Does a penetration have to have even annular space all around or if the detail says minimum is 0in. And max 1/2in, can half of it be 0 and other.half be 1/2in? Or would you want it all to be the same around the penetration?

Greetings Mitch,

Thank you for using ASK Hilti!According to our system UL WL 1304, it allows for an annular space of 0" - 1/2". This means your annular space can fall anywhere within that range. Please note, not all system will allow for continuous point of contact such as WL 1304. In that case, if you cannot find a system that will meet your needs with continuous point of contact, feel free to to submit an engineering judgement request over to us with your specifications.

Hilti is proud to announce the launch of our engineering website, the HILTI CONSTRUCTION PLATFORM (HCP). This platform will be the home for all of your Fire Protection Engineering needs, including Engineering Judgment requests. You can find more information on how to access this new platform here: https://www.hilti.com/ej (US) or https://www.hilti.ca/ej (Canada.)

Along with HCP, Hilti is excited to announce our new mobile app for all your firestop needs: Hilti Firestop Selector. Using the Firestop Selector app gives you easy access to the Hilti Fire Protection Design Team from the jobsite, on the road, or in the office to request a new EJ, an EJ Revision, or ask a Question anytime, anywhere.

If you have any questions, please reach out to our customer service team at 1-800-879-8000 (US) or 1-800-363-4458 (Canada) for assistance.

Thank You for choosing Hilti as your Firestop Experts!

Best Regards,
Austin Griffith
Fire Protection Engineering Team