We can pretty much install a cubby house on most surfaces, as long as we can level it out somewhat. The cubby base has 3 long legs, approx 10cm high. This means that on dirt, mulch, toppings and some small stoned surfaces we can dig the legs in so that the entrance to the cubby is flush with the ground.
Otherwise, if you have a paved, concrete or other hard surfaces, as long as it is level we can sit the cubby on top and there will be a small (3 inch) step up into the cubby.