Building/ Construction pack
Pack idea:
When you exit build-mode after spending a set amount of money or higher (e.g 5000) a pop up will appear with 2 options. One being "continue" which would allow you back into the game as normal. The other option being "hire builders" or "hire professionals" if you select this option, it will allow you to hire builders to construct the plans you have just created in build mode. The "fee" would show you how much extra cost it would be, and there would be a line in the same pop up letting you know how long the construction work would take (my suggestion is to be between 2-6 days so it doesn't drag on) The following day a small construction team would put up scaffolding around your area off work and build until its all complete. In this time, your sims will have moodlets based on the change. e.g: the noise could make them angry, the excitement of the build starting could make them happy. Once everything is complete your sim will also have moodlets based on the change.
This is a great idea because its unrealistic if I make a large extension on my sims house and its complete at a click of a button and my sims feel nothing about it. There should still be the option for it to remain like this but also give you the chance to hire people to build it for you.