If you need additional security for the doors on your premises then exterior metal doors are the best solution. If the existing doors are timber type without any glazing you could probably up grade. This would involve placing extra locks on the doors. The frame is usually the weakest point with a timber door. More often than most, the frame will break first if forced. So in addition to the extra locks you will need to strengthen the frame. This can be achieved by fixing a steel strip on the inside of the frame in front of the lock keepers.
The strip should be bolted right through the frame and held with anti tamper bolts. In addition to this “dog” bolts should be fitted to the hinge side of the door. Dog bolts are small, steel stubs, about ¾” long that will protrude into receivers in the frame when the door is closed. These will prevent an attacker having a go at the hinged side of the door.
If upgrading the existing door will not meet the new security needs, then replacing the existing door and frame with a new security door set is recommended. These doors are constructed with a steel inner frame and wrapped in a steel sheet. The joints of the steel sheet are either welded or folded. The whole unit is hot dipped galvanised to protect against corrosion. The door frame is also made from folded steel and is security fixed into the structural opening at a minimum of 8 points. These doors are quite heavy about 40 – 50 kg/m2 so it is vitally important the surrounding walls are strong enough to carry the load.
The door core can be solid wood for additional security or another filling such as honeycomb material making the door lighter.
Vision panels can also be installed in exterior metal doors like these. They consist of many layers of laminated glass held in position by a purpose made steel surround frame and bolted straight through the door using anti tamper bolts.
Obviously, with a security door the locking system is very important. Multi point locking will make the door very secure. These systems will lock the door along the leading edge of the door and in addition, shooting bolts will project from the top and bottom of the door, engaging with the frame. Dog bolts on the hinged side will also be necessary.
As an alternative to exterior metal doors, you might want to consider a security screen door which allows you to keep the door you already have but can add a high level of security; some look very functional but you can also consider a more aesthetically pleasing wrought iron grill design if you prefer.