The Riga IIs Foundation Frame is a strong structure that you can anchor your greenhouse walls into. Each base comes with detailed instructions on how to secure it to the ground. The base frame is 6” high - it is not required, but is highly recommended. Attach this frame to the bottom of the greenhouse. The frame sits in the ground, but can also be mounted on top of a wood, concrete or brick frame/wall to provide 5” of additional inside height.