I don't know which mission you are at. But i believe it's the one that you work for the cops and they ask you to get evidence.
For me, i just follow the brown trail on the map. There's one division which one of the road's exit is blocked by 3 barriers. Don't go that one, continue straight, you should reach the house.
By the way, it's only the 4th climb that i successfully reached the house. I kept falling off the mountain