Enter the real-world length of the line you just drew.
Useful for stacking floors: line the stairwell or an outer wall up, then place risers and outlets where they meet. Say which floor is which and the Wi-Fi prediction carries the signal through the slab.
The wall takes its thickness out of the middle, so an even split leaves both parts the same size.
Walls are found by looking for dark pixels in the plan image.
Turn off to tuck a chair under a table or put a rug beneath a sofa.