You do not need to be a structural engineer to notice warning signs during construction, you just need to know what to look for, and to ask questions when something does not add up.
No visible material testing or certification
If you ask for concrete cube test results or steel mill certificates and receive vague answers or none at all, that is a significant red flag. Reputable contractors test and document as a matter of course, not only when asked.
Rushed concrete curing
Concrete needs adequate curing time, typically kept moist and undisturbed for a minimum period, before formwork is removed or the next floor's load is applied. If shuttering is being stripped unusually fast to "stay on schedule," the structure's long-term strength is being traded for short-term speed.
Reinforcement that does not match drawings
Before concrete is poured, steel reinforcement should be visible and should visually match the spacing and thickness specified in the structural drawings. If you have drawings in hand and the site does not resemble them, ask why before the pour proceeds, afterward, it is too late to verify.
No single point of accountability on site
If it is unclear who is actually supervising structural work day to day, or if you get different answers each time you visit, that is often a symptom of the fragmented-contractor problem, where no one individual is truly responsible for structural quality.
Trust your instinct to ask for a second opinion
If something feels off, it is reasonable to bring in an independent structural engineer for a one-time inspection before proceeding further. The cost of that inspection is negligible compared to the cost of discovering a structural problem after the building is complete.
