Exterior doors are often a first line of defense against burglary whether at home or the office. Choosing a metal door is one type of exterior barrier available. Metal doors often come with a choice of five different core types. Choosing the best one for your application depends on what you want from the door. Here’s more information about each type.

Steel Stiffened

Steel stiffened doors have steel bars or channels running through the hollow metal. The steel runs the entire height of the door. Each piece of steel sits about half a foot from the next across the door’s width. Insulation fills the channels between the steel bars that are welded in place. The best uses are for tampering sound transmission ratings and in high abuse locations.

Honeycomb

Special resins are used to harden the honeycomb shaped cardboard that fills these metal doors. The cost-effective door is often used in interior applications but can function for an exterior door. The durable core has up to a 3-hour fire rating and is heavy duty.

Mineral Board

Mineral board inserted into the hollow metal core of the door can help attain a specific temperature rise rating. For fire safety, people can pass by without feeling the heat of the fire on the other side. The door temperature ratings can range from 250 to 650 degrees.

Polyurethane

All the available space fills up with the foam injected into the door’s hollow core. The major drawback of polyurethane is it does not come with a fire rating. However, the material provides the best value for insulation of all the cores.

Polystyrene

Finally, the most basic metal door core is polystyrene. The inserted slab of foam is the most commonly used in exterior doors because of its high insulation value. The fire rating lasts up to 3 hours. Whichever door you choose, make sure it fits with the needed application and budget.