Painting exterior steel not exposed to weather - is paint required

[cliff234]

We are designing structure (apartment building) that has on-grade parking, a steel-framed floor above the parking level and several floors of wood-framed residential construction above. The steel framing is in the ceiling of the parking level. The parking level is open on all sides and unheated. The steel will will be spray-fireproofed. Does the steel need to be painted? Will the spray fireproofing provide any protection to the steel? We would like to avoid painting the steel if possible. Thanks for any insight anyone can share.

 

[TonyDeRamo]

Unpainted. "Paint may weaken the adhesion of spray-fireproofing".

At least that is what I have gathered from a simple Google search.

I'm not sure how clean the surface needs to be, but I would think you do not want any rust, grease or oil.

"Research is what I'm doing when I don't know what I'm doing."

 

[dcarr82775]

You do not paint steel that is to have sprayed on fireproofing applied. Without looking into it I do not know if you can leave fireproofing exposed to the elements.

 

[Robbiee]

Fireproofing spray doesn't provide corrosion protection. In fact it can help corrosion by absorbing moisture and keeping it. Some primers are pretested for bonding with fire spray. You can check with UL and specify that type of paint. Otherwise, you need to ask for bond tests to satisfy the code requirements. If bond is not achieved, you might need to achieving it mechanically. I echo the concern of leaving the fire spray exposed.