Not easy to say timeframe, depend on how much of the "old" one you can use, else it just to change styles, adjust the roof a bit maybe.
But i can say what i do
I have a base price up to 150 m2 and then add for every extra m2 above that, i calculate interior area on all floor, incl garage, deck etc. living space or not dont matter.
Base is 25 hour on a "standard" house + 4 min pr extra m2 above 150 m2
If it's less than 150 m2, i still use 25 hour as a base.
Then you need to think about if there is a lot of non standard things inside the drawing that will make you use more time, only you know.
I also charge 5 hour for drawing terrain lines on print ( hint draftpalette is nice
+ cost of electronic terrain map in dxf or dwg
Extrawork on terrain is a guess.
And then the "bad one", i charge 2 hour for a 3D pdf
Somtimes i win, sometimes i loos, but thats the game as i dont go on hour rate if i can avoid it.
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