Sentence:  For more secure rooftop decks, a <WSD>ledger</WSD> (a joist mounted against the side of the house to support one side of a deck) is attached to the face of the house with perpendicular sleepers (wood planks laid horizontally at wide intervals) aligned with the roof rafters below. 
Meaning of the word marked with <WSD> tags:  A board attached to a wall to provide support for attaching other structural elements (such as deck joists or roof rafters) to a building.