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I have a metal roof. Can I put rigid foam board and new metal over that?

dLwhmknvii | Posted in Energy Efficiency and Durability on

I don’t want to throw away the metal that is on the roof now, but want it to be more efficient. So I want to put rigid foam board and new metal roof over the old. Can that be done?

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  1. GBA Editor
    Martin Holladay | | #1

    It's hard to think of a good reason why you want to keep your old roofing. If the old roofing is worn out and leaking, it's time to remove it.

    However, I suppose it is possible to cover an existing metal roof with rigid foam -- but only if the metal roofing has flat seams. If the roofing is corrugated or has raised ridges, the old roofing definitely needs to come off.

  2. dankolbert | | #2

    Seems like even if it's flat, having a highly conductive material between the insulation and living space is a bad idea. Any spot sticking out at edge is going to cause problems.

  3. GBA Editor
    Martin Holladay | | #3

    Good point. The old roofing needs to come off, for sure.

  4. dLwhmknvii | | #4

    ok thanks guys for the help i guess the roof will come off i was hoping to double up and two is better then one but if it is going to cause trouble at the end then off it must be! it's so good to have you guys for help thank you, i'm a rookie at this house stuff but i'm hooked and in love with my new adventures!

  5. B9ZsdsMjT2 | | #5

    I am getting on this site late - so I apologize for my last minute comments - BUT I DISAGREE - THE ROOF DOES NOT NEED TO COME OFF. I am a roofing contractor who has spent 33 year restoring existing roof systems. Why would you want to tear off the metal and replace it? You not only are going to look at costly removal and disposal costs - but let's face it, shouldn't we give the landfills a break? I have been installing Conklin's Metal Restoration Roof Systems for the last 15 years.

    Conklin’s MR System is a complete waterproofing system for metal roofs. It stops leaks, inhibits rust, and provides an energy–efficient, long lasting, attractive finish coat that extends the life of the METAL roof for years. During the restoration process, each problem is systematically addressed, repaired and sealed before the final application of a reflective finish coat.

    ADVANTAGES of Conklin’s MR SYSTEM:

    Stops leaks with superior waterproofing
    Inhibits rust
    Increases energy efficiency and lowers utility expenses with it’s cool white, reflective surface
    Enhances the roof’s appearance with an attractive finish coat
    Extends the life of the existing roof

    Not to mention, the roof system is sustainable meaning, after the 10 year warranty, we wash the existing membrane, recoat it and add on to your warranty an additional 5 years. Two coats gives you and additional 10 years. For the cost of new metal, removal and disposal of old, why not restore it instead of replacing it. If you are interested, check out my website: and contact me - I have contacts all over the country - or I can show you how you can put it on yourself! Check out the picture gallery - the cost to restore is a fraction of what replacement costs will be.

    But this is just my opinion - good luck with your decision!

    Stan Volkman

  6. GBA Editor
    Martin Holladay | | #6

    It's perhaps understandable (although a little crass) that you want to promote your business. But you clearly misunderstood Jo's question. Jo wants to install new rigid foam on top of the roof, and your coating is not suitable for this situation.

  7. Foamer | | #7


    At the risk of being accused of promoting my industry :-), I know of one spray foam contractor who has successfully applied closed cell spray foam to the exterior of metal roofs. His system uses new purlins installed perpendicular to the trusses before the foam is applied. Once the insulation is down, a new corrugated metal roof is installed on the purlins.

    However, in your case it may make a whole lot more sense to strip the existing metal so that foam board can go on a smooth deck. My colleague's approach is used mostly on large commercial buildings. Either way, bravo to you for wanting to upgrade your insulation.

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