We have a project under construction in Maryland, per DFM comments we need to protect the lobby stair stringers and stair landing steel with a 2-hour rating. The stair stringers and landing steel were originally designed to be AESS level 4 finish with a PPG White Ice Metallic UC106706XL topcoat. We're looking for an intumescent coating with a smooth finish.
Most (it seems like all) intumescent coatings have an "orange peel" or otherwise textured finish. Hilti's Fire Finish 120+ CFP-SP WB cutsheets states the following: "Glass fiber free product leads to better applied aesthetics." Will this intumescent paint have a smooth(er) finish? Is it possible to still achieve AESS 4? Can we paint over the intumescent coating with the PPG paint mentioned above?
Hello I have attached the approved Primer and Top coat for FF120+. The PPG UC106706XL does not appear to be on either of the lists unfortunately (it would need to be on the primer for us to spray over it). If you reach out to PPG and they have have one of the approved primers that is compatible with the UC106706XL then you can spray that primer over the top coat, and then follow the IFU on how to spray after. Else the other option is to remove the material already installed to bare steel and follow the IFU on how to prep the steel, primer, FF120+ then optional Top Coat if desired. I have also provided the calculation on how to provide WFT / DFT mils on our excel sheet, we typically treat stair stringers like American C-Channels for mil thickness.
Thank you,
Chase Hellan
Sr. Fire Protection Engineer
