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The thesis isn't particularly clear but what I think they want is a modification to Canadian building code so that structures up to a certain size don't need a

The thesis isn't particularly clear but what I think they want is a modification to Canadian building code so that structures up to a certain size don't need a second egress. They want that, I think, because that aspect of code makes it hard to design housing that sits in the middle of the scale between single family homes and high rises. That middle tier of housing seems like it could be important if you consider what NIMBY-ism and a shortage of housing is doing to some cities. I couldn't find out out _why_ a second fire exit makes it hard though. Maybe it's not the door, but the need for an extra stairwell? I'd hesitate to call it pretentious wank just because I don't understand it, so let's just say that the site was clearly not written for a lay audience.

henrikschroder 4y ago
You have to go digging on that site a little bit to get to the why: "The building typology of five to six-storey apartment buildings usually involves a single shared central stair, accessed directly from the street with typically two to four dwelling units per floor. However, because the Ontario Building Code requires two means of egress, mid-rise buildings in Toronto are designed with two exit stairs connected by a common corridor. The result is that mid-rise construction only proves feasible on larger sites where around ten or more units can fit within a typical floor plan to achieve an efficient floor area ratio. Zeidler explains that “this appears to be a reasonable precaution for life safety. However, the life safety of this single stair type in Europe has been equal to, if not better than ours,” due to the fact that the single stair scheme is shared between fewer units. By changing the code requirement for two exit stairs, apartment buildings of midrise height could be designed around a single common stair. For instance, a point-access block, the dominant housing typology in dense urban contexts like Berlin, Paris, or Barcelona, is currently not permitted in Canada." https://secondegress.ca/A-Wicked-Problem https://secondegress.ca/A-Wicked-Problem
mjmahone17 4y ago
A big chunk of why is the % of floor area that is used for housing versus “support”. Basically a single stair layout gives you 90-95% floor efficiency, and a double stair is closer to 80-85%. People don’t rent common spaces like stairs, so you can bring the value of a building up by ~10% by allowing each apartment to have only a single exit staircase. Also if a lot is small (like 20ft wide or less), you have to compromise the design. For instance, instead of having full-floor units that get cross ventilation (windows at front and back), you may need to have duplex units that take up 40% of the front or back (so only get one side of the building).
RegnisGnaw 4y ago
Its the second stairwell.
monknomo 4y ago
Requiring two egresses usually means that the building will not have an apartment that spans the width of the building, instead there will be a central hallway to connect every apartment to two stairwells. That central hallway seems small, but it eats a fairly substantial percentage of the footprint space of the building. (elevators and trashrooms are also examples of things that eat a lot of footprint; limiting them for smaller buildings is beneficial for floorplan efficiency) And since people do not like bedrooms without windows, having apartments that don't span the width of a building limits possible floorplans, and drives the apartment design towards studios and 1 bedrooms. The buildings tend to become very wide in order to accommodate enough apartments to make them worthwhile to build, so they tend to use up a high percentage of the lot they are sited on, which reduces greenspace and other resident amennities.
- nradov 4y ago
  In most areas, the building code explicitly requires a window in every bedroom. This serves as an additional emergency exit, either directly on the ground floor or with assistance from firefighters on higher storeys.
  - bbojan 4y ago
    Ironically, in Toronto, not every bedroom is required to have a window [1]. [1] BCC Ruling No. 14-03-1366: https://web.archive.org/web/20210422142050/http://www.mah.gov.on.ca/Page11347.aspx https://web.archive.org/web/20210422142050/http://www.mah.go...
    - jaclaz 4y ago
      And this shows how internationally building codes can be very different. In Italy a room, any room for residential use, not only needs a window, but the window(s) surface must be at least 1/8 or in some cases 1/12 of the floor surface of that room, a windowless room can only be a bathroom (with a compulsory exhaust fan) or a closet/corridor/storage/utility room. But this comes not from fire related laws, but rather from minimal health requirements (natural light, ventilation).

henrikschroder 4y ago

You have to go digging on that site a little bit to get to the why: "The building typology of five to six-storey apartment buildings usually involves a single shared central stair, accessed directly from the street with typically two to four dwelling units per floor. However, because the Ontario Building Code requires two means of egress, mid-rise buildings in Toronto are designed with two exit stairs connected by a common corridor. The result is that mid-rise construction only proves feasible on larger sites where around ten or more units can fit within a typical floor plan to achieve an efficient floor area ratio. Zeidler explains that “this appears to be a reasonable precaution for life safety. However, the life safety of this single stair type in Europe has been equal to, if not better than ours,” due to the fact that the single stair scheme is shared between fewer units. By changing the code requirement for two exit stairs, apartment buildings of midrise height could be designed around a single common stair. For instance, a point-access block, the dominant housing typology in dense urban contexts like Berlin, Paris, or Barcelona, is currently not permitted in Canada." https://secondegress.ca/A-Wicked-Problem https://secondegress.ca/A-Wicked-Problem

mjmahone17 4y ago

A big chunk of why is the % of floor area that is used for housing versus “support”. Basically a single stair layout gives you 90-95% floor efficiency, and a double stair is closer to 80-85%. People don’t rent common spaces like stairs, so you can bring the value of a building up by ~10% by allowing each apartment to have only a single exit staircase. Also if a lot is small (like 20ft wide or less), you have to compromise the design. For instance, instead of having full-floor units that get cross ventilation (windows at front and back), you may need to have duplex units that take up 40% of the front or back (so only get one side of the building).

RegnisGnaw 4y ago

Its the second stairwell.

monknomo 4y ago

Requiring two egresses usually means that the building will not have an apartment that spans the width of the building, instead there will be a central hallway to connect every apartment to two stairwells. That central hallway seems small, but it eats a fairly substantial percentage of the footprint space of the building. (elevators and trashrooms are also examples of things that eat a lot of footprint; limiting them for smaller buildings is beneficial for floorplan efficiency) And since people do not like bedrooms without windows, having apartments that don't span the width of a building limits possible floorplans, and drives the apartment design towards studios and 1 bedrooms. The buildings tend to become very wide in order to accommodate enough apartments to make them worthwhile to build, so they tend to use up a high percentage of the lot they are sited on, which reduces greenspace and other resident amennities.

nradov 4y ago
In most areas, the building code explicitly requires a window in every bedroom. This serves as an additional emergency exit, either directly on the ground floor or with assistance from firefighters on higher storeys.
- bbojan 4y ago
  Ironically, in Toronto, not every bedroom is required to have a window [1]. [1] BCC Ruling No. 14-03-1366: https://web.archive.org/web/20210422142050/http://www.mah.gov.on.ca/Page11347.aspx https://web.archive.org/web/20210422142050/http://www.mah.go...
  - jaclaz 4y ago
    And this shows how internationally building codes can be very different. In Italy a room, any room for residential use, not only needs a window, but the window(s) surface must be at least 1/8 or in some cases 1/12 of the floor surface of that room, a windowless room can only be a bathroom (with a compulsory exhaust fan) or a closet/corridor/storage/utility room. But this comes not from fire related laws, but rather from minimal health requirements (natural light, ventilation).