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Engineering Judgment (EJ) Request Guidance (US)

Posted by Jose Hernandezalmost 2 years ago

Request a more Accurate Engineering Judgment the First Time

Fire Protection Engineering,Engineering Judgments

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Fire compartmentation, a passive form of fire protection, is achieved using fire-resistant rated assemblies such as walls, partitions, or floors to separate building spaces. These barriers are designed to minimize the spread of smoke and fire from the area of origin to adjacent compartments. The effectiveness of a fire-resistant rated assembly is dependent on the inherent fire-resistance rating of the assemblies, construction methods, and other aspects such as openings that occur due to joints or penetrations.
Penetrations and joints in fire-resistance rated assemblies (gypsum walls, concrete floors, etc.) can be treated using tested firestop systems. These tested systems are documented and expressed in the form of listed or certified systems by nationally recognized independent testing laboratories, such as Underwriters Laboratories (UL), FM Global, and Intertek. As an example, a Hilti UL listing (W-L-1054) is shown in Figure 1. Listed/certified firestop systems should always be used instead of an engineering judgment when possible. A catalog of Hilti’s listed firestop systems can be found at Hilti.com/firestops


Figure 1: W-L-1054


When is an Engineering Judgment (EJ) Needed?


           When a listed or certified firestop system is not available for the specific project application, an EJ provides an alternative firestop solution to specifically address openings or voids within, or between, fire-resistance rated assemblies to meet code requirements. To help ensure accuracy and appropriateness of an EJ, Hilti follows the International Firestop Council (IFC) recommended guidelines for evaluating firestop systems in EJs. Visit https://www.firestop.org/ to find the specific criteria. Hilti’s Fire Protection Design Team (FPDT) uses data from years of research, fire testing, and existing listed systems, applying them to specific field conditions using sound engineering principles. If there are any specific local code requirements that must be complied with that are different from the requirements of the International Building Code, communicate this requirement to the Hilti Fire Protection Design Team when requesting an EJ.
 

Components of an Engineering Judgment:


           EJs can be as simple as a fire-rated wall with a through-penetration and sealant around the pipe, however, they can also be very complex and require multiple different views and firestopping materials. It is important to understand the necessary information for an EJ and accurately communicate to the Hilti Fire Protection Design Team, to ensure that the application and the solution developed align.
 
For EJs there are 6 major components that must be included when requesting an EJ. Engineering Judgments are contractor, project, and application specific:
1.    Job information (project name and contractor/designer);
2.    The F-rating (and T-rating, if applicable) required;
3.    Details of the substrate(s) (e.g. wall, floor, floor-ceiling, or roof/ceiling assembly), including the assembly listing number if available;
4.    If applicable the penetrating item(s) (e.g., material, size, etc.);
5.    The dimensions of any spacings, gaps, material thickness, etc. (e.g. annular space around the penetrating item, joint width between two assemblies, etc.); and
6.    The firestop material you would prefer.


 

Substrates/Fire Resistant Rated Assemblies:


As mentioned in item 3 above, important details to provide for the fire-resistant rated assemblies, or substrates, are as follows:

  •  The type of assembly, (Ex: gypsum wall, gypsum shaft wall, concrete floor, concrete floor over metal deck, etc.),
  •  The thickness of concrete (for concrete-metal-deck applications it is the thickness above the flutes of the decking), plaster, CLT, and heavy timber assemblies, and
  •  The width of studs being used in gypsum assemblies. 




Some assemblies will need to be accompanied by their fire-resistance rated design reference or listing, manufacturer provided ASTM E119 reports, or other standard specific performance report. These documents provide valuable information to the Hilti Fire Protection Design Team which will assist them to review the full scope of the requested condition(s) and requested fire resistance features.
For perimeter joint (edge-of-slab) applications, it is important to note as many details of the non-rated exterior façade as possible. Where possible, architectural files details of the perimeter joint condition should be provided. Ensure to note the slab edge thickness, the joint width and any unique, known conditions of the façade which may not be noted/visible within the photos or details.
It is important to note any limitations such as accessibility issues. While most listed systems require sealant on both sides of a wall assembly or the top side of floor assemblies, single side and underside installation methods are achievable in many cases.

 

Membrane or Through-Penetrations:


           Note that the difference between a membrane and through-penetration is that a membrane penetration only breaches one side of the wall or floor assembly. For either type of penetration, additional information required for penetrating items includes the following:

  • The material of the penetrating item(s) (e.g. steel, cast iron, copper, PVC, PEX, etc.);
  •  The maximum size of the penetrating item(s) (nominal pipe diameter or penetrant dimensions);
  •  The wall thickness of the penetrating item(s) (pipe schedule [sch] or the standard dimension ratio [SDR]) if applicable;
  •  The gauge of steel (for metallic items other than pipes);
  •  The types of cables, size of the cable bundles and the percentage of the cross-sectional opening or cable tray that they occupy;
  •  Any sleeve that may be installed (sheet metal sleeve, steel pipe sleeve, etc.), the extension of the sleeve, and the wall thickness of the sleeve (in gauge or sch);
  •  Whether the piping system is an “open” (unpressurized) or “closed” (pressurized) system;
  •   The insulation type (e.g. glass fiber, AB/PVC, cellular foam, etc.) and insulation thickness if applicable.



All information provided above plays a direct role in the solution the Hilti Fire Protection Design Team can offer. Within the construction industry, there are multiple types and varieties of piping. For combustible piping and insulation, small changes in the chemical make-up can drastically change the way pipes burn and degrade in fire testing. Due to these factors, it is critical to identify the specific piping material and/or insulating material (type, overall size and wall thickness) to help ensure the firestop solution provided is adequate.



Penetrant Spacing:


The opening size and annular space directly affect the type of firestop material that can be used for a given condition. Annular space is the distance from the penetrating item to the perimeter of the opening in the fire-resistance rated assemblies. For multi-penetrant installations, annular space also applies to the spacing between individual penetrants within the same opening/installation. The UL Guide Information for Through Penetrations clarifies that when a penetrant is installed in a rectangular opening, annular space is to be measured from the nearest edge of the penetration to the side of the opening perpendicular to that edge. Annular space is not to be measured diagonally unless measuring the distance between two penetrants in the same opening. Both the minimum and maximum annular space must be established, to determine if a given firestop solution would be expected to provide the needed fire resistance. When the annular space or joint width becomes too large, additional firestopping measures are needed to protect the annular space around the penetration.
When a penetration is in contact with the opening (min. 0’’ annular to opening), a bead of firestop sealant is typically required to be applied at the interface of the pipe and the opening. It is important to note point of contact to the periphery of an opening at a single point is not the same as continuous point of contact between a penetrant and the entirety of the opening (i.e. nominal 0’’ annular space). Continuous point of contact is only allowed by a few systems (e.g. W-L-1054 or W-J-1067) which include a specific note stating, “pipe may be installed with continuous point of contact.”
           For systems involving multiple penetrations, there are requirements for the annular space between penetrants, and the annular space between penetrants and the opening. The Hilti Fire Protection Design Team needs this information to accurately define a firestop solution and to account for any additional attachments that may be required for penetrations. (e.g. steel angles on a duct, a collar on a plastic pipe, etc.). 

Figure 2


Construction Joint Width:


Joint width is the measured space between two adjacent assemblies. These assemblies could be head of wall, wall-to-wall, floor-to-wall, bottom of wall, edge of floor-to-curtain wall or wall-to-curtain wall. Joint width can be measured different ways depending on what type of assemblies are being constructed. For example, with a gypsum wall assembly (Figure 3), joint width is measured from the edge of the gypsum boards to the adjacent assembly.
Another unique example for measuring joint width occurs with concrete over metal deck floor and roof assemblies. For these assemblies, it is important to note that the joint width is taken from the lowest point of the flutes, known as the valley of the flutes, to the top of the wall assembly underneath (as shown in figure 4). Providing the correct joint width is very important. As the joint width becomes larger, additional protection measures may be required. For example, a head-of-wall condition with a small joint width (typically 1” or less) may be detailed to show a sealant only solution. Once the condition has exceeded the  joint width capabilities of the sealant, the Fire Protection Design Team may add mineral wool and in extreme cases, steel cover plates.

The joint width is also a major variable when considering the movement of a joint system. The smaller the joint width, the smaller the available deflection. When the joint width is larger than the referenced system, the given linear deflection increases, and the percentage of compression and extension decreases. 



Requested Firestop Material:


It is common for customers to request a specific type of firestop for a given condition based on the product they might have on-hand or a preferred method of installation. It is important to note that there are conditions where it is not possible to achieve a fire rating with a requested product due to a lack of testing, compatibility issues, or feasibility of installation. When one of these issues arise, the engineer on the Hilti Fire Protection Design Team will reach out to the requestor to discuss any alternative solutions.
 

Additional Ratings Beyond Fire-Resistance:


Where additional ratings are requested to be noted/specified on an EJ, the Hilti Fire Protection Design Team will evaluate the presented conditions and provide notes or ratings where possible. These additional ratings could be a T-rating (temperature), L-rating (air leakage) or W-rating (water leakage). Please verify with local building code and/or project requirements on whether these additional ratings pertain to your project detail.
 

Requesting an Engineering Judgment:


This article has identified the essential information that needs to be included in an EJ request to the Hilti Fire Protection Design Team. Providing the necessary information in a request to the Hilti Fire Protection Design Team allows the engineer working on the EJ to provide an efficient, accurate solution. To request an EJ please visit: Hilti.com/ej




2 comments on this article
Posted by Jose Hernandez3 months ago
Hello Jackie, I have looked through our firestop UL listings (our tested and approved firestop systems) for blank opening through penetrations and we do not have any UL listings that will be able to address this size of opening. When you do not have a UL listing this is when you will need to request an engineering judgement since there is no direct testing for this application. Our Fire Protection Engineering Team does engineering judgments for larger opening sizes all the time so there should not be an issue creating an engineering judgement for this condition. Typically we end up adding a cover plate or wire mesh to the sides of the opening to accommodate the larger opening size. Engineering project and contractor specific so we do not have pre-made engineering judgements that we can provide you for this condition. You will need to request an engineering judgement through the Hilti Construction Platform. To signed up on this platform please got to Hilti.com/ej or Hilti.ca/ej.

Posted by jackie carrillo3 months ago
is there an UL engineering judgement for patching a 24x36 openings in a 2-hour fire rated wall?