Multifamily open-ended corridor breezeway rating

[Matt Jones]

I have a client that does multifamily development all over the southeast. We have a project with them that involves several 4-story "breezeway" or open-ended corridors serving the apartments. The construction type is V-A and the project is sprinklered. My reading of code (and that of several other architects I've talked to) is that per V-A, the floor assembly in these breezeways needs to be 1hr rated. The developer is claiming that they've done these in PT wood in multiple states with no issue (and they have...I've seen a few and even have the plans from another architect showing as such), but I don't see a code argument for that being allowed. Am I wrong? Don't want to get on my high horse with the client if there's a loophole (even if I personally don't think there should be). The project is in NC under 2015 IBC. Thanks!

 

[cda]

I will go with 30 minute required rating on the corridor, if it has to meet table 1020.2 due to occupant load.

As far as the floor, Is a one hour horizontal separation required due to the dwellings above and below???

 

[Matt Jones]

I will go with 30 minute required rating on the corridor, if it has to meet table 1020.2 due to occupant load.

As far as the floor, Is a one hour horizontal separation required due to the dwellings above and below???

Yeah, I agree on the corridor separation being min. 30 minute and they have no issue with that.

The floor rating is 1 hour between units and not an issue as well. It's just the corridors I'm concerned about based on the required fire resistance for V-A per Table 601. The exception for sprinklering in lieu of 1hr doesn't apply as R-2 is required to be sprinklered anyway.

 

[RLGA]

Type VA construction requires 1-hour construction for floor/ceiling assemblies; there is no allowance to reduce that fire-resistance rating.

Corridors and egress balconies in Type VA construction do include floor assemblies and must have the 1-hour rating as required for that type of construction.

 

[Matt Jones]

Type VA construction requires 1-hour construction for floor/ceiling assemblies; there is no allowance to reduce that fire-resistance rating.

Corridors and egress balconies in Type VA construction do include floor assemblies and must have the 1-hour rating as required for that type of construction.

That's my belief as well. Just making sure someone else dropped the ball on previous projects and not that I'm missing something.

 

[tmurray]

The wood isn't heavy timber is it? you might be able to get away with a char rating on the wood, provided the minimum size is there to support the structure.

 

[Matt Jones]

The wood isn't heavy timber is it? you might be able to get away with a char rating on the wood, provided the minimum size is there to support the structure.

I did offer that alternative using 3x T&G car decking and HT beams, but that's not what they currently have.

 

[hughdint]

I have a client that does multifamily development all over the southeast. We have a project with them that involves several 4-story "breezeway" or open-ended corridors serving the apartments. The construction type is V-A and the project is sprinklered. My reading of code (and that of several other architects I've talked to) is that per V-A, the floor assembly in these breezeways needs to be 1hr rated. The developer is claiming that they've done these in PT wood in multiple states with no issue (and they have...I've seen a few and even have the plans from another architect showing as such), but I don't see a code argument for that being allowed. Am I wrong? Don't want to get on my high horse with the client if there's a loophole (even if I personally don't think there should be). The project is in NC under 2015 IBC. Thanks!

I have a similar issue but with type VB construction also in NC. A code official says it has to be 1/2 hour rated as it is a "corridor" (Table 1020.1). Client has been building these with PT wood for years as well. Does this apply for corridor-to-corridor floor/ceilings?

 

[Matt Jones]

I have a similar issue but with type VB construction also in NC. A code official says it has to be 1/2 hour rated as it is a "corridor" (Table 1020.1). Client has been building these with PT wood for years as well. Does this apply for corridor-to-corridor floor/ceilings?

That would just be the typical corridor wall separation per Table 1020.1 (assuming your occ. load is greater than 10). Type VB is fine with PT deck corridors. The issue with VA comes out of Table 601. Corridor separation is mandatory for all multifamily, but it's only the walls (and they are rated partitions not barriers, although Mecklenburg county may try to force you otherwise).

 

[hughdint]

Yeah, Meclenburg is tough. Fortunately, my project is in Hickory, but I have a tough FM.
The problem is that table 1020.1 does not specify "wall separation" just corridor rating. It refers to a separate section for wall separation that then refers back to the table. Table 601 footnote "d" says "Not less than the fire-resistance rating required by other sections of this code." So I am back to a 1/2 hour rating for the breezeway floors. The client uses 5/4 PT decking and PT framing that is open below like a deck.

 

[Matt Jones]

Yeah, Meclenburg is tough. Fortunately, my project is in Hickory, but I have a tough FM.
The problem is that table 1020.1 does not specify "wall separation" just corridor rating. It refers to a separate section for wall separation that then refers back to the table. Table 601 footnote "d" says "Not less than the fire-resistance rating required by other sections of this code." So I am back to a 1/2 hour rating for the breezeway floors. The client uses 5/4 PT decking and PT framing that is open below like a deck.

"Corridors shall be fire-resistance rated in accordance with Table 1020.1. The corridor walls required to be fire-resistance rated shall comply with Section 708 for fire partitions."

1020.1 specifically says walls. 708 further reinforces the separation applies to walls. Because of the open framing of the corridors, you would likely need to detail the separation wall GWB to go all the way to the subfloor on the corridor side and then install the ledger over that barrier layer.

 

[RLGA]

When you use "PT," are you referring to preservative-treated wood or fire-retardant-treated wood? "PT" could mean pressure-treated wood, which could be either of those treatments, even though it is usually used to refer to the former. However, the difference is very relevant here. You might be able to convince a code official that the fire-retardant-treated (FRT) wood provides a 30-minute rating; however, I have not seen any documentation to support this. If a layer of 5/8-inch exterior gypsum board or 1/2-inch Type X gypsum board is applied over the FRT wood, I would expect that to be readily acceptable.

"Corridors shall be fire-resistance rated in accordance with Table 1020.1. The corridor walls required to be fire-resistance rated shall comply with Section 708 for fire partitions."

1020.1 specifically says walls. 708 further reinforces the separation applies to walls. Because of the open framing of the corridors, you would likely need to detail the separation wall GWB to go all the way to the subfloor on the corridor side and then install the ledger over that barrier layer.

The reason for pointing out the walls only is to specify which type of wall is required since there is more than one type. Floor/ceiling assemblies are always horizontal assemblies, so there is no need to be specific.

 

[Matt Jones]

I would argue that corridors are also not required to be separated from other corridors. If you have a dwelling unit over a corridor, that's obviously different, but stacked corridors as is typical in multifamily should not need to be rated. The intent is to separate combined egress paths (corridors) from likely sources of fire (dwelling units).

 

[RLGA]

I would argue that corridors are also not required to be separated from other corridors. If you have a dwelling unit over a corridor, that's obviously different, but stacked corridors as is typical in multifamily should not need to be rated. The intent is to separate combined egress paths (corridors) from likely sources of fire (dwelling units).

Read the continuity requirements for fire partitions in Section 708. That would be true if the fire partition extends all the way to the deck and not to the underside of the joists. I have not seen many projects where walls are taken all the way up to the deck.

 

[Matt Jones]

Read the continuity requirements for fire partitions in Section 708. That would be true if the fire partition extends all the way to the deck and not to the underside of the joists. I have not seen many projects where walls are taken all the way up to the deck.

Agreed. Hence why I said this in the previous post:

Because of the open framing of the corridors, you would likely need to detail the separation wall GWB to go all the way to the subfloor on the corridor side and then install the ledger over that barrier layer.

This is very common in garden-style multifamily. So much so that we have a set of typical details we use for this condition.

 

[hughdint]

"Corridors shall be fire-resistance rated in accordance with Table 1020.1. The corridor walls required to be fire-resistance rated shall comply with Section 708 for fire partitions."

1020.1 specifically says walls. 708 further reinforces the separation applies to walls. Because of the open framing of the corridors, you would likely need to detail the separation wall GWB to go all the way to the subfloor on the corridor side and then install the ledger over that barrier layer.

Look at the footnotes for

Agreed. Hence why I said this in the previous post:

This is very common in garden-style multifamily. So much so that we have a set of typical details we use for this condition.

I have continuity of the breezeway walls to the rated roof/ceiling. Including at the floor cavity and ledgers etc.

 

[hughdint]

"Corridors shall be fire-resistance rated in accordance with Table 1020.1. The corridor walls required to be fire-resistance rated shall comply with Section 708 for fire partitions."

1020.1 specifically says walls. 708 further reinforces the separation applies to walls. Because of the open framing of the corridors, you would likely need to detail the separation wall GWB to go all the way to the subfloor on the corridor side and then install the ledger over that barrier layer.

I do not read it that way. Table 1020.1 mentions to see 708 for walls which then refers back to table 1020.1 but footnotes on Table 1020.1 indicate that this rating does apply to floor/ceilings. See footnote "f" for example (specifically the last sentence "Exit access corridors are not required to be rated on any single tenant floor or in any single tenant space, if 1-hour fire-resistance-rated floor/ceiling assemblies are provided in multistory buildings and fire partitions are provided between other tenant spaces on the same floor. The structure supporting such floor/ceiling assemblies and fire partitions is not required to be rated in Types IIB, IIIB and VB construction." this seems to indicate that although the supporting structure does not need to be rated the floor/ceiling of the corridor itself does need to be rated.
I have also used the light framing method with some clients for years but am open to the idea that this may no longer be allowed.

 

[hughdint]

When you use "PT," are you referring to preservative-treated wood or fire-retardant-treated wood? "PT" could mean pressure-treated wood, which could be either of those treatments, even though it is usually used to refer to the former. However, the difference is very relevant here. You might be able to convince a code official that the fire-retardant-treated (FRT) wood provides a 30-minute rating; however, I have not seen any documentation to support this. If a layer of 5/8-inch exterior gypsum board or 1/2-inch Type X gypsum board is applied over the FRT wood, I would expect that to be readily acceptable.

The reason for pointing out the walls only is to specify which type of wall is required since there is more than one type. Floor/ceiling assemblies are always horizontal assemblies, so there is no need to be specific.

The PT is the pressure treated framing and the 5/4 decking. I would just add type X to the underside and call it a day but the 5/4 is put in like a deck with small gaps between them. It would need to be an impervious surface like plywood and lightweight. With those I could get a calculated FR rating of 30 minutes. but the client is resistant to doing "something different" (out of budget).

 

[Yikes]

The structure supporting such floor/ceiling assemblies and fire partitions is not required to be rated in Types IIB, IIIB and VB construction." this seems to indicate that although the supporting structure does not need to be rated the floor/ceiling of the corridor itself does need to be rated.

Of course, since the original poster specified that this was a type V-A building, then per table 601, we're already talking about 1 hour floor construction anyway.

It's the old distinction between fire protection of the floor itself vs fire and smoke separation between the floors.
For example, the OP did not mention # of stories. Any two adjacent stories are allowed to have their corridors atmospherically interconnect with each other, but in V-A the floor construction itself must still be protected with a 1-hour rating. To put it more morbidly, if you were on the upper floor corridor in that scenario, the smoke from the corridor below is allowed to drift up to you and knock you out immediately; but the firefighters get another 60 minutes to come up and drag out your body before the corridor floor collapses in flames.

 

[hughdint]

Of course, since the original poster specified that this was a type V-A building, then per table 601, we're already talking about 1 hour floor construction anyway.

It's the old distinction between fire protection of the floor itself vs fire and smoke separation between the floors.
For example, the OP did not mention # of stories. Any two adjacent stories are allowed to have their corridors atmospherically interconnect with each other, but in V-A the floor construction itself must still be protected with a 1-hour rating. To put it more morbidly, if you were on the upper floor corridor in that scenario, the smoke from the corridor below is allowed to drift up to you and knock you out immediately; but the firefighters get another 60 minutes to come up and drag out your body before the corridor floor collapses in flames.

I had a related question about 3-story VB construction, typical garden-style apartments with four units per floor per breezeway. The breezeway is an open ended corridor with stairs at each end like the OP.
I can understand the logic, just trying to see if there is a definitive code answer as to whether the floor of a breezeway would need to be 30 min rated or not. The code official's logic seems solid but is contrary to my experience, but I cannot justify a non-rating of the corridor floor based on the code citations that I have indicated above.

 

[cda]

I had a related question about 3-story VB construction, typical garden-style apartments with four units per floor per breezeway. The breezeway is an open ended corridor with stairs at each end like the OP.
I can understand the logic, just trying to see if there is a definitive code answer as to whether the floor of a breezeway would need to be 30 min rated or not. The code official's logic seems solid but is contrary to my experience, but I cannot justify a non-rating of the corridor floor based on the code citations that I have indicated above.

So what floor material were you going to specify???

 

[hughdint]

So what floor material were you going to specify???

As per my posts above the client has previously used 5/4x6 PT decking with PT 2x framing that is open below, like standard residential deck construction. The code official cited the Corridor Table 1020.1 and I cannot find a CODE reason why he is wrong other than plenty of folks saying "this is very common" or "we do this all of the time". If I must force the change to a 30 minute rated floor/ceiling at the breezeway, I will, but this will piss off the client and my boss (the AOR) who has tasked me with getting this through.

 

[Mr. Inspector]

OPEN-ENDED CORRIDOR. An interior corridor that is
open on each end and connects to an exterior stairway or
ramp at each end with no intervening doors or separation
from the corridor.

Confused. I can't find any requirements for "open-ended corridors" in section 1020, only for "corridors". What I'm I not seeing?

CORRIDOR. An enclosed exit access component that
defines and provides a path of egress travel.

 

[hughdint]

OPEN-ENDED CORRIDOR. An interior corridor that is
open on each end and connects to an exterior stairway or
ramp at each end with no intervening doors or separation
from the corridor.

Confused. I can't find any requirements for "open-ended corridors" in section 1020, only for "corridors". What I'm I not seeing?

CORRIDOR. An enclosed exit access component that
defines and provides a path of egress travel.

The definition of OPEN-ENDED CORRIDOR says that it is a CORRIDOR so it has the same requirements.