Industrial Buildings: Why BOMA Z65.2-2019 Still Matters Today

Your Complete Guide to Gross Rentable Area & Key Rules

Warehouses, distribution centers, manufacturing facilities, flex buildings, and industrial parks all live and die by accurate square footage. The ANSI/BOMA Z65.2-2019 standard (released in 2019) brought a major overhaul: it replaced the old dual-method system (Exterior Wall Method A vs. Drip Line Method B) with a unified methodology. The Exterior Wall Method measured commercial buildings from the outside face of exterior walls, encompassing all floors, structural elements, and mechanical spaces, excluding unroofed areas and shallow (under 3-foot) ceiling heights. The Drip Line Method B measured a building's area to the outermost perimeter of the roof's overhang or projection.

This update in measurement standards delivers consistency, reduces disputes, increases defensible rentable area in many cases, and aligns better with International Property Measurement Standards (IPMS). Accurate application of these measurement standards directly boosts Net Operating Income (NOI), improves clarity in lease negotiations, and supports more accurate asset valuation.

Here’s the practical breakdown of the standard and its definitions to make measurements for leases easier for industrial owners, property managers, real estate brokers, and tenants.

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Gross Rentable Area (The Measurement That Matters Most)

Gross Rentable Area (also called Rentable Area) is the total billable space a tenant pays rent on. It equals the tenant’s Occupant Area plus their pro-rata share of common areas allocated using multiple Load Factors for different types of shared space. Occupant or Usable Area (UA) represents the actual space a tenant exclusively occupies and controls for their business operations.

Key Measurement Rule for Industrial Buildings:

Measure to the exterior face of the building (include the full thickness of exterior walls and cladding).
For shared walls between different occupant areas or amenity areas - measure to the centerline (midpoint) of the wall.
Qualifying areas under a permanent roof that support “industrial activities” (including covered loading docks and certain overhangs) are included.

Wall Priority Based on Space Classifications

When walls are shared, the standard applies a clear priority hierarchy to decide which space classification “gains” the wall thickness:

Major Vertical Penetrations (MVPs) / Parking / Floor Service Areas / Building Service Areas take priority over Occupant Area.
Occupant Area takes priority over Overhang Areas.
Shared walls between Occupant Areas and Amenity Areas are measured to the centerline.

This priority system prevents double-counting and ensures fair allocation in complex multi-tenant or flex industrial buildings.

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Space Classifications – The Heart of the Standard

BOMA 2019 cleanly categorizes every square foot in industrial buildings:

1. Floor Service Areas (serve only one floor).

[Please specify whether floor service areas are generally included or excluded in rent calculations]

Restrooms and associated shafts
Janitor rooms/closets
Electrical/telephone rooms
Mechanical/utility rooms
Multi-tenant corridors

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2. Building Service Areas (serve the whole building and are necessary for normal operation/circulation)

Main and auxiliary lobbies
Building access/egress corridors
Building mechanical or electrical rooms
Shared loading docks
Caged mechanical areas
Garbage rooms
Security rooms
Public restrooms
Building supplies and storage
Building operation rooms/offices

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3. Building Amenity Areas (non-permanent portions of the building that can be converted back to Occupant Area).

Shared conference rooms
Food service facilities
Health or fitness centers
Daycare facilities

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4. Major Vertical Penetrations (MVPs)

Stairs (including landings), elevators, escalators, flues, pipe shafts, vertical ventilation shafts, etc.

In the 2019 standard, the lowest level of MVPs is now included in Rentable Area (a change that often increases billable square footage).

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Practical Case Studies: Real-World Application of BOMA 2019

Case Study 1: Multi-Tenant Warehouse with Shared Loading Dock

A 180,000 sf distribution center in the Midwest has three tenants sharing a large loading dock and exterior canopy. Under the old Method B, the dock area was disputed.

Under BOMA 2019:

The dock is measured to the exterior face, and is classified as a Building Service Area.
The load factor is applied pro-rata to all three tenants.

Result: Rentable area increased by 2,400 sf with zero disputes — landlords captured additional revenue, tenants accepted the clear allocation.

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Case Study 2: Flex Building with Mezzanine and Covered Overhang

A flex industrial park in Dallas includes permanent mezzanines and a 1,800 sf covered overhang used for truck maneuvering.

Under BOMA 2019:

Permanent mezzanines are fully included [in what?].
The overhang qualifies for inclusion in rent calculations because it sits under a permanent roof and supports industrial activities - measured to the exterior and included in Occupant Area (with priority rules applied).

Result: The building’s total Rentable Area grew by ~4%, making it more competitive in the market and increasing NOI without additional construction.

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Case Study 3: Manufacturing Plant with Internal Service Rooms

A 250,000 sf food-processing facility has large mechanical rooms and restrooms embedded within the main floor plate (total horizontal floor area of a building's primary storey, measured from the exterior walls).

Under the new unified method:

Mechanical/utility rooms are classified as Floor Service Area.
They receive their own Load Factor applied only to that single tenant.

Result: Cleaner, more transparent calculations — no more arguments over whether service rooms “belong” to the tenant or the building.

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Case Study 4: Multi-Building Industrial Park with Inter-Building Areas

A 12-building park shares a central security building, trash compactor, and access roads between buildings.

Under BOMA 2019:

These are treated as Inter-Building Areas (now often called Inter-Allocated Areas).
Allocated pro-rata only to the buildings that actually use them.

Result: Tenants pay only for the shared space they benefit from — load factors are fairer, leases close faster, and the park commands higher rents.

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Why BOMA Z65.2-2019 Still Matters Today

Despite BOMA’s 2025 update, the 2019 standard remains widely used in leases, appraisals, and transactions across North America. Its unified method, multiple load factors, inclusion of lowest-level MVPs, and clear wall-priority rules make measurements more consistent and often more profitable than the pre-2019 rules.

Whether you’re remeasuring an existing warehouse portfolio, negotiating a new lease in a logistics park, or valuing a flex building, ANSI/BOMA Z65.2-2019 is the mandatory reference for industrial real estate.

See our companion pieces on methods of measurement for retail spaces and office buildings if you found this quick guide helpful!

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Why Lessors and Commercial Tenants Trust UrbanMeasure

Need help applying BOMA Z65.2 rules to your property? At UrbanMeasure, accurate property measurement has been a core part of our work for over two decades. We are happy to review specific floor plans, walk through load-factor calculations, or explain the difference between Floor Service versus Building Service Areas in a real warehouse.

Our team specializes in hand-measured, professionally verified 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:

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

Stay accurate. Measure once, lease with confidence! Maximize Value!

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