WHAT IS FIRE STOPPING?
Fire stopping has a complicated definition. However, there are two key words to remember when discussing fire stopping.
- A through penetration is simply a hole that has been made in a fire rated assembly in order to run cables, pipes, tubing, etc.
- A fire stop system is simply a patching method used to seal the opening and restore the integrity of the original fire rating.
WHAT DO I NEED TO KNOW ABOUT FIRESTOPPING IN ORDER TO MAKE GOOD DECISIONS?
Every installer needs to know what product and tested systems best suit their application. If the installation is not installed in accordance with a specific applicable tested fire stop system or Engineered Judgment design, it is wrong.
WHAT SHOULD I ASK IN ORDER TO DETERMINE THE RIGHT SYSTEM?
- What type of construction am I dealing with?
- What is the hourly rating?
- What is the assembly made of and how is it made? Gypsum board? Masonry? Concrete block?
- How big is the opening?
- How big is the annular space around the penetrants?
- What type of penetrants am I dealing with? Conduits? Metallic or non-metallic? How many? How big? Pipes? Are they vented or unvented?? Cables? What type? How many?
- Are there any special considerations in this particular application?
- Will pipes move or vibrate?
- Is there any unusual expansion and contractions?
- Will there be a need to modify the penetrants frequently?
HOW WILL I KNOW IF I HAVE CHOSEN THE RIGHT SYSTEM?
This is a difficult question to answer. The best source for information is the manufacturers themselves. Additional information can be found in the UL Fire Resistance Directory (beginning with 1990 directory). It is important to understand however, that the UL systems show the limitations to the test and not necessarily the limitations of the products. Get to know the limitations of the products. Ask manufacturers for guidelines on the use of products including what limitations are there in way of annular space requirements, depth of material used, limits on size, number, and material of penetrants. Everyone is conscious of liability these days. Reputable manufacturers are generally honest about the limitations of their products. When in doubtÖask for help. The manufacturers of fire stop products have performed more fire tests than anyone else. When you have a question, take advantage of their knowledge and experience.
WHAT DO THE TERMS "INTUMESCENT," "ENDOTHERMIC," AND "ELASTOMERIC" MEAN?
"Intumescent" means that the material expands when exposed to fire or heat to fill a void in the penetration caused by the deformation or combustion of the penetration item. An "endothermic" product blocks heat by chemical absorption and moisture release. "Elastomeric" products are flexible and prevent passage of heat and gasses while permitting movement of the assembly.
WHAT DO THE RATINGS "T," "F," AND "L" MEAN?
A "T" rating indicates the amount of time (usually hours) it takes the temperature on the non-fire side of a fire-rated assembly to exceed 325° F above ambient temperature. An "F" rating indicates the amount of time (hours) that a fire-resistive barrier can withstand fire before allowing flame to pass through an opening. An "L" rating denotes the amount of air leakage (cubic feet per minute) through a penetration.
DOES AN "F" RATING (FIRE) WITHOUT AN "FT" RATING (FIRE AND TEMPERATURE) MAKE A FIRESTOP SYSTEM ACCEPTABLE?
North American Building Codes generally state that all fire stop assemblies penetrating a firewall or horizontal fire separation, in order to meet code, must have an "FT" rating not less than the fire-resistance rating for the fire separation.
If a fire stop system has an "F" rating of 2 hours and a "T" rating of 15 minutes, this assembly has an "FT" rating of 15 minutes, not 2 hours. The "F" and "T" ratings are not separable. The ratings are expressed as the lowest of both the "F" and "T" ratings, check with the local AHJ on the project to see if this separation will be acceptable. This will have to be determined on a project by project basis.
IF BOTH SIDES OF THE WALL ARE SPRINKLERED, DO I HAVE TO FIRESTOP?
Yes, because sprinklers do not address the passage of smoke and gases; fire stops do. In actual building fires, the majority of deaths (over 75%) are caused by smoke, not fire.
WHAT IS THE DIFFERENCE BETWEEN A FIRE SEPARATION AND A FIREWALL?
A fire separation is a construction assembly that acts as a barrier against the spread of fire. A fire wall is a type of separation that subdivides a building or separates adjoining buildings.
WHAT ARE APPROVED METHODS?
"Approved methods" is a general term that refers to fire stop systems that have been tested by an independent laboratory (e.g., Underwriters Laboratory) and which meets ASTM E-814 and or UL 2079 performance criteria.
WHAT ARE ENGINEERED JUDGEMENTS?
They are recommendations in which system/product manufacturers sometimes provide in order to meet actual field conditions that do not match any existing tested systems. These EJís are based upon internal test data and existing fire stop systems.