Adding Second floor over garage when house already has two floors


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Hello All,


Having a difficult time trying to figure this one out. I've done an as-built of an existing two story home with an attached 24' x 24' garage with a one story 6' x 12' mudroom entry between the house and garage.The mudroom is one step down (- 6 1/2") from the level of the main house. And the garage slab is - 27" down from the floor of the mudroom or minus 33 1/2" from the main floor of the house. I'm taking the existing 2 stall 24' x 24' garage and converting it into a two story in-law apartment. See attached photo. I'm adding a beam and framing a floor system off of the garage floor that will be level with the mud room floor which will leave a 19" crawl space between the bottom of the new floor joists and the existing concrete garage slab. I've gotten that far and I have my first floor walls built and I want to add a second floor to the area over the garage foundation only. When I select add new floor, the program asks if I want to add a new third floor . I'm guessing that the program thinks I want to add a third floor to the existing second floor of the main house but as I already stated, I just want to add a second floor to the new apartment (old garage). Can this be done, or do I need to delete the entire second floor off the main house and then start over and redraw the second floor of the house as well as the second floor of the apartment? I've looked in the forums as well as googled this question and I can't seem to find any answers. colonialADU.thumb.jpg.a0ff924af6bb134d16f1541fc00e9725.jpg

Thanks for your help.




Home Designer Pro 2018

Windows 10 Pro

HP - Intel core I7 2600 3.4GHZ



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You already have a 2nd floor, no need to add anything.


Switch to the 2nd floor, turn on Reference Display to show the walls below, and draw in your needed walls. 


Use the Align With Wall Below tool to perfectly align them.

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