A Look at the UL Guide Information for Through-Penetration Firestop Systems: Angled Penetrations

Feb 20, 2018 by Gary Mason, Fire Protection Engineer

We all know UL systems are very specific in calling out the requirements that must be met in order to have a complete system. What you may not know is that UL allows for certain alterations to be made to the individual UL system, these approved alterations can be found in the UL Guide Information for Through-Penetration Firestop Systems (XHEZ GuideInfo).

The majority of UL systems are tested with the penetrating item passing through perpendicular to the wall assembly or floor assembly. There are some UL systems that allow the penetrating item to pass through the assembly at an angle which will be indicated within the individual UL system. The allowed penetrant angle is typically up to but not exceeding a maximum 45° from perpendicular.

The degree of angle is measured from perpendicular or 90° to the assembly. The figures below show the penetrant at 90° and at 45° from perpendicular. A perfect example of a UL system that allows for the penetrant to be installed at an angle through the assembly is W-L-1049.

For those systems that do not specifically allow for the penetrant to be installed at an angle the UL Guide Information for Through-Penetration Firestop Systems can be referenced. The UL Guide Information allows for an uninsulated penetrating item indicated as metallic pipe, conduit, tube, duct or cable, to pass through the wall or floor at any angle. The firestop system is to consist of a fill void cavity material (sealant, putty or mortar), the annular space must be maintained on both sides of the assembly and all other specific requirements of the UL system must be met.

For applications with an angled penetrant that do not meet the requirements of an existing UL system or do not meet the UL Guide Information requirements, we can consider the possibility of creating an engineering judgment for the specific field condition. Please do not hesitate to contact STI Engineering Services for additional information.