Mastering Gross Floor Area (GFA)
and Gross Livable Area (GLA):

To kickstart our exploration, let's first focus on Gross Floor Area (GFA), a prevalent metric among Quantity Surveyors, especially when dealing with residential multifamily projects. So, what exactly is GFA?

In its most basic form, GFA refers to the total area of a building. This area is measured between the outside face of the external walls on all floors. However, any unenclosed areas do not form part of the GFA. Let's expand on this concept and explore the specifics of measuring GFA.

The Canadian Institute of Quantity Surveyors has outlined specific guidelines for measuring GFA.

According to these guidelines, the measurement is taken from the outside face of the enclosing walls on each floor. Interestingly, no deductions are made for partition walls, columns, pilasters, or openings within the floor area. This must include elements such as stairwells, elevators, ducts, and more, where applicable.

GFA plays a pivotal role in construction estimating, providing a more accurate calculation of building construction costs. When we talk about GFA, it's crucial to understand the inclusions and exclusions. Let's break them down for better comprehension.

GFA Inclusions:

• Crawl spaces with concrete floors and a floor-to-ceiling height of 2m or more
• Basement areas with a floor-to-ceiling height of 2m or more
• Future basement areas (only requiring a concrete slab on grade for structural completion) with a floor-to-ceiling height of 2m or more
• Floor areas that are structurally completed but need finishing work later
• Tunnels, trenches, and similar structures with a roof slab that is 2m or more from the floor
• Rooms below grade or sidewalk (e.g., transformer rooms)
• Duct shafts, columns, and other projections beyond the general face of the enclosing walls, as long as they extend vertically for the full floor height
• Dormers, bay windows, and similar elements that extend vertically for the full floor height
• Penthouses, including elevator machine floors within them
• Enclosed connecting links or walkways
• Finished rooms in roofs and attics
• Attached garages above and/or below ground level
• Enclosed exterior staircases and fire escapes
• Enclosed porches
• Balconies and mezzanines within the enclosing walls of the structure

GFA Exclusions:

• Crawl spaces without concrete floors and with a floor-to-ceiling height of less than 2m
• Tunnels, trenches, etc., with less than 2m headroom
• Exterior balconies and canopies
• Projections beyond the face of the enclosing walls that do not extend vertically for a full floor height
• Prefabricated doghouses on roofs
• Connecting links that are not enclosed
• Unfinished roof and attic areas
• Carports and exterior staircases, and fire escapes that are not enclosed
• Isolated chimneys and the portion of the chimney above the roof line
• Interior open courtyards, light wells, and similar spaces
• Porches that are not enclosed
• Exterior steps and landings, paving, patios, and terraces
• Areas enclosed with a roof but without perimeter walls
• Areas enclosed with perimeter walls but without a roof
• Roof overhangs and cornices

While GFA provides a broad understanding of a building's total area, Gross Livable Area (GLA) hones in on the residential sector's heart and soul – the livable and heated spaces. GLA includes areas such as bedrooms, living rooms, kitchens, bathrooms, and other rooms that residents can directly access and use.

GLA is calculated by deducting certain areas from the GFA. These areas usually include garages or underground parking, storage rooms, and mechanical and electrical rooms. GLA thus gives us a measure of the total habitable space within a property.

The use of GLA is essential in budgeting for finishing work and estimating the mechanical and electrical aspects of a residential building.