In this charette we will be looking at a vacant lot in the City of Philadelphia. When referencing the code we will be citing from the Philadelphia Code, Title 14, Zoning and Planning.
When beginning a project, we research the existing property by deed search and zoning search. The deed search will describe the legal property dimensions and give us our metes and bounds. The zoning search will give us allowed uses and dimensional standards.
For this parcel, the lot size is 15' x 63' with a 3' wide alley. It is a corner property bounded by two streets. The zoning designation for this parcel is CMX-2.
We begin by declaring the maximum footprint allowed in this zoning district. On a corner property we are allowed to occupy 80% of the lot, leaving 20% open air / rear yard. There is a rear yard requirement of 9'-0" but the open-air requirement overrides by being a larger ratio. So, we lay out the footprint 80/20 as shown.
Now we are able to extrude our volume and implement other dimensional standards. The height of any structure in this zoning district is limited to 38' to the top of the roof surface. There is no limitation on number of stories and some designers are able to fit four floors in 38', but we will stick with three stories for this exercise.
Now we have our volumes sketched out.
We have a three-story structure that is 38' tall and occupies 80% of the lot.
We are allowed to have a roof deck in this zoning district and with that allowance comes with some limitations. A roof deck must be set back from the front property line 5'. The roof deck must have a guardrail all around that is 42" tall. To access the roof deck, they allow for a "roof access structure" that can be 125 sq. ft. max. in footprint and 10' tall. It needs to also be setback from the front property line 10' min.
Let's add a fence around our rear yard at 4' as mandated by the zoning code for corner lots.
We are able to have "projected bay windows", this aspect of the code is outlined and governed by the Streets Department as they exist over the public right of way. Bay windows are limited based on size, frontage, height above grade and proximity to property lines. In this example we are allowed to add a second-floor bay window in the rear that spans 15' and projects 3'.
CMX-2 is a mixed use zoning designation and this designation allows for limited commercial uses and multi family residential with some caveats.
This designation requires that the ground floor have a commercial use and this commercial use must exist in the full frontage width of the property and extend at least 30' in depth.
After that we are allowed to have a residential use and the number of dwelling units is dictated by the lot area. This parcel is 945 sq. ft. and with that we are allowed 1.968 units which is rounded down to 1 unit. Your lot area is divided by and arbitrary figure and that figure is 480 sq. ft.
So, we will have a commercial storefront tenant on the ground floor and basement, then one dwelling unit that is accessed from the rear of the first floor and occupies the second and third floor with a roof deck and access to the rear yard.
Once our zoning requirements are sorted out we are free to continue the design of the building keeping in mind all we have learned thus far. Floor plans below.
A wireframe view of the scheme.
The floor plans.