Use Brick Interior Walls

• Most modern homes utilize nonmasonry walls, which consist of wood studs or framing posts. Workers typically cover the interiors of these studs with plasterboard -- also known as drywall -- or plaster, both of which offer little resistance to bullets cutting through the air at high velocities. To increase safety you should construct interior walls from brick, concrete blocks or a similar masonry material. As Berzerker.net notes, while these types of interior walls will eventually crumble if a gunman fires repeatedly in the same location, the walls are considerably sturdier than their standard, stud-based counterparts.
  
  

Use Stucco Exterior Walls

• While siding materials like aluminum, steel and vinyl offer low-maintenance solutions for exterior walls, they are not very safe when it comes to resisting bullets. According to Berzerker.net, the best bullet-proofing solution for a home's exterior walls is stucco, both in its cement-based and epoxy-based forms. While not resistant to staining, stucco offers bullet resistance and is fairly easy to repair and repaint.
  
  

Upgrade Doors

• Common household doors are unable to resist the explosive impacts of bullets. Even doors with aluminum or steel exteriors tend to have layers of foam at their cores, meaning they cannot keep you safe from gunfire. And while you could purchase and install a specialized security door, an alternative option is to update an existing door by attaching protective plates. For maximum safety, Berzerker.net recommends installing armored, tempered steel on the front of the door. However, bullet-proof fiberglass and Kevlar panels are less expensive options. To make up for the added weight of the door, replace your existing door hinges with ball-bearing hinges or piano hinges.
  
  

Use Bullet-Proof Glass Windows

• Bullet-proof glass windows typically have panes that are an inch thick and frames that consist of durable metal, like steel. The panes consist of Lexan, which, as Purdue University notes, is a high-resistance polycarbonate that lab technicians create by reacting carbonate esters with alcohols. As a less expensive alternative to installing new bullet-proof glass windows in your home, you could install specialized, high tensile strength plastic films on the interiors of your existing windows. However, these films only provide protection against small-caliber guns. To maximize bullet proofing, you will need new windows.