Why does the floor have to be so much more massive than the walls?
Just scouring through everything I can find about building a floor on top of a wood floor and paying close attention to the warnings regarding structural damage. If the floor can hold the walls and ceiling, then wouldn't it also be able to hold an additional mass like a floating floor (assuming it's the same mass as the walls)?
A little confused about floor mass
Originally posted at johnlsayers.com, topic 13716.
Simple really, when you put your mind to it. The floor is basically the foundation for whatever is the structure. So whatever is the structure also dictates how much the floor/footing is able to support...total building material weight, total environment(weather, snow, hurricanes, earthquakes, etc.), et. al. A concrete foundation can support more weight overall. That is what concrete is good at, compression. A wooden foundation is not going to have the same ability. You can build and install typical framing directly on top of a wooden structure. The problem is that wood isn't as good as concrete under compression. So if you overload a wooden foundation structure the weight you use will be far less then what a concrete type foundation will be able to support and sustain just by virtue of the properties of the concrete. Added steel reinforcement in concrete increases the ability of the concrete to span farther reaches, doesn't really change the compression ability of the concrete...because that is what it is already good at.Why does the floor have to be so much more massive than the walls? Just scouring through everything I can find about building a floor on top of a wood floor and paying close attention to the warnings regarding structural damage. If the floor can hold the walls and ceiling, then wouldn't it also be able to hold an additional mass like a floating floor (assuming it's the same mass as the walls)?
Sure, I understand that. A stronger floor is needed to support more mass. But from an isolation standpoint.. why does the floor need to be more massive than the walls or ceiling? Am I missing something here?
From a physics standpoint, is there actually more pressure on the original wood floor if you have a floating floor on top of it? Lets say, hypothetically I took my floating floor and put it on top of the structure and the structure was just resting on the original floor - would that be less pressure on the original floor?
"why does the floor need to be more massive than the walls or ceiling? Am I missing something here?"
Yes, you are missing something. I explained most of the first part.
"From a physics standpoint, is there actually more pressure on the original wood floor if you have a floating floor on top of it?"
No there is not any more pressure.
The issue is that the wooden structure cannot support the vertical weight and will collapse, if not from a typical roll-over of the joists doing a domino, then from the actual smashing of the wood from too much weight.