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  1. #1
    Join Date
    Dec 2008
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    Erwin, TN
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    187

    Default Tar and Gravel Roof

    Never seen a tar and gravel roof on a residential roof, what's the life expectancy and what should I be looking for ?

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  2. #2
    Join Date
    Mar 2012
    Location
    Lansdale, PA
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    876

    Default Re: Tar and Gravel Roof

    Quote Originally Posted by Sam Morris View Post
    Never seen a tar and gravel roof on a residential roof, what's the life expectancy and what should I be looking for ?
    Old Coal tar and gravel roofs could sometimes last 30-40 years. That pitch is too steep for a typical coal tar roof so I assume it is built-up asphalt. It really depends upon the number of plies, etc. Could last as little as 10 and possibly up to 30 years, but 20 max would be more realistic. Where I see them they are usually on flat roofs with parapets so I look for deterioration at the parapets, etc. to get an idea what condition it is in. I would not quite an average service life for a roof like that, and if you do not have an idea of the age I would say the service life cannot be predicted. Other that looking at visible flashing details it is hard to judge condition.


  3. #3
    Join Date
    Mar 2007
    Location
    Connecticut
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    1,828

    Default Re: Tar and Gravel Roof

    that roof should be gauged by the age of the home, which is?


  4. #4
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: Tar and Gravel Roof

    Quote Originally Posted by Sam Morris View Post
    what's the life expectancy and what should I be looking for ?
    About 10 years *before* that green mossy stuff begins to grow on it.

    In South Florida where that used to be a common roof, life expectancy was quite long as the gravel ballast (the gravel is there to help hold the roof covering down - and to protect the underlying roof materials from the sun and weather) - 25-40 years was not uncommon when not on a nearly flat roof (roof slope allows for relatively quick drainage of water off the roof). On flat roofs the life expectancy was somewhat less.

    That is for the old built-up roofs with gravel ballast as those old roofs were laid with more care - newer built-up roofs were pretty much like all newer stuff - knock it out as quickly and cheaply as possible, which means using thinner (lighter weight) felts, less asphalt, and fewer layers (plies, 5-ply was common, now you seldom see anything more than 3-ply ... when you see a roof like that - which is seldom as that takes a 'tar kettle' and those can be quite dangerous to use, especially if the temperature is allowed to get too high and the kettle bursts into flames. I've seen that happen, and the person(s) near the kettle are covered with hot asphalt of about 450 degrees, and that burns the skin right off, and the heat stays there as long as the hot asphalt does - ever try getting hot asphalt off your shoes? It is a bad scene and the people are seriously burned, sometimes they don't make it. Even when the kettle is not allowed to get too hot and explode, the hot asphalt is dangerous to handle and you do not want any spilled on you.

    Roofers who use those tar kettles pay *A LOT* for workmen's compensation insurance, even more than other roofers pay because working a roof can lead to falls, and the fall is not from a standing position to the ground, the fall is from the roof to the ground.

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

  5. #5
    Join Date
    Mar 2007
    Location
    Orlando, FL
    Posts
    1,340

    Default Re: Tar and Gravel Roof

    You should look for bald spots (no gravel or rock); alligatoring asphalt; crazed asphalt; "humped" sections that indicate previous repairs (which would be either a flood coat of hot asphalt or a 5 gallon bucket of Bull, depending on who did the work); ponding and other low spots; soft sheathing when walked upon; weird or non-standard flashings (many people don't know how to work on these roofs). If it looks wrong, it probably is...


  6. #6
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,248

    Default Re: Tar and Gravel Roof

    Quote Originally Posted by Dom D'Agostino View Post
    If it looks wrong, it probably is...
    I second that!

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

  7. #7
    Join Date
    Dec 2008
    Location
    Erwin, TN
    Posts
    187

    Default Re: Tar and Gravel Roof

    Quote Originally Posted by Jerry Peck View Post
    I second that!
    Thanks for all the info, very helpful


  8. #8
    Join Date
    Feb 2009
    Location
    Southern Vancouver Island
    Posts
    4,546

    Default Re: Tar and Gravel Roof

    T&G can be rejuvenated by removing the gravel, applying a fresh layer or two, and laying down new gravel. The only sure way to know the thickness is by destructive testing.

    I have T&G on one half of the house, and it makes a fine roof, that is safe to walk on. My roof is over 40 and well cared for. I would to cap it with a waterproof deck and solar panels. But that will have to be for the next owners.

    The moss grows on organic debris. Rake it off.

    John Kogel, RHI, BC HI Lic #47455
    www.allsafehome.ca

  9. #9
    Join Date
    Feb 2008
    Location
    Caledon, Ontario
    Posts
    5,005

    Default Re: Tar and Gravel Roof

    Time for replacement. The moss is feeding on the materials and is usually a sign of failure.


  10. #10
    Join Date
    Aug 2011
    Location
    california
    Posts
    56

    Default Re: Tar and Gravel Roof

    Ref. Raymond Wand:

    The T&G materials are inorganic, hence, there is nothing for the moss to "feed on".

    The organic debris particles that bed the moss, & the covering moss itself, will retain moisture and can cause expansion especially in freezing conditions.

    Expansion will create minute cracking and will often displace the gravel.

    Moss on any surface should be removed.

    AAMOI: I know of a built in 1948, San Leandro Ca. duplex that has the original T&G roof.
    The T&G is in great shape.


  11. #11
    Join Date
    May 2012
    Location
    Bay Area
    Posts
    15

    Default Re: Tar and Gravel Roof

    We have a fair amount of tar and gravel roofs out here in the Bay Area. If I saw something like that in your pictures, I would say it's probably due for replacement! Recommend a qualified roofing contractor...


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