p r o c e s s i n g

2. Polystyrene

The first level of insulated door core is that polystyrene that may be a slab of foam that's placed within the core of the door. Hollow metal doors with this core sort square measure most frequently used at exterior openings and might be fire rated up to three hours. The insulation price is way on top of the honeycomb however below the polyurethane.

3 Polyurethane

This insulated core may be a foam that's injected into the core and expands to fill all the on the market house at intervals the cavity of the hollow metal door. polymer can have the simplest insulation worth that's more than each honeycomb and vinylbenzene. However, a polymer door can't be fireplace rated.

4. Steel Stiffened

Steel stiffened hollow metal doors have steel channels that run the complete height of the door and square measure spaced concerning O.C. across the breadth of the door. they're spot welded to the faces and therefore the gaps between the channels is full of insulation. These doors square measure usually such at high abuse square measures or are often used at openings wherever sound transmission ratings are a priority