To use: in your interior scene go to Append (*not Link!) and navigate to where you saved this .blend, go into Objects and select the mesh you wish to use, select Append and the mesh will appear in your scene.
Now all you have to do is place the corners where you need them and bridge the mesh between them. Using the mirror modifier can make placing easier, especially with the edgings.
In the preview images a Subdivision Surface Modifier has been added but NOT applied - you can turn this up, down or off as you need.
*Note: if you use the Link option you will be essentially using the original model, any changes you make in your project to the linked model will be saved to the original model - however if you use Append you are using a copy of the original and any changes you make will not effect the original model :)