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In the United States, most buildings are built with a double loaded corridor. This means that they have a central hallway, with units on both sides. Because of egress laws, buildings above four stories (3 stories above grade) are also required to have two separate means of egress for all occupants. This leads to wasteful hallways, inefficient floorplates (80-85%) [1].
In Europe and most of the world outside of the US and Canada, most buildings have a singular staircase. A single means of egress allows for more efficient floorplates, less embodied carbon, less construction cost, more compact buildings, cross-ventilation, and more feasible small-lot development [1]. Buildings with a single means of egress and constructed with units around a staircase allow for social benefits as well - having less neighbors allows for the stair to function like a short "street" would.
Single Stair Floorplans
Single Stair Floorplans
The floorplans in our building will look like this. Each floor will have a few units, between 3 or 4, which is the code maximum. Our building also has a ~95% efficiency ratio. The units will have cross ventilation, as well as be designed for family use. Read about floorplan design on our floorplan page. The units are all oriented around a staircase. Units are very shallow, allowing light to permeate through all ends of the units. This design would not be possible with a traditional double-egress approach.
Cost savings
Cost savings
Given that a second staircase eats up about 400 square feet per floor, over four stories a second staircase can waste around 1,600 square feet across the entire building. At our construction costs, a second staircase would cost us a significant amount because of the necessity of adding a hallway.
Environmental benefits
Environmental benefits
Because of the savings of not having to construct a corridor, we will save a lot in terms of material used to construct the building with our 95% efficiency ratio. Additionally, single stair construction will allow use to make a lot more units with windows on more than one side, so they can utilize cross ventilation, saving energy and utility costs in the summer when bringing in exterior air can cool hot interiors
Social benefits
Social benefits
In a single staircase structure with four units per floor and six stories, that is 24 units total. Humans can know 40 people [2], so these buildings are really at a scale that you can feasibly know all of your neighbors.
Sources
City of Vancouver report on Point Access Blocks - https://www.larchlab.com/city-of-vancouver-report-on-point-access-blocks/
How allowing single-staircase buildings could change Virginia’s housing market - https://www.virginiamercury.com/2022/05/05/how-allowing-single-staircase-buildings-could-change-virginias-housing-market/
Second Egress by Conrad Speckert - https://secondegress.ca
The Single-Staircase Radicals Have a Good Point - https://slate.com/business/2021/12/staircases-floor-plan-twitter-housing-apartments.html
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