Crashing after building walls

I've had this problem for the last few days. Every time i try and build one side of a room on the 3rd florr of the house i'm building at the moment, it freezes and then comes up saying the sims 4 has stopped working. i have lots of RAM and memory on my laptop, and i have no extra add ons or content on the game and its fine when i build in other buildings. Please can you help me as its hard for me to carry on playing without part of the wall.

Thank you,

Ellie