Why do old factories have that classic “saw-tooth” roof design?
As David G says a the design is reliable and fault tolerant. But there is more to it. These buildings incorporate either a row of posts or supporting wall partitions that run under the low part of the “saw tooth”. Flat roofs with that much support would also be fault tolerant but much more costly to support the same loads. A large A roof would be much more costly because a large building would have to have a very high peek. If a building 30 feet wide has a peek height of 15 feet + wall height of 12 (27 feet) then the same style roof on a building 300 feet wide would be 150 + 12 (162 feet). The reality is that architecture also has trends. These structures are inexpensive to build from standard components, can be easily expanded (add a “tooth” at a time) and reorganized. They have fallen out of favour for all but temporary structures for two reasons. The row of supporting posts don’t allow for unobstructed wide-open manufacturing areas. Most importantly, having the rain water drain to t
