Help on making walls

[Lumaja]

Making a plan of my house from a drawing of the house to make alterations has the outside walls dimensions, use this dimensions to make this plan but things went wrong.

Made this plan with “tooltip” entering correct dimension wall sizes, I start on wall (top left) A=10.5 to the right
and ending on wall F=8.50, front left bottom to left top I see the this wall doesn’t met the beginning of the first correctly and when measuring the outside dimension are all wrong or not the same that I entered
Can you please help me how to do correct.
Thank you /home/luis/TRY - 01.png

[hansmex]

Luis,

The length of walls is measured at their center, not at the inside or outside.
So, a room of 400x400 cms with walls of 20 cms thick, should be drawn with walls of 420 cms.

Hans