SFPE Discussions

Structural steel penetrations through Fire walls

What is this forums opinion on treatment of Structural Penetrations through firewalls. Hilti has an engineered solution for using CP606 mastic in the annular gaps between the wall and the steel member provided the steel member is unprotected.

They will not support this solution if the structural steel member has Intumescent paint applied as their system is not tested and they are unsure of how the two intumescent systems would work hence the reason not to support.

Typically we have structural steel painted throughout and then the Fire walls get installed around the structure.

Also what about insulation requirements. Intumescent protected structural members do not provide insulation rating I am told. ASFP recommends applying some sort of protection to 500mm on either side of the fire separation.

Thoughts ?

It sounds like fire sealing of unprotected steel through a fire separation is a waste of time. The unprotected steel generally will compromise your fire separation unless you have taken specific structural precautions in your fire separation - like providing a structurally adequate fixing/penetration point capable of withstanding structural collapse on the fire side of the wall without compromising the fire separation.
That still leaves your issue of fire sealing an intumescent paint protected structural element passing through a fire separation.
Sorry I haven’t got an answer but it appears that Hilti CP606 is not the solution.
Is making your fire separation structurally adequate to “break” the structural element at the fire separation so that the structural element fastens to mounting points (cleats) on each side of the fire separation an option?


Firewall is a firewall or a fire separation.

The key difference is a firewall needs to stand up, even after a building falls down.
The fire separation has to be intact.

So structural steel through fire walls SHOULD NOT BE DONE, PLEASE. Dividing existing buildings up need to have that taken into account. A pier and a column on each side of the firewall would be suggested, unless you created a firewall with beam pockets, such that the required fire separation was maintained between the pockets.

This will deal with the structural issue.

The fire issue of the penetration while it could be done with intumescent or with another approval material such as drywall and than a thin link of caulking or accepting the tight fit, and relying on the intumescent of the beam paint to provide for the gap expansion required.

Hilti is looking for you to pass on the need for more testing for the intumescent to intumescent reaction at elevated temperatures, so that they can research funding perhaps? It’s a point that would need a Master’s student to have a look, and provide a point of view review, if not a group of them from a few universities.

You could test the product and the connection too, yourself for your own self re-assurance.

As for the insulation requirements that depends, since it’s not an exterior wall, what normal thermal transfer are you looking to prevent.
If you are referring to sound insulation, yes the beam will transfer that energy by it’s very nature, disconnect the beam, provides a break in the circuit that allows the transfer of energy and thereby solves that problem. Note it also helps with the thermal transfer, and the structural stability of the wall.

Sorry there are points of confusion, in what you are asking so there is only so much i can provide without some language clarification. Aka firewall or fire-separation, which is a function of which regulations that govern the project.

A good question, whcih is often overlooked

In terms of the thermal penetraiton for the insulation

Onesteel has some info:

and also