Treehouse Series: Books 1-4 by Andy Griffiths (HC)

Set includes:

The 13-Story Treehouse, The 26-Story Treehouse, The 39-Story Treehouse, and The 52-Story Treehouse

52 Storey Treehouse:
Andy and Terry's incredible, ever-expanding treehouse has thirteen new storeys, including a watermelon-smashing level.

39 Storey Treehouse:
They've added a chocolate waterfall you can swim in, a volcano for toasting marshmallows, a bulldozer-battling level, a baby-dinosaur-petting zoo.

26 Storey Treehouse:
There are now thirteen brand-new storeys, including a dodgem-car rink, a skate ramp, a mud-fighting arena, an antigravity chamber.

13 Storey Treehouse:
It's got a giant catapult, a secret underground laboratory, a tank of man-eating sharks and a marshmallow machine that follows you around and shoots marshmallows.