Extreme Measures Planmine™ Help Desk
About Us
Sign In / Up

Extreme Measures

This help desk is a free resource intended for discussion purposes only. Neither BOMA, its chapters, affiliates, or Extreme Measures Inc.® are responsible for the information, comments or opinions expressed herein. For complete information, refer to the official publications of the standards themselves.

FAQ & Read-Me Articles
What are as-built drawings / models?
What is CAD and BIM?
How do I resolve an area dispute?
Where can I get measurement standards publications?
BOMA Office Overview
BOMA Industrial Overview
BOMA Retail Overview
BOMA Multi-Unit Residential Overview
BOMA Gross Areas Overview
BOMA Mixed-Use Overview
IPMS for Office Overview
Alternative Methodologies
Glossary of Industry Terms

Exterior/Construction gross areas

Dominic Tremblay
August 30, 2011

I have the plans for an older building (meaning no curtain wall) as you can see at this link:

I traced a blue and a green line to show two possibilities. Which one should I use for building perimeter (cga) and/or for building line (ega).

Is there a difference if this floor is the ground floor or an upper floor?

Is there a difference if the windows are recessed for the full height of the building or there is smaller recesses for each floor of the building?

Thank you.

David Fingret
Extreme Measures Inc.
August 30, 2011

Hi Dominic,

In this scenario, both the EGA (Exterior Gross Area) and CGA (Construction Gross Area) should be measured to the green line.

There may be a difference from floor to floor if there are unenclosed areas such as a balcony, terrace or colonnade. If so, then such unenclosed areas would be part of the CGA but not the EGA.

The measure line is the outermost structural or architectural surface of the exterior face of the building. If the windows are recessed and have a ledge on the outside, you would measure to the blue line.

Dominic Tremblay
August 30, 2011

Thank you for your answer David.

I suspect that these plans were misdrawn because when I look at the photo, the windows look recessed and should then present a straight line on the plan flush with the building wall.

However, on the top floors, the recess seems to span for three floors consecutively. Should we contour the windows in this case? Or only for the upper two floors out of these three?

Thanks in advance

David Fingret
Extreme Measures Inc.
September 1, 2011

Each floor should be measured individually, so based on your description of the top floors, you should contour the windows. Without looking at the top three floors, I can't say whether only two or three should be measured this way.

Dominic Tremblay
September 2, 2011

Thank you David!

Your Comments ...

Please allow up to 24 hours for your question to appear after it is reviewed.