Mixed-use site plans

What a mixed-use site plan has to fit

A mixed-use site plan stacks two or more programs on one parcel and makes them share it: housing or offices above, shops, restaurants or services at grade, a parking supply that serves both, a service and loading side, open space, and a fire apparatus lane along the tall face. Most of the decisions the plan records are set by four published rule sets, and each one is a number a reviewer can check.

The ground floor comes first. SeaTac, Washington requires at least 50% of the street-facing ground floor length, excluding vehicle entrances, to be designed for retail, commercial or service use ^[1]. That sets how much of the frontage the residential lobby, the garage entrance and the service door can take. In Texas the rule runs the other way for the cities SB 840 covers (see the state table below), and a project counts as "mixed-use residential" when at least 65% of its square footage is residential ^[7].

The preliminary site plan carries these in its site data table: gross floor area by use and by floor, the ground-floor frontage share and depth, units by type, parking required for each use against the shared-parking requirement, the loading and service area, open space, and the aerial fire lane drawn to scale. Engineering stays with the client's engineer of record.

Ground floor: frontage, depth, height and transparency

The depth rule shapes the building section as much as the plan. The residential lobby, the elevator core and the parking entrance are planned around a commercial band that averages 30 ft deep along the street, and 15 ft is the shallowest point the rule allows ^{[1, 2]}. Seattle publishes its numbers in a summary it marks as illustrative only, so the Land Use Code itself is read for a live site ^[2]. For storefront planning on the retail side, see retail center site plans.

Shared parking: the four published tables

Every shared parking table below uses the same arithmetic: multiply each use's required spaces by the percentage for each time period, sum each column, and take the highest column as the requirement ^{[4, 5]}. The Urban Land Institute's Shared Parking, 3rd Edition (Mary S. Smith, March 2020) is the accepted methodology behind such tables: it starts from each use's stand-alone peak demand, applies hourly presence factors from 6am to midnight, then applies non-auto and captive-market adjustments, and jurisdictions accept it as a starting point, frequently through proffers that require the shared supply to be re-checked over time ^[11].

Percentages of each use's stand-alone requirement, by time period ^{[12, 4, 5, 13]}.

The tables reward pairings whose peaks fall at different hours. Baltimore counts office at 5% overnight and in the evening against residential at 100% overnight and 85% in the evening ^[12]; Clayton County counts retail at 95% on weekday days but restaurants at 100% on weekday and weekend evenings ^[5]. Lynnwood keeps reserved hotel and residential spaces out of the sharing and allows a 500-ft captive-market reduction ^[13].

Codes also cap what staff can approve administratively:

The minimums those tables reduce are themselves falling. NAIOP, citing the Parking Reform Network, counted more than 3,700 cities in 22 countries that had reduced or eliminated parking requirements as of August 2025, with over 100 removing all minimums ^[16]. The UCLA Institute of Transportation Studies put it this way in November 2025: "more than 100 U.S. cities have eliminated any requirements to provide a minimum number of parking spaces from their zoning code, with hundreds more lifting their parking requirements in key areas like commercial corridors and historic downtowns" ^[17]. The Parking Reform Network estimates roughly 20 percent of over 3,000 examined codes have abolished or reduced mandates citywide ^[18].

Where the uses sit on separate parcels, the sharing is recorded. Reciprocal easement agreements are recorded instruments that "set the terms, conditions, and obligations for the easements, restrictions, and covenants between owners" ^[19], and Hamilton Township's code requires a recorded shared parking agreement before a zoning certificate issues ^[15]. TxDOT allows lesser driveway spacing than its corner-clearance criteria only where shared access is established with an abutting property ^[20], so the plan shows cross-access to the neighbor even before the neighbor builds.

Podium, height and the fire lane

IBC 510.2 (2024) treats the podium and the building above as separate buildings for area, stories and construction type when the horizontal assembly is 3-hour rated, the building below is Type IA, shaft and stair enclosures through it are rated 2 hours (with a 3-hour-below, 1-hour-above exception), and the building above contains Group A, B, M, R or S occupancies ^[6]. NFPA 13 sprinklers are required below the assembly, NFPA 13R is allowed above where its conditions are met, and height is measured from grade plane in current editions ^[21].

That last point decides the site plan. The podium can cover the whole lot, but because height is measured from grade plane, the overall height still triggers IFC D105 aerial access ^{[21, 22]}. The 26 ft aerial lane is therefore usually the street or a fire lane along one long face. Where Appendix D is adopted, an aerial road is required once the highest roof surface is more than 30 ft above grade plane; it is at least 26 ft wide, sits 15 to 30 ft from the building parallel to one entire side, and no overhead utility lines may run over it or between it and the building ^[22].

Land value, not preference, decides between surface parking and a structure. As market evidence, surface stalls run roughly $3,000 to $8,000 per space and consume 300 to 400 SF each including drive aisles, above-grade garages run $18,000 to $35,000 per space, and underground parking runs $25,000 to $50,000 ^[23]. For the residential side of the stack, see multifamily site plans.

State laws that change the mixed-use program

These states have primary-source rules that change what a mixed-use plan must hold. Elsewhere the mix, the parking and the ground-floor rule are set locally.

Two effects reach the drawing. In Texas, a multifamily project in a mixed-use zone can drop the ground-floor commercial a city once required ^[24]; in Washington, the ground-floor commercial can be planned with no required parking of its own ^[33]. In California, a hotel component in a mixed-use project near transit still takes its local parking ratio, because the transit-area relief does not reach transient lodging in Los Angeles ^[38].

Approval path patterns

Oakland Park says qualifying Live Local projects must be approved "without discretionary review by boards or commissions" ^[41]. By-right status does not always end the negotiation: the American Enterprise Institute documents an Austin applicant who pursued a negotiated rezoning (C14-2025-0089) instead of the SB 840 route ^[42]. Staff reports on re-planned office land record the opposition themes such a rezoning meets: traffic, school capacity, neighborhood character and building height, and municipal tax-base loss ^[44].

The concept stage is where an unsealed plan is asked for. Murfreesboro's due diligence meeting text reads: "A dimensioned conceptual site plan is required depicting all proposed and existing structures, vehicle and pedestrian access, parking, landscaping, potential drainage area(s) and a site data table" ^[43]. A due diligence meeting must be held before a pre-application meeting can be requested, and plans at the pre-application meeting should be "90-95% complete" ^[43]. Tennessee's board rule requires working or partially completed plans, and drawings that are not construction documents, to be designated preliminary, not for construction, for review only or draft (Rule 0120-02-.08(9)) ^[45]. See preliminary vs final site plans and where unsealed site plans are accepted.

One district's numbers: Murfreesboro's MU district

Murfreesboro, Tennessee has had a mixed-use (MU) district since a 2013 ordinance, and its Chart 2 standards show what a district table does to a mixed-use parcel. The values below are from the Chart 2 edition updated August 31, 2017; Chart 2 and its endnotes were amended by Ord. 26-O-13, passed May 21, 2026, so they are rechecked at due diligence ^{[46, 47]}.

Next to single-family land, a 4-story MU building takes a 40 ft rear yard under the 2017 endnote ^[46]. On an arterial or collector, the 2013 ordinance reads: "The minimum front yard set forth on Chart 2 shall be required unless the property abuts a major arterial, minor arterial, or collector street identified as such by the Murfreesboro Major Thoroughfare Plan as ... minimum front yard shall be 50 feet" ^[48]. On those frontages the building steps back and the front of the lot goes to parking and landscape. The state layer is on Tennessee site plans, and Murfreesboro sits in the Nashville metro.

Where mixed-use sites come from

Many mixed-use sites are re-plans of something else. In Johns Creek, Georgia, the State Farm campus (500,000 SF of office) was demolished for the $560M Medley mixed-use project, developed by Toro Development ^[49]. In Texas, SB 840 gives owners of office, retail or warehouse buildings at least five years old a by-right path to residential or mixed-use residential ^[24]. The office side of that story is on office site plans, and the Atlanta metro page carries the regional context.

What the preliminary plan carries, and what the engineer of record adds

The general split is in who prepares a site plan and do I need an architect for a site plan.

Related pages

Mixed-use programs overlap with hotel site plans where a hotel shares the parking, with senior living site plans where care units sit over retail, and with apartment rendering for the street views design boards ask to see. The studio's article on mixed-use redevelopment of shopping malls covers the retail-to-mixed-use case.