Newer buildings are made of new composites to make them stronger and more cost-effective to build. One of the features of these materials is it is able to insulate the building. Also, the materials can block RF signals from getting into and out of the building.
While RF blocking may be good for some purposes, it wreaks havoc on radio and cellular communications for public safety departments. Many states are enacting laws requiring buildings to have in building repeaters (bi-directional amplifiers). These will boost the signals and usher them to the outside world.
Many new constructions are installing an FCC compliant bi-directional amplifiers (BDAs) during the build. While buildings can be retrofitted with a BDA, sometimes the layout of the rooms in the buildings make retrofitting the building more difficult and cost more.