Introduction To Intumescent
Georgia-Pacific has conducted fire door tests in positive pressure furnaces since 1993. During this time we have used various types of intumescent materials and various ways of installing intumescent materials into the opening.
Following is a list of the advantages and disadvantages of the three approaches we have explored. This list reflects our experience and many conversations with knowledgeable people in the fire door industry.
The choice of which of these options to specify on any particular job belongs to the architect or specifier. All three choices may, with the use of an approved smoke and draft gasket, carry an "S" label for all fire ratings up to and including 90 minutes.
Intumescent Free*
These door designs do not use intumescent at all, but have been successfully tested and approved for labeling as positive pressure certified assemblies. The only intumescent needed anywhere in the opening is concealed in the meeting edges of pairs. This means that no intumescent is used on the door frame either.
Advantages
- Considerably less expensive than openings that use intumescent
- Aesthetically pleasing
- Presence of factory installed intumescent in meeting edges is easily verifiable
- Greatly simplifies labeling and installation
- No liability concerns stemming from missing or compromised intumescent
- Wider range of hardware options than with concealed intumescent systems
Disadvantages
Frame Applied Intumescent
This refers to adhesive-backed strips of intumescent that are adhered to the surface of a door frame. Frame applied intumescents are exposed and vulnerable to intentional or unintentional damage in the day-to-day use of the opening.
Advantages
- Works with wide range of hardware options
Disadvantages
- Vulnerable to intentional or unintentional damage or removal
- Ongoing maintenance requirement equals hidden expense
- Complicates installation and labeling of opening (correct intumescent must be supplied to job and installed properly)
- Negative aesthetic impact
- May interfere with placement of smoke or draft seals and may inhibit latch operation
Concealed Intumescent
This is the practice of concealing an intumescent material within the door leaf itself. Our approach to this is to include the intumescent into the edge of the door behind approximately 1/4" of wood. This hides the intumescent from harm without limiting its performance.
Advantages
- Protected from damage in normal use
- No liability concerns stemming from missing or compromised intumescent
- Simplifies installation at job site – door arrives at job complete and ready to hang
- Presence of intumescent is easily verifiable
- Will not interfere with placement of smoke and draft seals or impact latch operation
- Aesthetically pleasing
- Intumescent is installed in factory setting – consistency and reliability
Disadvantages
- More difficult to obtain hardware approvals, especially with concealed hardware
