Los Angeles has one of the most diverse and aging building stocks of any city in the country. Mid-century apartment buildings, pre-war commercial structures, industrial warehouses converted to creative offices, and masonry buildings that predate modern seismic codes all coexist across the city’s neighborhoods. For owners of these buildings, the question isn’t whether the building will age. It’s whether the aging has reached a point where a professional structural evaluation is warranted. Here’s what our engineers actually look for, and when the signs mean it’s time to get an expert involved.
The Warning Signs
Not all cracking means a building is in trouble, and not all structural problems produce visible cracking. The challenge for building owners is knowing which signs warrant concern and which are cosmetic. Here’s how forensic engineers think about the indicators.
Cracking patterns are the most visible sign, and the most frequently misinterpreted. Hairline cracks in plaster and drywall are common in older buildings and usually reflect normal thermal movement or minor settlement that occurred decades ago. They’re rarely structural concerns. The cracks that warrant evaluation are the ones that tell a story about movement: diagonal cracks that propagate through masonry walls from window or door corners, horizontal cracks in basement or retaining walls that suggest lateral soil pressure, stair-step cracking through mortar joints in brick buildings, and cracks that are widening over time. If you can track a crack getting larger by marking it and checking back in a few months, that’s active movement, and it needs to be evaluated.
Settlement and foundation movement are often visible as sloping floors, doors and windows that no longer close properly, or visible gaps between the building and adjacent elements like porches, stairs, or addition walls. Some settlement is normal in older buildings and occurred long ago. But ongoing settlement, particularly differential settlement where one part of the building is moving more than another, can indicate a foundation problem that’s getting worse.
Deterioration of load-bearing elements is a concern that building owners sometimes miss because the damage is gradual. In wood-frame buildings, this means water damage, rot, or pest damage to structural framing, particularly at sill plates, floor joists near bathrooms and kitchens, and any framing in contact with soil or chronically exposed to moisture. In concrete buildings, spalling concrete that exposes corroded reinforcement is a sign of ongoing deterioration that will progressively reduce the element’s capacity. In steel buildings, corrosion at column bases, connection points, and any location where water collects can compromise structural integrity.
Water damage to structural components deserves its own category because it’s so common in older Los Angeles buildings. A roof leak that’s been dripping onto a wood beam for years can reduce that beam’s capacity significantly. Water ponding on a concrete parking structure can cause reinforcement corrosion that leads to concrete delamination. These conditions progress slowly enough that building owners may not notice until the damage is advanced.
LA’s Specific Risks: The Building Types That Need Attention
Los Angeles has identified several categories of buildings that present elevated structural risk, and the city has enacted mandatory retrofit ordinances for some of them.
Pre-1978 unreinforced masonry buildings (older brick, stone, and concrete block buildings that lack steel reinforcement) are among the most seismically vulnerable structures in the city. The city’s Division 88 retrofit ordinance, enacted in 1981, required strengthening of these buildings, and most have been retrofitted. But “most” isn’t “all,” and some retrofits that met the minimum standards decades ago may not meet current performance expectations. Owners of URM buildings should confirm that their retrofit is complete and evaluate whether the building’s current condition aligns with its expected performance.
Soft-story wood-frame buildings, typically older apartment buildings with large openings at the ground floor for parking or commercial space, can collapse at the weak ground story during an earthquake. The city’s mandatory retrofit ordinance has been working through the inventory of these buildings, but compliance timelines and the adequacy of completed retrofits vary. Understanding what these compliance requirements involve and how structural evaluations feed into the process helps property owners navigate their obligations and make informed decisions about their buildings.
Non-ductile concrete buildings (concrete frame structures built before the mid-1970s without the ductile reinforcement detailing required by modern codes) represent what many seismologists consider the city’s most significant remaining seismic risk. The city has enacted an inventory and retrofit program for these buildings, and owners of older concrete frame structures should understand where their building falls in that program.
What Happens During a Structural Safety Evaluation
When a building owner engages a forensic engineer for a structural safety evaluation, the process typically begins with a document review. The engineer looks for original construction drawings, any previous engineering reports, permit records for past renovations, and retrofit documentation if applicable. These documents tell the engineer what the building was designed to be and what modifications have been made.
The on-site evaluation involves a systematic inspection of the building’s structural system. The engineer examines the foundation, the vertical load-carrying elements (columns, bearing walls), the horizontal elements (beams, floor and roof framing), and the connections that tie everything together. They look for the indicators discussed above (cracking, settlement, deterioration, water damage) and evaluate each finding in the context of the building’s structural system and the loads it carries.
For seismic evaluation specifically, the engineer assesses the building’s lateral force resisting system (the walls, frames, or braces that resist earthquake forces) and evaluates its capacity against current code requirements or, more commonly, against a performance standard that reflects the building’s risk category. An apartment building full of residents is evaluated to a higher standard than an unoccupied warehouse.
The evaluation produces a written report that documents the building’s condition, identifies structural deficiencies, classifies the level of risk, and recommends next steps. Those recommendations might range from continued monitoring of a minor condition, to targeted repairs of deteriorated elements, to a comprehensive seismic retrofit, depending on what the engineer finds.
When to Act
Building owners sometimes defer structural evaluations because they’re uncertain whether the signs they’re seeing are serious or routine. Here’s a practical framework: if the building is showing signs of active movement (cracks that are growing, floors that are changing slope, new gaps appearing), the evaluation should happen now, not next quarter. If the building falls into one of the city’s retrofit categories and you’re not certain about compliance status, get an evaluation to understand your obligations and your risk. If the building has experienced water damage to structural elements, or if structural framing is visibly deteriorated, those conditions are progressive. They get worse over time, and the cost of repair grows with them.
The structural safety evaluation itself is relatively straightforward and far less expensive than the problems it identifies. For Los Angeles property owners with older buildings, understanding the building’s structural condition isn’t just prudent maintenance. It’s the foundation for every other investment decision about the property.
If you own an older building in Los Angeles and you’re seeing signs that suggest structural concerns, or if you simply want to understand your building’s seismic risk, a forensic engineer’s evaluation can provide the clarity that lets you make informed decisions about safety, compliance, and long-term investment.
