One of the many understated skills required from architectural designers is the ability to perform area calculations.

Area calculations are required at all stages of the project and are important for feasibility studies, compliance and design requirements.

Read on to learn the best practices and start calculating away.

In this post:

Objective
Types of Area Calculations
Methods

Scale Ruler + Calculator
AutoCAD
BIM Software
”What if there is no scale bar on my drawing?”

Documentation on Excel & Revit
Pro Tips
Conclusion

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Objective

To calculate area of spaces to determine feasibility of design aspects based on project design and compliance requirements.

In architectural drawings, the area of each room must be presented in the room tag
on floor plans for space and furniture planning.

Most building authorities require some form of documentation/declaration of specific kinds of areas.

Architects must be competent in these area calculations by taking full advantage of the technologies available to assist.

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Types of Area Calculations

Architectural designers are required to calculate various kinds of areas.

Here is a rather (non-exhaustive) list of areas that we need to consider:

You can view areas to be calculated in terms of scale and purpose.

One example is to consider site area for determine the maximum height of your building based on prevailing planning requirements such as plot ratio.

Another example is to consider fire code compliance requirements such as fire engine accessway length/coverage provision based on floor area.

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Methods of Area Calculations

Method 1 - Scale Ruler & Calculator

Here is the most basic method for simple rectilinear area calculations.

Start by placing a scale ruler over an printed scaled architectural drawing.

If the drawing states 1:50, use a 1:50 ruler.

The scale ruler should have numbers on it, signifying the actual length of that you are measuring, instead of paper units.

Once you have obtained the length and width, multiply these figures to obtain the area.

Method 2 - CAD Software

If you have an AutoCAD file of the floor/site plan at 1:1 scale, you can perform area calculations without the calculator.

You can simply draw a polyline demarcating the area boundary.

Select the polyline with your cursor.

Type PROP on the command line to reveal the properties panel.

Scroll down till you see Measurement > Area.

The area of the selected polyline will be reported.

Method 3 - BIM Software

At the detailed design stage, you can use your BIM software (ie. Revit) to report and perform area calculations.

With proper modelling of walls, room areas are automatically generated.

For general areas, you can use area boundary lines in Area Plans for Revit.

The benefit of Revit is that you can create a live schedule reporting areas, which you can subsequently filter perform additional calculations and/or export to Excel for documentation.

By the way, some building authorities now request BIM models to be submitted, for them to be able to view these area schedules quickly and understand the design - as each area reported is linked to the model.

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What to do when there is no scale bar on the drawing?

Find a reference object on the drawing (or request for a scaled version).

The first thing I look for is a dimension annotation. If there is one, you can get a normal ruler and measure over the dimension. The scale will be the ratio of the measured distance on your ruler vs the dimension printed.

If you have no dimension to refer, I will look for a door or chair to understand the scale.

Typical door width = 1m, typical chair width = 40cm.

Use the above basis to establish the scale and continue to measure for the area via Method 1.

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Documentation of Area Calculations

A table form is most commonly used form of documentation for areas.

It is shown via rows and columns, indicating some form of classfication/categorisation for further analysis.

For example, a room area schedule can have the room number IDs as rows and areas as columns.

You can choose to perform a simple addition of similiar area types (eg. occupancy types) and also present it in a pie chart as a percentage of the total GFA.

There are three ways to document areas:
Pen & paper, Excel tables and Area Schedules in BIM software.

1) Pen & paper

Draw a table with lines for rows and columns.

Write the room/space identifier in rows.

Write the area value corresponding to each room/space in a row under the 2nd column.

Use the calculator and write down the total area below.

2) Excel tables

Basic excel skills are a must for architects.

First, create an excel sheet.

Insert the room/space identifier in rows under Column 1.

Insert the area value corresponding to each room/space in a row under Column 2.

Use the Sum Function in Excel to calculate totals of values across cells.

Learn more about the function from a Microsoft tutorial here.

3) Area Schedules in Revit

Making room areas schedules is easy.

First you need to create the rooms in Revit by using ‘Room bounding’ walls.

Then create a new schedule under the Project Browser on the left panel of the Revit interface.

Select Room as the category of elements for the schedule.

In the next panel, select parameters such as room number, name and area to generate the schedule.

This is just the beginning, there is more stuff that you can do with these schedules - watch the video by Balkan Architect below.

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Pro Tips

1) Master all the techniques of area calculation.

Sometimes we do not have access to computer or a particular software to do our area calculations. Thus, you will need to be prepared to use manual methods.

2) Areas to be round up in 3 decimal places.

Sometimes, we are given areas that are not integers.
Best practice to to round up to the nearest 3 decimal place for accuracy.

3) Align area boundary lines properly.

For young designers who are proficient in Revit, we sometimes rely too heavily on the software to generate the area calculations.

Do check if the room areas are calculated based on wall center line or internal face.

Adjust accordingly based on the objective for these area calculations.

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Conclusion

Area calculations is an essential skill for architects as you will be doing at almost all stages of the building project.

I hope that this post gets you started on using both manual and automatic methods for your calculations.

Good luck!