Class H buildings (a subset of Class D) are characterized by combustible, prefabricated wood-post and tubular steel, semicircular, framed roof in a hoop (Quonset) shape. The roof curves to a short wooden pony wall or to the ground. The roof and walls are generally covered with canvass or a woven vinyl tarp. Ground floors are typically dirt or can be a concrete slab.
Construction Type V (wood-frame) of the Uniform, Type IV Basic and Type VI Standard Building Code are included in this class, as are ISO Class 1 buildings. This class is also referred to as Unprotected-protected One-hour Construction.