Above, a Montenegrin bridge being repaired in 1920 from damage resulting from World War I.
In the course of investigating a building, you will find any number of conditions that deviate from whatever platonic ideal of a building you have in your head. Those deviations can be described a lot of ways, generally negatively: they are obsolete construction, damage, inadequacies, and so on. A deviation that is commonly found but that people tend to not treat the same way is that some portions of a building may be stronger than needed. For example, I often end up discussing “excess capacity” of old steel beams when I write reports.
There is an unfortunate tendency for engineers to treat all deviations as problems that must be fixed. For example, current practice is to provide some level of reinforcing in pretty much all masonry walls, so old unreinforced walls are described as “not meeting code.” The phrase “not meeting code” is to some extent useless when examining old buildings: every time building codes are revised, a large percentage of existing buildings that met code requirements when constructed suddenly do not meet code. Code requirements are meant for new construction. They can be used to analyze existing structures, but to say that any deviation from current code is a flaw that has to be fixed is to say that the entire built environment has to be partially remade every few years to meet new codes.
An interesting case is when there are deviations that are damage of a kind that is common and therefore has a known form of repair. If a steel beam in an old building is overloaded, perhaps by a change of occupancy that increased the live load, it’s a fairly straightforward piece of work to increase the capacity of the beam by welding on some reinforcement. If wood joists are damaged, they can be sistered or replaced, which again are common and well-known repairs. There is a long list of common repairs that can restore strength, stiffness, and resilience to old structures, some of which barely rise above the level of maintenance. Poor mortar joints greatly reduce the capacity of brick construction, but can almost always be addressed via ordinary repointing. Finding deviations of this sort – which can legitimately be called “damage” – is meaningful. but not necessarily all that severe, as the damage can be repaired. In other words, brick that has loosened because of deterioration of the mortar both reduces the structural capacity of the building and is potentially dangerous, but it is not a terrible problem because the repair is known and simple. All damage is somewhere on a continuous spectrum between good condition and near collapse, but I see reports that treat damage as a binary condition: something is safe or it is unsafe, with no condition between the two extremes being given much thought. That oversimplification can be used as an excuse to demolish repairable buildings.
