What modifications can be made to a UL certified assembly?

UL certified assemblies are intended to be constructed as shown in individual designs. If a construction element is identified as ‘optional’ or ‘may be provided’ it is not mandatory and doesn’t need to be included in the construction. Also, if a design specification is indicated as a minimum or maximum, the construction can include greater or lesser thicknesses or dimensions respectfully. Additional variances for designs are included in the BXUV Guide Information for Fire-resistance Ratings. Modifications not covered above may be evaluated using an engineering judgment.