We are designing a multifamily, 4 stories, primarily wood framed structure (Type VA Construction). A portion of the second floor will require steel framing since the first floor spaces are Community type spaces. We were planning to protect those steel members with an intumescent coating, but inherently we need to attach nailers, studs, etc. in order to frame out spaces. Is it ok to install wood framing and nailers directly to steel members that have been coated with the intumescent paint? See attached for some details.
Good morning Jamie,
Thank you for using ASK Hilti!
IBC actually has a statement about how to treat secondary members as the following "704.6.1 Secondary attachment to structural members. Where primary and secondary structural members require fire protection, secondary tubular steel attachments to those structural members shall be protected with the same fire-resistive material and thickness as required for the structural member. The protection shall extend away from the structural member to encompass at a distance not less than 12 inches. If the secondary attachment is less than 12 inches, then the intumescent fire resistive material shall be applied to the entire length of the attachment." However, with your wood members we would need to look more into the specifics of your application. Please feel free to submit an for an engineering judgement request through www.hilti.com/EJ and we would be happy to take a deeper look into that for you.
If you have any questions firestop related, please reach out to our customer service team at 1-800-879-8000 (US) or 1-800-363-4458 (Canada) and ask to speak to the firestop team for assistance. We would be happy to walk you through the details of any firestopping Hilti UL/cUL listed systems you needed.
Best regards,
Austin Griffith
Fire Protection Engineering team