Assertion: rafter's end | /r/CapableOf | attach perpendicular
Facets:
value: at the 20-foot-long walls
type: LOCATION
Source sentences:
text: For example, if a room or section of a building is 20 feet long by 14 feet wide, the lower ends of opposing pairs of rafters attach perpendicular at the 20-foot-long walls, and the upper ends rise to a ridge above the center, or 7 feet from those outside walls.