I have been to two libraries - Regenstein and Crerar - within the first hour of them being open and both were being cleaned or having construction done during business hours. Most people go to the library to be in a quiet study area. When someone is drilling on the first floor of the Reg causing very loud vibrations to be heard throughout the entire library, it is very distracting. Similarly, vacuuming at Crerar while people are trying to study is quiet annoying.
Why can't this kind of work be done when no one is in the library - either at night or in the morning before they open? We expect that libraries be a quiet haven to do work and today, for some reason, the simple rule of being quiet seems to be ignored.
Picking a good time for construction work often seems like a trick question. There is no "good" time for construction work, there are just less bad times.
Generally, we try to schedule construction and cleaning during the early morning (before 8am), but sometimes the work bleeds over into normal operating hours or has to be done during the business day.
Also, we often ask contractors to defer noisy work until interim periods, like this week, when we assume fewer people will be in the library buildings. For example, we waited until this week to do some renovations in Ex Libris and install new wireless routers in Regenstein (which may be the source of the drilling you heard).
This aside, we apologize for the noise and inconvenience.