I did a reconfiguation that required the additional drilling of just one hole. I took the 3 short for the bottom and moved 2 tall into the middle creating an additional platform I used the short and the mini step UNDER the back of the house ~ drilled a new hole and used the platform it created to secure the house in place.I used a tall and medium on the top ~ I will have to add some CARPET to 2 of the platforms because THERE IS NO GRIP AND THE CATS FALL OFF Mogi cant get after it like he does on his old tree ~ but all 6 get on it ~ and sleep ~ the extra platform I created makes it have 3 platforms and it's a super roomie platform under the house so they can play one from that plaform to the one cat in the house. The reconfig I did is way better ~ BTW