Resources: How the BOMA 1996 Standard Works

Area Calculation

The BOMA 1996 standard is designed so that a landlord is able to charge rent for all the area in a building. This is done by 'grossing up' the usable area that a tenant has inside their suite by a factor that accounts for a proportionate share of the spaces that the tenant shares with other tenants: the common areas in the building.

Area is calculated in several steps:

1. First the building is surveyed and drawn up on CAD.
2. Usable space, common areas and vertical penetrations are delineated according to specific rules.
3. Vertical penetrations such as elevator shafts and stairwells are subtracted from the area of each floor.
4. The usable area of each suite is calculated.
5. A ratio between the total area of the floor and the total usable area within suites on the floor is calculated. This is called the floor R/U (rentable / usable) ratio.
6. The usable area in each suite is grossed up to arrive at the floor rentable area.
7. A ratio between the total of all the floor rentable areas and the total area of the building including building common areas such as the lobby and mechanical spaces is calculated. This is called the building R/U ratio.
8. Finally, the floor rentable areas of each suite is grossed up by this building R/U ratio to arrive at the Rentable Area.

It sounds complicated, but it is quite rational and logical. The standard uses a spreadsheet that performs these calculations from left to right so that it is easy to follow. We use a colour coding system that helps you relate the areas on the drawings to the cells in the spreadsheet. Once we've set up a building for you, we will spend all the time necessary to explain it.

Here's what it looks like. We colour-code and label the areas on the drawing:

These areas correspond to the columns in the spreadsheet.

For more detailed information, you can purchase a copy of the standard from BOMA here. It is clearly written and has several good illustrations.