The document discusses the characteristics and hazards of ordinary construction, which commonly uses masonry exterior walls and combustible interior walls and floors. Specific issues addressed include structural instability of masonry walls; void spaces that can accumulate combustible gases; interior structural elements like wood beams that can compromise wall stability; and roof types that often have little fire resistance and are susceptible to early failure. The document provides details on identifying signs of instability and planning firefighting tactics for ordinary construction buildings.