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Firestopping vs. Fireblocking

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Are you familiar with the differences between the products that are required for fireblocking applications vs. firestopping applications? Did you think they were the same? Did you know that the presence of a UL marking on a product’s packaging does not automatically make it suitable for firestopping?

It is important to ensure that you understand the fundamental differences between firestopping and fireblocking.

Firestopping is required wherever a fire-rated floor or wall separation is encountered, in multi-family residential and commercial constructions. Fire-rated separation walls are required to be between units, in multi-family residential constructions. Fire-rated floors are only required for buildings with three stories or more. While these are the general construction design rules, there may be exceptions.

During the construction process, penetrations are made partially through (membrane penetration) or completely through (through penetration) these fire-rated separations. This is done by the trades to run electrical wires and cables, plumbing pipes, HVAC ducts, and other mechanical items. These penetrations violate the original integrity of the fire-rated floor/wall system allowing the passage of flame, smoke, and toxic gases to move to other areas of the building in the tragic event of a fire.

In the early 1980s, ASTM (American Society for Tested Materials) established the “Test Method for Fire Tests of Through-Penetration Firestops.” This test procedure is known as “ASTM-E814” and has an equivalent UL test known as “UL 1479”. These test standards have been adopted by all model building codes in the United States and have established specific guidelines to address the penetrations made through the fire-related floor and wall separations.

As a result, manufacturers have designed and tested complete lines of firestopping sealants and accessories, educated architects, code enforcement officials, builders, contractors, and other construction industry personnel; about the importance and the proper application of firestopping procedures.

Fireblocking wood frame non-rated residential construction predates actual “through penetration” firestop testing standards such as ASTM-E814 and UL1497 by almost 30 years. All of the original legacy building codes (CABO 1&2 Family Code, BOCA, SBCCI, UBC, etc..) had prescribed applications and test standards for residential fireblocking and were synonymous in building code wording and intent. Since the inception of the International Residential Code (IRC) for One and Two-family dwellings, the wording of the building code has become more ambiguous, which has allowed room for a variety of tested products.

As a result, the acceptability of these products is open to interpretation and is ultimately up to the building code official or the Authority Having Jurisdiction (AHJ) approval. This has led to some confusion about what products comply with best building practices. As a result, the collateral damage of improperly used products has crossed over into multi-family and commercial firestopping applications.

Important determining factors for proper firestop applications are as follows:

  1. What does the fire-rated system consist of?
  2. What is the hourly rating?
  3. What are the penetrating items, and what are their sizes?
  4. What firestop product(s) have documented testing that meets the established criteria?

Balloon framing was a common structure for residential construction 60 years ago. This type of construction created large, open concealed spaces between each floor, extending from the basement or first-floor to the attic. Today, platform-framing or western-style construction has become the standard in residential dwellings. In this type of construction, the floor framing bearing is on load-bearing walls.

Because of this, there is no concealed continuous space through the story levels or floor framing. This type of construction creates a built-in fireblock from the ceiling to floor levels, also known as top-plates. The integrity of the wood fireblocks are violated when they are penetrated for the trades to run their wires, pipes, and other mechanical penetrating items. Therefore, it must be protected with material equal to or greater than the burn time of the wood top-plate.

Traditionally, the fireblocking code sections found in the building codes, that predated the international code council, required openings around vents, pipes, ducts, and other mechanical penetrating items, at the ceiling and floor level to be fireblocked with “non-combustible” materials. The term non-combustible is defined in The IRC (International Residential Code) as “Materials that Pass the Test Procedure for Defining Non-combustibility of Elementary Materials Set Forth in ASTM-E136”. Simply put, ASTM has a test standard that defines a non-combustible building material as a material that will not flame, smoke, or have significant weight loss when subjected to 1382˚ F.

Upon passing this test, a manufacturer can label their product or material as a “Non-combustible” or “ASTM-E136” tested product. Using an ASTM-E136 rated product fulfills the code requirements for fireblocking penetrations because the material was tested and demonstrated not to burn at far higher temperatures than the burn time and burn temperature of wood.

Today, the IRC defines an “approved” material as one able to resist the free passage of flame and products of combustion. This wording allows for ASTM-E814, ASTM-E136, and other approved materials to be used in fireblocking applications, based upon the determination of the code enforcement official having jurisdiction. However, ASTM-E136 products are not compliant with ASTM-E814 applications. It is important to check the manufacturer’s suggested installation procedures and to consult your local building department.

For more information on the differences between firestopping and fireblocking, or for help in selecting and installing firestopping and fireblocking materials check out our firestopping resources page or contact us.