Joist
A horizontal framing beam that supports a floor or ceiling.
Joists are the repeating horizontal beams — wood or engineered lumber — that hold up your floors and ceilings. You'll hear about them when hanging heavy items, planning a remodel, or diagnosing a sagging or bouncy floor. In basements and crawl spaces, watch joists for water stains, rot, or insect damage, all signs of a moisture problem overhead or below.