Avalon relaxes the vanilla house size check without removing it completely.

For house planning and resizing, your Carpentry skill is treated as if it were doubled for the size limit calculation.

That means 20 Carpentry behaves roughly like 40 Carpentry for maximum building size, so larger projects become possible earlier without turning construction into unlimited building.

Normal placement rules still apply, so you still need enough free space and clear tiles around the planned structure.