[matthew fuller]

"As an engineer we were taught to use a 2.5 safety factor."

As an engineer in training I was taught that in civil engineering (bridges and such), the factor was 5. Early sixties.

[Alberta's Child]

It's a bit more complicated than that. There are different safety factors for dead load (the weight of the structure itself), live loads (the occupants), and environmental loads (wind, snow, earthquakes, etc.). And these safety factors vary for buildings and bridges, too.

Very few applications in civil engineering would use a safety factor of 5. In fact, structures tend to have lower safety factors than many other applications like mechanical systems, aircraft, etc. because the loads tend to be very predictable.

[OldMissileer]

As an engineer in training I was taught that in civil engineering (bridges and such), the factor was 5. Early sixties.

Back around that same time my Dad, an engineer and an architect, told me the same thing. On bridges and such they always designed in a safety factor of five.