ridgepole(n = noun.artifact) ridge, rooftree - a beam laid along the edge where two sloping sides of a roof meet at the top; provides an attachment for the upper ends of rafters;
is a kind of beam
is a part of gable roof, saddle roof, saddleback, saddleback roof

   The timber forming the ridge of a roof, into which the rafters are secured. [1913 Webster]