right last for years and years in other places, why not here? We shall see. I did do a test on a section of the roof that went bad. I used a chlorine solution and voila, it was mildew that killed the paint. I am thinking that Dominican mildew is just tougher than normal mildew.

  11. #10
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    we use urethanizer, also from lanco. our roof is sloped. the building is 20 years old or thereabouts. zero leaks of any kind. we repaint about every two years. the house is close to the ocean so considerable exposure to salt as well as general humidity and heat.
    Lanco :: Urethanizer

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