BOMA Z65.6 Mixed-Use Measurement: 2026 and 2021 Editions

ANSI/BOMA Z65.6 is the BOMA standard for measuring a whole mixed-use building: it splits shared lobbies, elevators, mechanical rooms and parking among the retail, office, residential and other components in proportion to their size. Individual suites are still measured with their own single-use standard. The current edition is Z65.6-2026 (released July 2026); many existing leases and declarations still name Z65.6-2021.

Today’s real estate market is full of mixed-use developments - buildings that combine retail, office, residential, hospitality, industrial, or other uses under one roof. When a property doesn’t have one clear “primary use,” or when governing documents (restrictive covenants, ground leases, or condominium declarations) require it, the ANSI/BOMA Z65.6 Mixed-Use Standard applies.

This measurement standard is not for measuring individual tenant suites.

Rule #1: For any single unit (apartment, retail shop, office suite), always use the specific single-use BOMA standard that best fits that unit’s primary purpose (Z65.1 Office, Z65.5 Retail, Z65.4 Multi-Family, etc.).

Z65.6 is used exclusively for full-building measurements to create fair, proportionate allocations of shared Mixed-Use Common Areas across the different use components throughout the entire building.

Here’s the clear, step-by-step breakdown every owner, developer, property manager, appraiser, and lender needs to know.

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When should you use the BOMA mixed-use standard?

Apply this standard when:

• The building has no easily identifiable primary use (e.g., 40% retail + 35% residential + 25% office), or the owner, tenants and lenders can’t agree on one.
• The property’s governing documents classify it as mixed-use.
• You need to allocate shared lobbies, elevators, mechanical rooms, loading docks, amenity decks, or parking fairly among different use types.

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What are the three steps in a Z65.6 measurement?

Step 1: Establish the Mixed-Use Boundary Area

Measure the entire building (or defined mixed-use portion) using the BOMA Gross Areas methods (ANSI/BOMA Z65.3) the Mixed-Use Standard is built on. This creates the overall “Mixed-Use Boundary Area” (the total gross area from which everything else flows.)

Step 2: Subdivide the Mixed-Use Boundary Area

Break the total area into two main categories:

• Mixed-Use Components - the actual usable areas for each distinct use (Retail Component, Office Component, Residential Component, etc.). Each component is measured using its own single-use BOMA standard.
• Mixed-Use Common Areas - shared spaces that serve more than one use component (central lobbies, shared mechanical rooms, common corridors, amenity spaces, structured parking that serves multiple uses, etc.).

Step 3: Handle Special Conditions

Address these key items that often cause disputes:

• Interior Door Setbacks should be treated consistently across mixed-use components. Interior door setbacks are a common building safety practice that moves swing doors out of the way of exit corridors so that they do not interfere with people’s movement in case of an emergency.
• Non-compatible Single-use BOMA Standards - when one component’s rules don’t perfectly align with another, the Mixed-Use Standard provides reconciliation methods. The Mixed-Use Common Areas are allocated first, in proportion to each component’s size. Each component’s share is then carried into the single-use BOMA standard (or other agreed method) used for that component, so every component ends with a consistent rentable figure.
• Parking Areas are to be allocated proportionately based on each component’s relative size (or per governing documents).
• Vertical Service and Circulation Areas (elevators, stairs, shafts) should be classified and allocated as Mixed-Use Common Areas unless they serve only one component.

The result? Every Mixed-Use Common Area is allocated proportionately to each component based on its relative size within the total Mixed-Use Boundary Area. This creates fair load factors and expense allocations for every use type. Load factor is the ratio of Rentable Square Footage (RSF) to Usable Square Footage (USF), where RSF includes the tenant’s USF plus a proportionate allocation of common areas. (See usable vs rentable area in commercial leases.)

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How does Z65.6 work on real buildings?

Three UrbanMeasure mixed-use projects show how the standard plays out.

Case Study 1: Downtown Mixed-Use Tower (Retail + Office + Residential)

A 180,000 sq ft building has 45% ground-floor retail, 30% upper-floor offices, and 25% luxury apartments sharing the same lobby, elevators, mechanical penthouse, and rooftop amenity deck.

Under Z65.6-2021:

• Step 1 establishes the full Mixed-Use Boundary Area.
• Step 2 measures Retail using Z65.5, Office using Z65.1, and Residential using Z65.4.
• Shared lobby, elevators, and amenity deck become Mixed-Use Common Areas.
• Allocation is strictly proportionate to each component’s size.

Result: The residential owner pays only 25% of the elevator and amenity costs instead of 50%, with a documented basis for accurate Common Area Maintenance (CAM) billing and condominium association charges.

Case Study 2: Suburban Lifestyle Centre with Parking Garage

A 320,000 sq ft property combines anchor retail, inline shops, and a small office component with a 600-space structured parking garage that serves all uses.

Under the 2021 standard:

• Parking is treated as a Mixed-Use Common Area.
• Allocation is based on each component’s relative square footage (or per lease terms).
• No single use “owns” the garage.

Result: Fair expense recovery for the developer; retail tenants don’t subsidize office parking, and lenders can clearly see proportionate load factors.

Case Study 3: Adaptive Reuse Warehouse into Live-Work-Create Space

An old industrial building is converted to 60% creative office/loft residential and 40% ground-floor retail/art galleries. The loading docks and vertical shafts are shared between all the use components.

Under Z65.6-2021:

• Non-compatible standards (Industrial vs. Retail vs. Multi-Family) are reconciled in Step 3 (Handle Special Conditions).
• Shared loading docks and vertical circulation are allocated proportionately.

Result: Clean, defensible measurements for lenders, tenants and the municipality, with clear documentation of how common costs are shared.

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What changed in Z65.6-2026, and is 2021 still valid?

BOMA International released the third edition, ANSI/BOMA Z65.6-2026, in July 2026. BOMA describes it as clarifying existing concepts, introducing new concepts and improving readability, while keeping the core method: proportionate allocation of Mixed-Use Common Areas to each Mixed-Use Component. The 2021 edition had already simplified the 2012 approach to a single allocation method. A lease or declaration that names Z65.6-2021 is still measured to 2021, and the edition used is always stated on the area certificate. We measure to Z65.6-2026 and to the 2021 edition when a lease names it.

The mixed-use standard delivers:

• Proportionate, transparent allocation of every shared dollar
• Fewer lease and condo disputes
• Stronger appraisals and financing packages
• Accurate benchmarking across truly mixed-use assets

Whether you’re developing a new vertical mixed-use tower, converting an old factory, or remeasuring an existing lifestyle centre, ANSI/BOMA Z65.6 is the BOMA framework for full-building mixed-use measurement. Use the edition your lease or governing documents name.

If this guide helped, see our pieces on measuring retail properties and office buildings. See also: CRU area certificates, industrial buildings, multi-family and hospitality.

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Mixed-use measurement FAQ

Does Z65.6 measure individual suites?

No. Suites are measured with their single-use standard (office, retail, multi-family, industrial); Z65.6 allocates the shared areas across the whole building.

Should we use the 2026 or 2021 edition?

Use the edition named in the lease or governing documents. For new documents, the current edition is Z65.6-2026.

How long does a mixed-use BOMA measurement take?

BOMA measurements and area certificates are typically delivered within three business days of the site visit. Large mixed-use buildings are scheduled with the owner.

How accurate is the measurement?

Every area is hand-measured on site to 1/10 inch.

Where do you work?

Calgary, Edmonton and across Alberta, British Columbia and Saskatchewan. Out-of-area travel fees apply.

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Why landlords and tenants use UrbanMeasure

Need help applying BOMA Z65.6 rules to your project? At UrbanMeasure, accurate property measurement has been a core part of our work for over 20 years, and our Calgary measurement technicians hold Architectural Technologist diplomas from SAIT. We are happy to review your floor plans, walk through the three-step process on a real mixed-use building, or explain how to allocate parking and vertical circulation fairly.

Our team specializes in hand-measured, professionally verified BOMA property measurements that comply with applicable measurement standards and reflect the conditions observed at the time of measurement.

In addition to measurement services, UrbanMeasure also provides:

• As-built drawings (CAD)
• LiDAR 3D scanning
• Commercial marketing floor plans
• Matterport 3D tours and commercial photography

By combining accurate measurement with high-quality visual marketing, we help real estate professionals present properties with clarity, confidence, and professionalism.

Get a quote for a mixed-use BOMA measurement · Calgary 403-827-4420 · Edmonton 587-598-4420 · Toll-free 1-844-504-4420 · info@urbanmeasure.com · Head office: 4034 16th Street SW, Calgary, AB T2T 4H4

Measure once. Allocate fairly. Maximize value and minimize disputes.

Written by Ken, BOMA Specialist / Architectural Technologist at UrbanMeasure.

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