Hi, I have made a house in the modeller and I want to copy them side by side .... how can I do it, thank you.

By modeler-if you mean custom modeling: In the interface Hold the shift key and make a square around the entire project and group it together. Or group together certain parts. Save it. Then in the design interface /plane view go to favorites>uploads>customized models and place the item/items where you want them.