Re: Help please (building The Sims 3)

@SenadorX I have tried to recreate your problem in my game, using the same house, and I have been able to expand the house in the corner that you have shown in your video, by drawing a new foundation and a wall on top of it. Due to the limitations of the game, you cannot use the 'drag' arrow to expand diagonal walls or walls connected to diagonal ones; that tool seems to work best with square, box shapes. Any new walls or rooms will need to be drawn manually.

In order to draw a wall in the place you have shown, you will first need to add a foundation. Go to Build Mode > Platforms, Foundations & Decks and select the Foundation tool. In order for the foundation to be connected to the house, you need to start drawing it from an existing foundation (one of the corners is a good place to start) so it ends up the same height. Then you can turn it into the shape you like and draw walls on top of it.