We are building a green roof on the show house. Green roofs are heavy so we are paying a lot of attention to the weight on the roof. We were going to lay the green roof materials directly on top of the tar roof that was there. It was in good shape.
But the we did a test to see it’s thicknesss and it turns out there is over 50 years of layer upon layer of tar. And this stuff is HEAVY. So we had to remove it.
And when it was all cleaned off there were beautiful wide planks. Now we can lay the green roof material over them and the roof will be ten times lighter.