With drawing.tool there is a lot of flexibility while creating your building. One powerful option is to enter a known length while drawing both walls and lines. Here are the steps:
Start by selecting either line or wall from the Design Toolbar
Click once to place a start point
Move the cursor in the desired direction
Type in the length and hit enter
Note: for projects in IP the units of length are feet and for projects in SI the units of length are millimeters.