Beams going through protected stairways, rating requirements

[blugosi]

I have a type IA high rise where some beams cross through the protected stairways.
Since there are no combustibles in the stairways, do the beams still need to be fire rated?

 

[steveray]

Everything in IA is rated.....

 

[redeyedfly]

Everything in IA is rated.....

Not the stair framing inside the shaft.

 

[redeyedfly]

I have a type IA high rise where some beams cross through the protected stairways.
Since there are no combustibles in the stairways, do the beams still need to be fire rated?

They shouldn't be passing through the shaft. Is this in design or built?

 

[blugosi]

They shouldn't be passing through the shaft. Is this in design or built?

This is design.
Why shouldn't they ?

 

[blugosi]

Everything in IA is rated.....

Right!

Column and beams rating is achieved many ways.
Encasement is one way to do it, so in principle the part of a beam inside a protected stairwell is protected itself.

Throwing a layer of intumescent paint on a beam at the factory is no big deal, but doing it on site raises some issues. The rest of the beams , outside the stairwell I mean, are either encased in plaster boards or treated with intumescent paint on site.

 

[Yankee Chronicler]

Right!

Column and beams rating is achieved many ways.
Encasement is one way to do it, so in principle the part of a beam inside a protected stairwell is protected itself.

Throwing a layer of intumescent paint on a beam at the factory is no big deal, but doing it on site raises some issues. The rest of the beams , outside the stairwell I mean, are either encased in plaster boards or treated with intumescent paint on site.

No.

Where structural members require a fire-resistance rating, they have to be protected with a U.L. (or other agency) assembly that is designed and tested as beam or column protection. Stair enclosures are fire barriers -- they are tested as fire barriers (walls), not as structural member encasement/protection.

Beyond that, you wrote that these beams pass "through" the stairways. That means the beams penetrate the stair enclosure walls.



Depending on what these beams support, they may not be allowed to penetrate the stair enclosure at all. See exception #7.

 

[Yankee Chronicler]

Throwing a layer of intumescent paint on a beam at the factory is no big deal, but doing it on site raises some issues. The rest of the beams , outside the stairwell I mean, are either encased in plaster boards or treated with intumescent paint on site.

This may not be a big deal in Greece, but it's a very big deal in the U.S. Steel fabrication shops are only set up to apply shop primer. Is the project subject to special inspections for fireproofing? If so, you (or the contractor) would have to first find a shop that's even willing to shop apply intumescent paint, then you would have to pay a special inspector to travel to the shop to watch the intumescent coating being applied, and then you would have to ensure that the coating isn't damaged during shipping and installation.

Good luck with that. Here in the U.S. it's a struggle just to get a decent coat of shop primer on structural steel.

 

[steveray]

Not the stair framing inside the shaft.

Not the toilet partitions either, but this is a beam...

 

[redeyedfly]

Throwing a layer of intumescent paint on a beam at the factory is no big deal, but doing it on site raises some issues.

The cost of intumescent paint is that it takes 10 layers and you have to wait between coats. The paint costs the same as wall paint, its the multiple layers that adds all the expense.