Quote:
Originally Posted by Neil K Walk
Weight would certainly be a factor. The roof was wood because it had to be lighter than stone, hence the buttresses. I would love to see what they would consider - but I draw the line at carbon fiber.
Sorry, I couldn't resist. I tend to fall on humor to lighten the mood. My apologies.
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Actually steel trusses would probably be lighter than oak trusses. Consider the cross sectional area required of a wood beam compared to a steel beam carrying the same weight. Steel is much stronger per pound than wood. Oak is strong, but it is also a very heavy wood
The buttresses are resisting outward thrust from the stone vaulting on the inside rather than the weight of the roof. A truss inherently has no outward thrust if designed properly so it's weight is a vertical load rather than a lateral load..
It was the interior stone vaulted ceiling that saved most of the church. It failed only where the spire fell, but it acted as a fire barrier when the burning wood trusses collapsed on it. That was the intent of the original design to have a stone vaulted ceiling since wood roofs tended to get struck by lightening, burn and fall all the way to the church floor doing much more damage.