1 hr fire rated detail- one side only

[RL-inc]

I have a buddy that is building a steel warehouse and he needs a 1hr fire rated assembly along the rear wall line due to proximity to PL.

Typ. steel building with no sheathing on the exterior side .

He does have 5/8" type X on the interior but I can't find a 1hr detail showing only that material on one side-

Anyone ever see a similar condition of have a supporting detail?

 

Much appreciated as always

[rlackore]

Does the fire separation distance require a wall rated from both sides, or just the interior side?

[RL-inc]

I will look at the drawings when I check the job this afternoon-

If it is required from both sides the building design the had approved would not have met that standard however-

That said, I am assuming that the rating is from the interior side only.

[rlackore]

Check out the UL BXUV V421 assembly. If you don't have access to the online UL database, you can use the attached publication from the MBMA - it's old, but the assembly hasn't changed. The head-of-wall is an area of special concern - you'll have to detail that yourself based on the roof construction.

 

MBMA UL V421.pdf

 

 

[RL-inc]

Thanks Robert-

Looks like the min I can find for a one side only application is 3 layers of 5/8" type X per WP9021.

Better run with what we have spec'd!

[rlackore]

The Gypsum Association WP 9021 requires 3 layers of 5/8" type X, but the UL V421 allows 3 layers of 1/2" regular. The UL assembly might save a bit of money, if the building department allows the UL assembly.