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Fire Protection and Steel Beams

plumb_bob | Posted in General Questions on

I am reviewing a renovation and change of occupancy for a small 2 storey mixed use building. It is wood frame construction with the second floor supported on steel I beams. The original construction had no fire separations or fire resistance ratings, the new construction will require the floor and suite separations to have 45 minute fire resistance ratings.
The code I am using (BCBC) has several options for fire protection of individual steel beams, and the proposed method is portland cement-sand on metal lathe that fastened to metal channels held in position by metal wire.
I am unfamiliar with the constructability of this method, has anybody else used this or dealt with this? Would this be a sprayed application or troweled on?

Any feedback would be appreciated. Thanks!

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  1. Expert Member


    The fire protection I've seen used on the exposed steel beams over at-grade parking on condo and mixed use buildings is a cementatious or fiber spray with no mesh or lath. It adheres directly to the steel and quite closely follows it's profile.

    1. plumb_bob | | #2

      Thanks Malcolm. Do you think that product is intumescent?

      1. Expert Member
        MALCOLM TAYLOR | | #4


        I don't know anything about it, beyond that I was surprised to see it in so many exposed locations. It doesn't look great as a finished material.

        1. Patrick_OSullivan | | #5

          And pulling wire or similar activities near it will cause it to rain down in clumps that will go down the back of your shirt so you can realize that it's the itchiest substance known to humans.

          1. Expert Member
            MALCOLM TAYLOR | | #6


            Sounds like you are speaking from experience.

  2. R787 | | #3

    Will your code accept UL rated assemblies? While I find the books easier to use, you can also access their rated assemblies online here: There are probably 100 different ways to get to your end point using typical construction materials and methods, I'd suggest using one that's the most similar to the construction in the rest of your project.

    For small projects at the interior I've most often seen things boxed in Type X gyp board

  3. Expert Member
    BILL WICHERS | | #7

    I've always seen the spray-on coatings Malcolm mentioned. They do dry to a very dusty and crumbly material that rains down on you while working. I usually see the stuff as a light gray material, but I've also seen blue which we call "smurf barf". I've been told this stuff is basically a fire resistant thermal insulation to buy time in a fire before the steel fails. I don't think it's an intumescent coating, but I'm not sure about that.

    All of these coatings are sprayed on with a spray rig a little like is used for spray foam. It's messy to apply, with little bits getting everywhere. Every job I've been on has had the fire retardant crew scheduled so that they are there when NO other trades are on site. They typically spray the coating after electrical rough in is complete (all the conduit and hangers are up), but otherwise fairly early in the construction.


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