Head of Wall (HOW) - Overview UL Letter

UL Letter


On February 5, 2008, Underwriters Laboratories, Inc.(UL) issued a letter that explains the results of the HOW fire tests performed for MBMA the previous summer. This letter indicates that the UL listings, HW-D-0488, HW-D-0489, and HW-D-0490, could only be issued with fire-rated walls and fire-rated roof-ceiling designs, as specified by the ANSI/UL 2079 standard. However, this letter states the assemblies that were actually tested consisted of an unrated roof-ceiling assembly and a rated wall. The performance in the tests did meet all the referenced acceptance criteria and could be applied “to those P200 and P500 Series Roof-Ceiling Designs in the Fire Resistance Directory which specify the use of the basic roof structure.”



To see the complete UL letter as a PDF, please click here.


To view these original UL Head of Wall listings, please click on the appropriate listing below to go to the UL website:





To return to the Head of Wall Overview page, please click here.

To return to the Fire Resistance Overview page, please click here.


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