NFPA 13, a standard for the installation of sprinkler systems, defines unobstructed construction as a building structure that does not hinder the flow of heat or water during a fire. Obstructed construction, however, contains structural elements, like beams, that can impede heat flow and water distribution, affecting a sprinkler system's effectiveness. The standard provides specific guidelines for sprinkler placement based on these two construction types. These guidelines ensure that sprinklers activate quickly and effectively in both types of construction, minimizing the risk of fire damage.