How big is house head zise is around the Whole House/Head, the brain would be on the roof/upper part of the inland/inside of their heads/houses, their skulls may be the Own House, which may be hiding its skull on the inland/inside of it, and anything else, its size is approximately 30 meters.

Thank to Trevor for the House Head entity.

Real House Head are made out of old wood. The House/Head is connected/joined/united to an Long Neck made out of Old Wood, as said before. Also, if you look well at the first House Head, you can see an possibly Layer of its body, under the neck/body and between the limbs, which can be its probably Belly/Underbelly/Abdomen/etc.

Now House Head is an entity that live in Backrooms level 0.
Level 0 means the tutorial level for backrooms. You accidentally can go to the Backrooms by noclipping out of reality.

Thanks for playing our game!