RTUD and ATUD Now UL Listed As a Through-Penetration Firestop System
The Simpson Strong-Tie take-up devices (RTUD and ATUD) are now rated as UL-qualified through-penetration firestop systems. The devices received F (flame) and T (temperature) ratings per ASTM E814 when installed in conjunction with the Simpson Strong-Tie BPRTUD steel bearing plate (RTUD) or the PL steel bearing plate with top plate and nut (ATUD and TUD), eliminating the need for additional fire resistance material at the hole in the plate.
- The Simpson Strong-Tie continuous rod system consists of RTUD and TUD/ATUD take-up devices and bearing plates that provide a full-building-height shrinkage-compensating and tension-force-resisting system.
- To make the system continuous, holes must be drilled through the wall plates and floor sheathing. Reference BPRTUD and PL bearing plate table footnotes for detailed installation instructions.
- These penetrations, if not properly sealed, can be propagation points for flame and smoke during a fire.
- Many building jurisdictions require the application of UL-listed fire caulking to be applied to the penetrations, particularly at locations where rods pass through sill plates and double top plates.
- The new UL rating for the Simpson Strong-Tie continuous rod system provides a tested substitute at these floor penetrations, and when the devices are installed per manufacturers’ specifications, they will attain the F and T ratings shown in the table below.
|RTUD3B||2-hour||1 3/4-hour||Less Than 1 CFM/sq. ft.||ASTM E814|
- RTUDs are to be installed with the Simpson Strong-Tie bearing plate and fastened to the wood plate with
Strong-Drive®SD Connector screws
- TUD/ATUD are to be installed with the appropriate Simpson Strong-Tie bearing plate and secured in place with a heavy hex nut
- No further application of fire caulking or additional procedures needed when drilled through hole is no greater than rod diameter plus 1/4"
- The F rating of the firestop system provided by the take-up device assembly is equal to the hourly fire rating of the floor-ceiling assembly in which it is installed
Advantages of the System
- The take-up device assembly with bearing plates provides UL-listed fire protection for F and T ratings without the need to install costly and time-consuming fire caulking after installation of the take-up device
- The assembly eliminates concerns about traditional fire caulk adhering to the rods and affecting the mechanics of the device, which could restrict rod travel and device functionality
- The assembly has been tested to the same ASTM and UL standards as typical building fire caulk and attains an equivalent fire rating
Description of UL Fire Testing
- Agencies such as the Underwriters Laboratories (UL) define tests and standards to determine an hour rating for how long a building system can adequately resist flame propagation and smoke generation, as well as resist providing additional fuel for combustion.
- Floor-Ceiling Assembly: The one-hour and two-hour assemblies were constructed in a manner and with materials specified in the UL Fire Resistance Directories.
- Flooring System: Lumber or plywood subfloor with finish floor of lumber, plywood or floor-topping mixture as specified in the individual floor-ceiling design.
- Wood Joists: The tested assembly for two-hour fire-rated floor-ceiling assemblies is equivalent to a system with nominal 2x10 lumber joists spaced at 16" o.c. with nominal 1x3 lumber bridging and with ends fireblocked.
- Gypsum Board: Nominal 4' wide by 5/8" thick as specified in the individual floor-ceiling design. Gypsum board secured to wood joists as specified in the individual floor-ceiling design.