I used Excel several times to create architectural drawings:
1. Set column width equal to row height, 1 = 1cm or 1mm or whatever your base unit will be
2. Choose your column for the y-axis and a row for the x-axis
3. Define where you want to put your origin (mostly inner left corner of your drawing)
4. Create a formula based on the row number for x and column number for y, I mostly use ex. 20 1 2 3 4 5 6 7 8 9 30 1 2 3, make sure to also put the y scale on the first row
5. Use conditional formatting to draw helper lines, like every 10 for example, both horizontally and vertically
6. Use freeze window to freeze the labels of both axes
Now you are ready to start! Use cell border and cell fill color to draw.
Tip: if you don't want to calculate your new position use column() - column(ref cell) and you will now if you need to move more to the left or right.
Happy home renovation!