Why do people cover their flat roof with gravel?

I have an extention with a flat roof, which is bare (not covered with gravel or anything of that nature). I noticed that my neighbours flat roofs, however, are covered with gravel. Is there a benefit derived from doing this, especially considering the fact their roofs are covered in algae as a result of the gravel (I presume as my has no algae)? Thanks

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  • 1 decade ago
    Favourite answer

    the gravel is mostly put on flat felt roofs to serve as a heat barrier from the sun, otherwise the felt would soften and blister and then when it was cold the creases in it would crack and cause leaking,

    put too much on and the weight of the gravel will crack the felt as well and cause an increase in weight on the flat roof and possibly buckle inwards

    Source(s): worked alongside a roofer for years
  • hogge
    Lv 4
    4 years ago

    Flat Roof Gravel

  • 1 decade ago

    I agree with "Steve C" I do have worked with a contractor that does "hot and "shingle" Roofing and the gravel has it's purpose there.

    "Steve C":

    the gravel is mostly put on flat felt roofs to serve as a heat barrier from the sun, otherwise the felt would soften and blister and then when it was cold the creases in it would crack and cause leaking,

    put too much on and the weight of the gravel will crack the felt as well and cause an increase in weight on the flat roof and possibly buckle inwards

  • 5 years ago

    Gravel Roof Advantages

    Most gravel roofs are inexpensive to build, offer some protection to vulnerable asphalt against UV damage, and the stones are very durable.

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  • 1 decade ago

    The gravel heats up with the sun absorbs water and drys the roof. It also acts as a weight on the felt to stop the wind catching it.

  • Boe
    Lv 7
    1 decade ago

    Its extends the life of the roof where its not directly exposed to the elements. And second the rocks block the suns UV rays which is what breaks down the roofing material over the course of several years.

  • Anonymous
    1 decade ago

    The gravel that is placed on the top reduces the rays that the sun is shining down

    in your house. Reducing the heat that is produced during the summer that you do not

    want because of high gas bills and things such as that.

    Thanks

  • Anonymous
    1 decade ago

    In hot weather it protects the roof felting from cracking and when it rains it breaks the rain up so it is not heard inside, and prevents puddles of water on the roof.

  • 1 decade ago

    Its not algae, its moss. They do it to improve heat retention in the house and it also acts as a minor type of sound proofing, especially after the moss has grown.

    YOu tend to see that more in ecologically friendly builds.

  • 1 decade ago

    To protect it from UV rays, which I believe will cause quicker deterioration.

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