Code violations are common.
There are many kinds of code violations but below are those we see most often.
Incomplete Documentation
Homeowners who completed remodeling work that requires a permit, but never received it, or contractors that expanded the scope of remodeling beyond the permitted code, are subject to a fine and an injunction by the municipality until the violation is either removed or fixed. If fixed, the appropriate permit must be pulled.
Stairs
The most common violation is height and size - either from the bottom floor, top landing, or between each stair. Aside from wrongful installation, the cause can be unsuitable sub-flooring or too thick/thin hardwood boards.
Smoke Detectors
Smoke Detectors must be hardwired per code and once a single detector is triggered, all others must follow as well. Battery operated smoke and carbon combo detectors are sufficient only if operated by Wi-Fi and connected to same modem.
Incorrect Bathroom Venting
Unless a window to the exterior of an existing bathroom is present, an exhaust fan is most likely to be required for venting. Such a fan can be duct to the roof or side wall. This is usually inspected during rough electrical, reviewed on gut rehab projects, or in the case of fire "replace" jobs.
Weak joists & beams
Framing is crucial for the safety of any structure, and in some cases, too long of a supporting beam (mostly in basements) or too thin floor/roof joists can trigger a violation. This is mostly found in new additions on top of existing structure or old homes. Sometimes the homeowner would be required to engage a structural engineer to satisfy the municipality and we will execute the work.