BOMA Area Measurement

Why the number matters more than it looks

Square footage is not a description in a commercial lease. It is a multiplier. It sets the rent, it sets the operating cost recoveries, and it usually sets several other charges that are calculated per square foot. An error in that number does not happen once, it repeats every month for the length of the term.

It is also one of the easier numbers to get wrong. Areas are commonly carried forward from an old marketing brochure or an original construction drawing, then repeated through successive leases without anyone re-measuring the space. Meanwhile the building has been renovated, demised differently, and had its common areas reconfigured.

A measured survey replaces an inherited assumption with a figure that can be shown to be true.

What BOMA is

BOMA is the Building Owners and Managers Association, and the BOMA standards are the most widely used method in North America for calculating floor area in commercial buildings. They exist to make the number consistent: without an agreed standard, two people measuring the same floor can honestly arrive at very different totals depending on where they decide the boundaries sit.

BOMA publishes separate standards for different building types, including office, industrial and retail, because the way space is used and let differs across them. The current office standard is the 2017 edition, published as ANSI/BOMA Z65.1.

One detail that catches people out: the standard permits more than one approach to the calculation, and the same building can produce different rentable figures depending on which is applied. That is why the method used should be stated on the deliverable rather than left implied.

The terms that show up in a lease

Three figures get quoted for the same space, and they are not interchangeable.

The relationship between usable and rentable area is the load factor, sometimes called the add-on factor. A tenant paying on rentable area should understand what that factor is and how it was derived.

What we deliver

We are the measurement layer. We produce the drawings and the area breakdown that the calculation rests on.

• Measured base plans

  Dimensioned floor plans captured at ±10mm, showing the wall lines and boundaries the area calculation depends on.

• Area breakdown

  Areas broken out by space so the totals can be traced back to the parts they came from, rather than presented as a single unexplained number.

• Layered CAD

  AutoCAD .dwg with the boundaries on their own layers, so the calculation can be checked, adjusted and reproduced by anyone reviewing it.

• Demising verification

  Where the demising walls actually sit, which is the boundary that most often turns out to differ from the lease exhibit.

• iGUIDE 3D tour

  A walkable record of the space, so a figure can be sense-checked later without another site visit.

• Multi-suite consistency

  For a whole building, every suite measured the same way in the same visit, so the numbers are consistent across the rent roll.

When it is worth re-measuring

Re-measurement pays for itself most clearly around a change: a lease renewal or renegotiation, a suite being demised or combined, a building changing hands, a major renovation, or a portfolio where the areas came from several sources over several decades and nobody is confident they were produced the same way.

It is also worth doing when the existing figure cannot be traced. If nobody can say who measured the space, when, or to which standard, then the number is not defensible, and finding that out during a negotiation is worse than finding it out beforehand.

Common questions

Do you certify the BOMA calculation?

We provide the measured drawings and area breakdown that the calculation is performed from, at ±10mm. Which standard and method apply to your building, and the judgement calls involved in applying them, sit with the owner, the property manager and their advisors. If your project needs a formally certified measurement, tell us when you book and we will be clear about what we do and do not cover.

Why is the rentable area bigger than the space we occupy?

Because rentable area includes a proportional share of the building's common areas, such as lobbies, corridors and washrooms, on top of the space inside your suite. The ratio between the two is the load factor, and it varies considerably between buildings.

Our lease says one number and the space feels smaller. Can you check?

Yes, and that is a common reason to call. A measured survey establishes what is actually there. Whether a discrepancy has any contractual consequence depends on your lease, which is a question for your lawyer, but you cannot have that conversation without a reliable measurement first.

Can you measure a whole building rather than one suite?

Yes. Measuring a full building in one engagement is usually the better option, because every suite is captured the same way at the same time, and the resulting figures are consistent with each other across the rent roll.

Does this work for industrial and retail as well as office?

Yes. We work across commercial and industrial property, including warehouse, flex and retail space. BOMA publishes standards for different building types, and the measured base data we provide supports whichever one applies.

Keep reading

• As-built drawings — The wider drawing set that measured area figures come out of.
• Tenant improvement as-builts — Documenting a suite before a fit-out, including the demising line.
• Warehouse case study — Measured areas and clear heights on a real Surrey industrial building.

Put a number on the space you can actually defend

Book a measured survey online with an instant estimate. Plans and areas in one to two business days.