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Replacing Exterior Wall on a 6 Story Building

Dominic

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Jun 20, 2017
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43
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Albany
I am currently working on a rehab of a 6 story residential (R-2) apartment building that was constructed around 1964-65. The exterior brick veneer has failed due to numerous reasons of poor workmanship and lack of expansion joints. Behind the brick is 4” cmu and plaster. The owner wants to replace the entire exterior wall assembly with metal studs and exterior finish panel.

My question is back when this was built the primary framing was not required to be rated. The floor and ceiling assembly is noted on the drawings to have a 3 hr. rated assembly. See attachment. In the renovation a full NFPA 13 sprinkler system will be installed. The scope of work will put the project to Level 3 Alterations. I reviewed the Existing Building Code and what I am reading is that replacement should not decrease the level of safety. The exterior wall does have some rating but stops at the beam.

Here is my code interpretation based on building a new building base on NY 2020 Building Code. I classified the building as 1B because the building exceeds the allowable number of stories of 2B.

Primary and Secondary Steel – 2 Hrs.
Exterior Wall >30’ – 0 hours.

What would be the proper way to address this? Because there is no rating now is it acceptable to leave it? Does the new wall need to be similar rating and stop at the underside of the beam? Do I fire rate the beam with a ul listed gypsum enclosure that extends to the rated ceiling assembly?
 

Attachments

  • Exterior Wall Detail.pdf
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mtlogcabin

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Big Sky Country
Because there is no rating now is it acceptable to leave it?
Yes I think so based on the following. Even though you do not have a change of occupancy this section should logically apply to a repair
2018 IEBC
1011.6.2 Exterior wall rating for change of occupancy classification to an equal or lesser-hazard category.
Where a change of occupancy classification is made to an equal or lesser-hazard category as shown in Table 1011.6, existing exterior walls, including openings, shall be accepted.
 

Dominic

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Jun 20, 2017
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Albany
Yes I think so based on the following. Even though you do not have a change of occupancy this section should logically apply to a repair
2018 IEBC
1011.6.2 Exterior wall rating for change of occupancy classification to an equal or lesser-hazard category.
Where a change of occupancy classification is made to an equal or lesser-hazard category as shown in Table 1011.6, existing exterior walls, including openings, shall be accepted.
Thank you for your response. I did not think about looking at it this way but your logic makes sense.
 

RLGA

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Phoenix, AZ
The floor and ceiling assembly is noted on the drawings to have a 3 hr. rated assembly. See attachment.
How do you figure that it is a 3-hour rated floor assembly? The detail indicates it is 3 inches of concrete on a metal deck.

In order to get a 3-hour rating, the concrete would need to be at least 4.4 inches (at its thinnest location) using lightweight concrete. If using standard concrete, the thickness would need to be somewhere between 5.7 and 6.6 inches.

The most it could be is 1-hour, and if they used composite decking, then it would have no rating if the deck was not protected by fireproofing.

What is the recorded construction type of the building at the time it was built? Under the IBC, the construction type would need to be Type IB, which allows unlimited area and 12 stories for Group R-2.

Regarding the application of the IEBC, I would forgo using the work area compliance method and use the prescriptive compliance method per Section 503. The prescriptive compliance method is mostly focused on structural matters, and Section 503.1 allows you almost great latitude working with the new construction, provided that you do not make the building less compliant than it was prior to the alteration. Of course, all new construction must comply with the current code.

As for the exterior walls, non-combustible materials would definitely be required. The building does not comply with Type IIB or IIA for height (not sure where the building is area-wise since you did not provide that information), nor does it appear to comply with Type IB construction, which requires 2-hour floor construction and 2-hour construction for most other building elements. Thus, I would consider the building Type IIA (1-hour construction throughout) for all other code matters, which means you cannot add stories or increase the floor area since that would make the building less compliant than it was prior to the alteration.

Using Type IIA construction, 1-hour exterior walls would be required if the fire separation distance was less than 30 feet. If the fire separation distance is greater than 10 feet, then the walls need only have the rating for an interior exposure.
 

Dominic

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Jun 20, 2017
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Albany
How do you figure that it is a 3-hour rated floor assembly? The detail indicates it is 3 inches of concrete on a metal deck.

In order to get a 3-hour rating, the concrete would need to be at least 4.4 inches (at its thinnest location) using lightweight concrete. If using standard concrete, the thickness would need to be somewhere between 5.7 and 6.6 inches.

The most it could be is 1-hour, and if they used composite decking, then it would have no rating if the deck was not protected by fireproofing.

What is the recorded construction type of the building at the time it was built? Under the IBC, the construction type would need to be Type IB, which allows unlimited area and 12 stories for Group R-2.

Regarding the application of the IEBC, I would forgo using the work area compliance method and use the prescriptive compliance method per Section 503. The prescriptive compliance method is mostly focused on structural matters, and Section 503.1 allows you almost great latitude working with the new construction, provided that you do not make the building less compliant than it was prior to the alteration. Of course, all new construction must comply with the current code.

As for the exterior walls, non-combustible materials would definitely be required. The building does not comply with Type IIB or IIA for height (not sure where the building is area-wise since you did not provide that information), nor does it appear to comply with Type IB construction, which requires 2-hour floor construction and 2-hour construction for most other building elements. Thus, I would consider the building Type IIA (1-hour construction throughout) for all other code matters, which means you cannot add stories or increase the floor area since that would make the building less compliant than it was prior to the alteration.

Using Type IIA construction, 1-hour exterior walls would be required if the fire separation distance was less than 30 feet. If the fire separation distance is greater than 10 feet, then the walls need only have the rating for an interior exposure.
Thank you for you in depth review and response.

The building was constructed around 1965 under the Code Manual for the (New York) State Building Construction Code.

The building is 8600 s.f. per floor. Reading 1959 Code the only classification that works would be Type 1 construction. Not sure if this is relevant since the maximum Ceiling/Floor UL assembly is one hour.

Based on this it would lead me to an existing non-conforming Type IIA construction. Non-conforming would be the height of the building exceeds the allowable 5-stories. Then I base the building code review on Type IIA construction? I would not be adding height or area to less code compliant.
 
Last edited:

RLGA

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I assumed Type IIA because I thought you exceeded both height and area. At 8,600 sq. ft. per story, that would be a total of 51,600 sq. ft. of building area. Type IIB construction allows 48,000 sq. ft. per story (up to three stories), for a total of 144,000 sq. ft. of allowable building area. So, with Type IIB construction, the only existing condition that is non-compliant with the current code is the height in stories (I assume the height in feet is less than 75 feet).

This actually helps, since I noticed the huge steel beam in the detail did not indicate any fireproofing. With Type IIB construction, no fire-resistance-rated construction is required, and the exterior walls need only be 1-hour rated if the fire separation distance is less than 10 feet.

If the building department pushes back on this classification, you could probably justify your position by stating that even though the building height exceeds the current allowable height in stories by one story, the allowable area is less than 36% of the allowable area for this building type.

If the refuse to accept this construction type classification, then offer IIA as a compromise. It is still over height by one story, but the building area will be less than 24% of that allowed and less than 85 feet in height. However, you would need to apply fireproofing to all structural steel framing and secondary members (and metal deck if composite deck). Exterior wall construction would need to be as I described in my previous post.
 

Dominic

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One last question. If IIA Construction does the primary steel beams and secondary framing need to be fireproofed if its within the fire rated floor/celing assembly (UL G241)? I understand the columns would still need to be rated.
 

RLGA

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The beams and girders would be required to have individual protection, but the secondary members as part of a floor/ceiling assembly would only need to be protected if the assembly required it.

UL G241; however, appears to be different than your condition in respect to the concrete portion. The assembly does not indicate a metal deck, just metal pans specifically manufactured by Roxul. A system similar to this one that matches your exact existing construction would be acceptable.
 

Dominic

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Albany
The beams and girders would be required to have individual protection, but the secondary members as part of a floor/ceiling assembly would only need to be protected if the assembly required it.

UL G241; however, appears to be different than your condition in respect to the concrete portion. The assembly does not indicate a metal deck, just metal pans specifically manufactured by Roxul. A system similar to this one that matches your exact existing construction would be acceptable.
Thanks for all your help!
 

Dominic

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Agreed. This is an option. The code states "repairs may be made using materaials and methods like those of the original construciton or the extent to which repairs must comply with requirements for new buildings". In this case we are replacing the enterior exterior.
 

Dominic

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Albany
The beams and girders would be required to have individual protection, but the secondary members as part of a floor/ceiling assembly would only need to be protected if the assembly required it.

UL G241; however, appears to be different than your condition in respect to the concrete portion. The assembly does not indicate a metal deck, just metal pans specifically manufactured by Roxul. A system similar to this one that matches your exact existing construction would be acceptable.
Again thank you for all your help. I have one more question.

Where in the code does it define how to terminate a horizontal fire-rated to the exterior wall? The floor/ceiling assembly has 1 hour and the exterior wall is not rated. I read through 711 and it does not address it.
 

Dominic

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Why is the horizontal assembly rated? Is it a fire barrier?
I am looking at classifying the building as 2A. I also need it for tenant seperation.

Its not a fire barrier. Its a horizontal fire rated assembly. Section 711 - Floor and Roof Assemblies.
 

steveray

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So an R2 separation that is allowed to be 30 min. in a sprinklered building?

711.2.4.3 Dwelling units and sleeping units. Horizontal
assemblies serving as dwelling or sleeping unit separations
in accordance with Section 420.3 shall be not
less than 1-hour fire-resistance-rated construction.
Exception: Horizontal assemblies separating dwelling
units and sleeping units shall be not less than 1/2-
hour fire-resistance-rated construction in a building
of Type IIB, IIIB and VB construction, where the
building is equipped throughout with an automatic
sprinkler system in accordance with Section
903.3.1.1.
 

steveray

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So this?

712.1.5.1 Joints in or between horizontal assemblies.
Joints made in or between horizontal assemblies shall
comply with Section 715. The void created at the intersection
of a floor/ceiling assembly and an exterior curtain
wall assembly shall be permitted where protected
in accordance with Section 715.4.

715.4 Exterior curtain wall/floor intersection.Where fire
resistance-rated floor or floor/ceiling assemblies are required,
voids created at the intersection of the exterior curtain wall
assemblies and such floor assemblies shall be sealed with an
approved system to prevent the interior spread of fire. Such
systems shall be securely installed and tested in accordance
with ASTM E2307 to provide an F rating for a time period
not less than the fire-resistance rating of the floor assembly.
Height and fire-resistance requirements for curtain wall spandrels
shall comply with Section 705.8.5.
 

Dominic

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Jun 20, 2017
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Albany
A
So an R2 separation that is allowed to be 30 min. in a sprinklered building?

711.2.4.3 Dwelling units and sleeping units. Horizontal
assemblies serving as dwelling or sleeping unit separations
in accordance with Section 420.3 shall be not
less than 1-hour fire-resistance-rated construction.
Exception: Horizontal assemblies separating dwelling
units and sleeping units shall be not less than 1/2-
hour fire-resistance-rated construction in a building
of Type IIB, IIIB and VB construction, where the
building is equipped throughout with an automatic
sprinkler system in accordance with Section
903.3.1.1

So this?

712.1.5.1 Joints in or between horizontal assemblies.
Joints made in or between horizontal assemblies shall
comply with Section 715. The void created at the intersection
of a floor/ceiling assembly and an exterior curtain
wall assembly shall be permitted where protected
in accordance with Section 715.4.

715.4 Exterior curtain wall/floor intersection.Where fire
resistance-rated floor or floor/ceiling assemblies are required,
voids created at the intersection of the exterior curtain wall
assemblies and such floor assemblies shall be sealed with an
approved system to prevent the interior spread of fire. Such
systems shall be securely installed and tested in accordance
with ASTM E2307 to provide an F rating for a time period
not less than the fire-resistance rating of the floor assembly.
Height and fire-resistance requirements for curtain wall spandrels
shall comply with Section 705.8.5.
The exerior wall is not a curtain wall.
 
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