Fireproofing Loose Lintel

[bookowski]

I'm referring to 'loose lintels' here, i.e. single angles that span over a window to support a single wythe of brick veneer and bear on the adjacent brick masonry at each end. My code states that these must be fireproofed for 'openings wider than 4 feet'. Any experience with this? It doesn't even say 'span more than 4 ft' in which case you could add intermediate hangers thereby reducing the span. Are people fireproofing loose lintels over a 5ft window? Particular case I'm looking at is metal stud backup to the brick veneer on a conc bldg. Code excerpt below:

704.11 Lintel protection:
Lintels over openings wider than 4 feet (1219 mm) in masonry walls, other than in walls of masonry veneer on wood frame structures, shall be fire protected as required by Section 704.3 when the full load over the opening is not relieved by a masonry arch of required strength.
Exceptions:1.The members of an assembled metal lintel that support only outer face masonry that is securely bonded or anchored to backing need not be fire protected, provided that the inner members of the assembly support the full load imposed.

 

[XR250]

How on earth do you fireproof a loose lintel? Sounds like if you make your metal studs load bearing, you can use them to support the lintel and be exempt

 

[KootK]

Yeah, how to fireproof a loose lintel boggles my mind too. I can't imagine that intumescent paint would be a popular choice.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[dik]

I've used intumescent coatings where FRR is required.

Dik

 

[jike]

Two options:

1) Intumescent paint to meet required rating
2) Use masonry or concrete lintel with appropriate cover to meet required rating.

 

[jike]

Another option may be to cover the lintel with fire rated gyp board, if it works with the architecture.

 

[JAE]

What code is this? The IBC 2012 suggests a 6'-4" max. span for lintels without fire protection but if the lintels are not part of the structural frame they don't need anything.

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[KootK]

I think it's NYC code. See p.145: Link

Based on the provisions quoted, and the stone lintel provision that follows that, my read on intent is this:

1) The thing that does the primary spanning across the opening should be fireproofed.

2) Ancillary stuff attached to #1 does not need to be fire proofed.

Given that:

1) It seems likely that a loose lintel would need fireproofing.

2) I really think that a lintel hung at 4' intervals would satisfy intent.

As you know, I don't practice in NY so I can't supply any boots on the ground advice beyond that.

when the full load over the opening is not relieved by a masonry arch of required strength.

It's reaching but I wonder if this could be extended to mean:

1) A lintel that can one side or two side arch with only a wedge of brick being supported by the angle.

OR, even more aggressive:

2) A lintel with CJ each side where the supported brick would span as a flexural member to the far ends of the lintel, with the lintel essentially just transferring shear to the supporting brick.

Even if those things are possible, it's probably more trouble than it's worth to try and procure approval for them.


I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[bookowski]

Correct to NYC code. IBC says not required on "bottom flange of lintels" that are not part of structural frame - what does this mean? You fireproof the vertical leg but not the outstanding?

I agree that hangers at 4ft would probably placate someone reviewing it.... but on a large job this could be hundreds of hangers from the slab. The contractor here has asked about screwing the lintels to the backup stud header which I nixed and set off this conversation. So far everyone I've asked locally has said that they just ignore this and no one does it. In nyc there is no real review - you could use a piece of spaghetti as a lintel if you sign off on it.

 

[XR250]

I worked on a light gage job where the EOR had L6x6 lintels (5'-4" long) attached to the backup cold-formed framing but no bearing at either end on the brick.
I did not catch that because who in their right mind would design something like that. I never designed the framing to carry that load. As such, they ended up having 40 all new lintels fabricated 12" longer so they could truly be loose and bear on the brick. Fortunately, the light gage contractor helped me out on everything but $500 as I argued the additional cost of the framing and labor to have actually built it the original way would have been significant.