Another option

Create a terrain where you want your house :
just create a flat area in the terrain , and create a model constitued by
- a piece of terrain
- the house glued to that piece of terrain (easy a boolean object operation can do the trick)

after that place the model(piece of terrain with house) on the flat terraine area and modify your real terrain to fit well with the model.

i don't know if someone has understood the idea