4 ms·

(Am I missing a joke?) He's talking about 5-over-1 or one-plus-five buildings. They're 6 story midrise buildings that have 5 stories made of wood on-top of on

(Am I missing a joke?) He's talking about 5-over-1 or one-plus-five buildings. They're 6 story midrise buildings that have 5 stories made of wood on-top of one made of concrete. They're extremely common in North America, and they aren't firetraps because they have sprinkler systems, redundant emergency staircases, building wide fire alarms.

bombcar 4y ago
They ARE firetraps when being built of course. But once finished they’re pretty normal. A concrete building doesn’t protect you from fire as much as people might think.
ars 4y ago
Why is the bottom one made of concrete? (i.e. and not just the foundation)
- coryrc 4y ago
  Residential requires a higher level of fire safety than commercial and additional separation between uses for occupant comfort (f.ex. sound). Additionally, there is usually parking and that also requires a lot of separation.
  - tremon 4y ago
    So it's not just different building materials, it's also mixed-use zoning? 1 level of commercial space + N levels of living space above it?
coryrc 4y ago
No, see https://en.wikipedia.org/wiki/5-over-1 https://en.wikipedia.org/wiki/5-over-1 "5" and "1" are not the number of floors, they are the construction type, 5 being (primarily) built of dimensional lumber and drywall, 1 being reinforced concrete. The type for heavy timber is "4". This, a building with CLT would never be 5-over-1. It might be 4-over-1, but I bet it's sufficiently inherently fire-resistant that most designs will be solely type 4.
- MichaelCollins 4y ago
  > No, see https://en.wikipedia.org/wiki/5-over-1 https://en.wikipedia.org/wiki/5-over-1 No, see https://en.wikipedia.org/wiki/5-over-1 https://en.wikipedia.org/wiki/5-over-1 > The name derives from the maximum permissible five floors of combustible construction (Type III or Type V) over a fire-resistive Type I podium of one floor for "5-over-1" or two floors for "5-over-2", as defined in the United States-based International Building Code (IBC) Section 510.2. > Some sources instead attribute the name to the wood framing of the upper construction; the International Building Code uses "Type V" to refer to non-fireproof structures, including those framed with dimensional lumber.[5][6] First sentence affirms my comment, second sentence affirms yours. I suspect the second usage is primarily European, or just mistaken. In America, 5-over-1 refers to the number of floors. Particularly, the upper five might be Type III not Type V, but it's still called a 5-over-1. And if there are two bottom Type I floors, it's called a 5-over-2.

bombcar 4y ago

They ARE firetraps when being built of course. But once finished they’re pretty normal. A concrete building doesn’t protect you from fire as much as people might think.

ars 4y ago

Why is the bottom one made of concrete? (i.e. and not just the foundation)

coryrc 4y ago
Residential requires a higher level of fire safety than commercial and additional separation between uses for occupant comfort (f.ex. sound). Additionally, there is usually parking and that also requires a lot of separation.
- tremon 4y ago
  So it's not just different building materials, it's also mixed-use zoning? 1 level of commercial space + N levels of living space above it?

coryrc 4y ago

No, see https://en.wikipedia.org/wiki/5-over-1 https://en.wikipedia.org/wiki/5-over-1 "5" and "1" are not the number of floors, they are the construction type, 5 being (primarily) built of dimensional lumber and drywall, 1 being reinforced concrete. The type for heavy timber is "4". This, a building with CLT would never be 5-over-1. It might be 4-over-1, but I bet it's sufficiently inherently fire-resistant that most designs will be solely type 4.

MichaelCollins 4y ago
> No, see https://en.wikipedia.org/wiki/5-over-1 https://en.wikipedia.org/wiki/5-over-1 No, see https://en.wikipedia.org/wiki/5-over-1 https://en.wikipedia.org/wiki/5-over-1 > The name derives from the maximum permissible five floors of combustible construction (Type III or Type V) over a fire-resistive Type I podium of one floor for "5-over-1" or two floors for "5-over-2", as defined in the United States-based International Building Code (IBC) Section 510.2. > Some sources instead attribute the name to the wood framing of the upper construction; the International Building Code uses "Type V" to refer to non-fireproof structures, including those framed with dimensional lumber.[5][6] First sentence affirms my comment, second sentence affirms yours. I suspect the second usage is primarily European, or just mistaken. In America, 5-over-1 refers to the number of floors. Particularly, the upper five might be Type III not Type V, but it's still called a 5-over-1. And if there are two bottom Type I floors, it's called a 5-over-2.