Use Dimension Shapes in Floor Plan
In the Floor Plans category, open the Dimensioning library.
Reposition the dimension lines and dimension text by dragging a control handle.
Note: To see a tip about a control handle for a selected shape, pause the pointer over the handle.
If you add a dimension to a wall, you can resize the wall by selecting the dimension shape, typing the dimension you want, and then clicking away from the dimension shape.
Read ultimate floor plan tutorial to learn more about the tool.
Click the following link to view the video tutorial: Video Tutorial - How to Create a Floor Plan
Add Dimension Lines to Walls
Drag a dimension line from Dimensioning library to a wall.
To perfectly align with the edge of the wall, you can drag a smart guide from the ruler for alignment.
From the floating button, it's easy to set the unit, precision, angle and extension lines options.