I see in France most of the multistory buildings, there is a black stone crush placed on the top of the buildings. I would like to know whether they use it for certain climate or reason.

(Crushed stones, placed without cement, as a raw stones) Please share if you have an idea.


AFAIK the main purpose of stones and pebbles on roofs is:

  1. to keep the roofing material in place
  2. to protect the roofing material from UV radiation and thus prolonging its lifespan (for that the roof must be completely covered with stones and pebbles)
  3. to prevent snow from sliding off a sloped roof (but for this larger stones are often used)
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  • now i got it :) – Yadav Chetan Jun 1 '13 at 9:49
  • 2
    In addition to what you said, it's also there to prevent the black tarpaper layer underneath from getting too hot. That's a longevity factor, but it also helps keep the building from absorbing too much heat, which increases cooling bills during warmer months. Although this isn't why they do it, anything that increases the albedo of a black roof is going to have a very beneficial effect with respect to climate change, which is fundamentally a sustainability issue. – Nate Jun 7 '13 at 8:33

The main advantage of crushed stone is that,Crushed stone grains have different shapes depending on their flakiness. Their surface is coarse, therefore they have good cohesion with cement-and-sand mix in the concrete production process. there for it uses in roofs.

Cohesion property:The force of attraction that holds molecules 
of a given substance together. It is strongest in solids, less strong in liquids, 
and least strong in gases. 

Thus crush stone binds with cement and sand and provide high strength to roofs and buildings which provide strength to buildings.

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  • Yes you are right but i means crush placed on the roof without cement, as a raw small stones. – DataMiner May 31 '13 at 19:06
  • @user986789 can you explain more? – Yadav Chetan Jun 1 '13 at 4:41

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