June 2017
I am trying to build a basement for my sim Lisa Smith. She lives in sunset valley at 58 Water Lane. So far I have added a burglar alarm next to the front door of the house. I don't want to destroy her home just to rebuild it with a basement. I don't have World Adventures or Patch 6(the one that gives you the basement tool) installed so I am wondering how I can build a basement for this preexisting home without destroying it and without using the basement tool. I can build a second floor just fine but I am stuck on how to build a basement. How can I build a basement without the basement tool?
If it means building a new lot, I could do that but I would rather do it on her already existing home so that she doesn't have to move in order to have a basement.
June 2017 - last edited June 2017
The only thing I can think of would not work on a existing building. But you could use the terrain tool to either lower or raise the terrain, do it to the same height as a wall (place one section of a wall outside of the area you are changing the terrain height - to use as your guide for height) and then also lower/raise the terrain for the size you want the basement. I think you would have to make it a walk-out basement because it will technically be your first floor without the use of the basement tool. (I am not sure if your second floor with a door would count as the main front door sims auto go to or not - you will have to test that out - unless someone on the forum knows and replies also)
I have also found some really good videos about building info, tips, etc. by just googling what I am trying to build. You should check it out - there are some really talented simmers with amazing builds. (be sure to include sims 3 in your search title otherwise you will get information pertaining to the other sims games
Wish I could help you more
June 2017
Before the patch and pack came along basements where built using the foundation tool search carlsims3guide they may have a tutorial up
Do however before you start building a basement save your game then save as new name if it messes up then you will still have your original save safe and untouched