## Measuring the area of a roof

In this chapter we will see how to calculate the area of a roof.

**Understand the perspective**

Obviously, when you look at a plan (paper or digital), you look at a 3-dimensional entity represented by a 2-dimensional drawing. It is important to specify the tilt of the measurements you will take so that e-Plans can measure the area in 3 dimensions.

Here is an example of a residential plan:

As specified in the previous tutorials, we will take the measurements of the roof as if it were a standard surface.

**Apply a tilt**

On the roof plans, you will always find the detail of the inclination, usually represented as follows :

**It is important not to include surfaces of different inclinations to the same extent.
2 slopes = 2 measurements.**

Select a measurement and go to the "**Properties**" toolbox in the left panel. Then select the "**Slope**" tab.

We will select "**Elevation**" since we have a front view. If we had had a high view, we would have chosen "**Plan**".

The blue arrow indicates that the calculation will be done in "Elevation" mode as requested. As specified on the map, we have a slope of 9/12. We therefore enter a height of **9** for a width of **12**. The angle of 36.87 degree is calculated automatically.

Before applying the slope (**370.46 ft²**):

After applying the slope (**617.44 ft²**):

You just have to apply the right slope to each of your measurements!