Type V-A construction

[retire09]

To achieve V-A construction in a wood framed structure, all exterior bearing walls and the ceiling are required to be protected by a full 1 hour rating from the inside only to protect the structure inside the walls and above the ceiling? Interior bearing walls would require a full 1-HR rating on both sides (2HR assembly). Is this correct?

We are not looking for 1-HR rated walls or assemblies with half the rating on each side that only provide a 1/2 HR fire resistance protection for the structure. Am I right??

 

[imhotep]

To achieve V-A construction in a wood framed structure, all exterior bearing walls and the ceiling are required to be protected by a full 1 hour rating from the inside only to protect the structure inside the walls and above the ceiling? Interior bearing walls would require a full 1-HR rating on both sides (2HR assembly). Is this correct?We are not looking for 1-HR rated walls or assemblies with half the rating on each side that only provide a 1/2 HR fire resistance protection for the structure. Am I right??

705.5 Fire-resistance ratings. Exterior walls shall be fire-resistance rated in accordance with Tables 601 and 602 and this section. The required fire-resistance rating of exterior walls with a fire separation distance of greater than 10 feet (3048 mm) shall be rated for exposure to fire from the inside. The required fire-resistance rating of exterior walls with a fire separation distance of less than or equal to 10 feet (3048 mm) shall be rated for exposure to fire from both sides.

Exterior bearing walls with fire separation > 10' : 5/8" Type 'X' on 2 x framing at 16" o.c. per IBC section 721. (1 hr)

Interior bearing walls are 1-HR, not 2-HR. 5/8" Type 'X' at ea side of 2 x framing at 16" o.c. per IBC section 721. (1 hr)

 

[mtlogcabin]

We are not looking for 1-HR rated walls or assemblies with half the rating on each side that only provide a 1/2 HR fire resistance protection for the structure. Am I right??

No a one-hour rated assembly is rated one-hour from either side. Unless the assembly is listed with a fireside designation. Exterior wall assemblies may be listed that way such as GA WP 8006 or you may use IBC Table 721.6.2(1) to accomplish it.

2009 IBC TABLE 721.6.2(1)

TIME ASSIGNED TO WALLBOARD MEMBRANESa, b, c, d

d. The membrane on the unexposed side shall not be included in determining the fire resistance of the assembly. When dissimilar membranes are used on a wall assembly, the calculation shall be made from the least fire-resistant (weaker) side.

Gypsum Manual

Where unsymmetrical systems were tested from oneside only, the side exposed to the test fire is indicatedby the words "Fire Side" on the system detail. Whendocumentation is available to show that the wall wastested with the least fire-resistive side exposed to thetest fire, the wall need not be subjected to tests from theopposite side and a "Fire Side" is not specified. All floorceilingand roof-ceiling systems were tested with fire

exposure on the ceiling side.

 

[AegisFPE]

The fire-exposed membrane and framing both contribute to the rating of the assembly.

 

[peach]

I agree with the Pharoah.

 

[imhotep]

The fire-exposed membrane and framing both contribute to the rating of the assembly.

I guess I don't understand 721.6.2

705.5 says > 10 feet - 1-hr shall be rated for exposure to fire from the inside.

TABLE 721.6.2(1) gives 5/8" Type 'X' = 40 minutes

TABLE 721.6.2(2) gives 2 x 4 @ 16" o.c. = 20 minutes

so....

5/8" Type 'X' on the inside of 2 x wall framing calculates at 60 minutes, but...

How does footnote d to TABLE 721.6.2(1) factor in?

d. The membrane on the unexposed side shall not be included in determining the fire resistance of the assembly. When dissimilar membranes are used on a wall assembly, the calculation shall be made from the least fire-resistant (weaker) side.

 

[AegisFPE]

You seem to understand the code, just not my reduction of 721.6.2.1, which was intended to address the OP's question regarding 1-hour protection of the wood structure. The answer is no, because the code states that the wood structure is a sacrificial part of the assembly.

As for Footnote d, it tells me that if I have 1/2-inch gwb on one side and 5/8-inch Type X gwb on the other (thereby non-symmetrical with dissimilar membranes) that I need to assume my fire-exposed side for calculating the rating of my assembly is the 1/2-inch gwb side.

Exterior walls are addressed in 721.6.2.3 (so one could question if the above referenced footnote to 721.6.2.1 was even applicable).

 

[retire09]

I agree with the wall rating per table 601 and 602 but what rating is required on the bottom cord of a wood truss?

 

[imhotep]

You seem to understand the code, just not my reduction of 721.6.2.1, which was intended to address the OP's question regarding 1-hour protection of the wood structure. The answer is no, because the code states that the wood structure is a sacrificial part of the assembly.As for Footnote d, it tells me that if I have 1/2-inch gwb on one side and 5/8-inch Type X gwb on the other (thereby non-symmetrical with dissimilar membranes) that I need to assume my fire-exposed side for calculating the rating of my assembly is the 1/2-inch gwb side.

Exterior walls are addressed in 721.6.2.3 (so one could question if the above referenced footnote to 721.6.2.1 was even applicable).

Ah Ha. I see what footnote d. is driving at. As to the exterior wall a little more digging and...

721.6.2.3 Exterior walls. For an exterior wall with a fire separation distance greater than 5 feet (1524 mm), the wall is assigned a rating dependent on the interior membrane and the framing as described in Tables 721.6.2(1) and 721.6.2(2). The membrane on the outside of the nonfire-exposed side of exterior walls with a fire separation distance greater than 5 feet (1524 mm) may consist of sheathing, sheathing paper and siding as described in Table 721.6.2(3).

 

[Examiner]

I did some looking in the tested assemblies provided by the three manufacturers of gypsum products. I searched only for combustible bearing walls interior and exterior. All that I viewed for an hour fire rating had gypsum on each side of the studs. I did not see any that listed fire ratings from only one side.

I contacted Code Congress and inquire about the Code’s requirement stating, rating from the interior when the rated exterior wall was over 10-ft from the property line. I was told that you do not add another layer of protection to the rated wall. The same comment was also for exterior protection.

That makes sense since not one manufacturer listed a tested assembly for a bearing wall with on only one side being protected.

 

[mtlogcabin]

rating from the interior when the rated exterior wall was over 10-ft from the property line.

The idea is not new to the codes. It was permitted under the SBCCI in the early 90's.

 

[JustReid]

I agree with the wall rating per table 601 and 602 but what rating is required on the bottom cord of a wood truss?

1 hour. An example would be Gypsum Association File No. FC 5408 Generic. Statement at the bottom says," Ceiling provides one hour fire resistance protection for trusses."

 

[gbhammer]

It would not be V-A con. type unless the entirety of all the supporting members are 1-hour rated. Not as easy as it would seem. Home builders have been hit hard here and have been taking on commercial work that they have no business trying to do. Here is an example of comments to a RDP that tried to take on a commercial addition / remodel. I am still waiting for his response.

Owner or the owner’s agent should provide the following.

1. This project may require the submittal of a special inspection program (IBC 1704), which should include:

a. A special inspection schedule.

b. A special inspection testing agreement.

c. An approved special inspection agency (The Jefferson County Building Department can provide a list of approved special inspection agencies).

2. A soil report will be required (This will include but not be limited to a seismic classification for the building site IBC 1704.7 / 1802.2).

3. An approved site plan that indicates the dimensions between all the existing structures, the property lines and the new structure (IBC 106.2).

4. Provide verification, from an engineer or the public sewer district that the sanitary system will be adequate for the additional loads that will be placed upon it.

5. Submit a brief written commentary on the use and contents of each room.

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The registered (Architectural) design professional in charge should provide the following.

1. Provide two complete sets of signed and sealed plans which should not include any phase other than the one under construction.

2. Sheet A001; the code block data should be either revised, or in some instances revaluated:

a. 2002 NEC.

b. Mixed Use Group / Separated S-1, B

i. Fire separation requirement = 3 hour (IBC T302.3.2).

1. If the building meets the requirements for 5A construction, then a non-separated mixed use group could be used (IBC 302.3.1).

c. Construction Type 5A; (IBC T601 & T602)

i. Fire resistance rating for all structural elements = 1 hour.

1. The plans do not accurately depict a 1 hour rating at each required location.

ii. Fire resistance rating for east wall within 5’ of a lot line = 2 hour.

d. Allowable Tabular Building Area (IBC T503)

i. VB construction type = B use 9,000 sq. ft. / S1 use 9,000 sq. ft.

ii. VA construction type = B use 18,000 sq. ft. / S1 use 14,000 sq. ft.

e. Allowable Building Height (IBC T503)

i. VB construction type = B use 2 story / S1 use 1 story

1. The building as currently depicted in the plans would retain a VB construction type and would therefore require either three hour separation or a sprinkler system in order to meet the Building height limitations.

ii. VA construction type = B use 3 story / S1 use 3 story

f. Occupant Loads First Floor (IBC T1004.1.2) Total = 29

i. Garage area = 21 occupants – 4,200 sq. ft. @ 200 per.

ii. Office area = 8 occupants – 780 sq. ft. @ 100 per.

g. Occupant Loads Second Floor (IBC T1004.1.2) Total = 93

i. Conference room = 80 occupants – 1,200 sq. ft. @ 15 per.

1. Unconcentrated (tables and chairs)

ii. Exercise room = 6 – 280 sq. ft. @ 50 per.

iii. Office areas = 7 – 700 sq. ft. @ 100 per.

h. Minimum Number of Exits = 2 @ 1-500 occupants (IBC T1018.1)

i. First floor 1 exit required 4 provided

1. IBC T1018.2 allows 1 exit in an S1 use on the first floor when the occupant load is less than 30 and the travel distance is 100 linear feet or less.

ii. Second floor 2 exits required 2 provided

1. Should the conference room be relabeled and the design occupant load drop below 30 then two exits will still be required due to travel distance.

2. In the event that the remodel work is done before the addition then the new stairs will need to be revised so that they may be included within the existing building.

i. Occupancy Separation = None Required - ?

i. This is in contradiction to the beginning of your code block data where you called out for Use Group Mixed/Separated (see 2b above).

j. Exit Rating – 1 Hour

i. Will apply to all the exits except those on the east side of the building which is shown to be within 5 feet of a lot line.

3. Sheet A101 – KEYNOTES

a. Note 1; the Simpson tie anchors need to be detailed and identified.

b. Note 3; COLUMN TO BE 1 HR FIRE RATED

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i. Each of the columns or post need to have a 1 hour rating in order to achieve a VA construction type.

ii. Each column that may be subject impact will require protection (IBC 714.4).

iii. Provide a detail for the column wraps.

c. Note 4; NEW COLUMN PADS

i. Verify that the column pads meet the soil requirements based on the soil report.

ii. Provide a detail for the column pads.

d. Note 5; refer to 3.b above.

e. Note 7; WALL TO BE 1 HR RATED

i. Provide a UL listed detail or detail a proscribed method of fire protection.

ii. The existing window in this wall needs to be fire rated.

f. Note 9; EXISTING MTL SIDING

i. The east wall located within 5 feet of the lot line will need to be 2 hour rated.

ii. The post and beams located under the siding will need to be wrapped in order to achieve a VA construction type.

g. Note 10; provide a detail of a UL listed wall partition.

h. Note 13; verify that the existing drains are connected to a properly sized oil interceptor.

i. Note 14: the new walls need to have 1 hour rating in order to achieve a VA construction type.

i. Provide a UL listed detail or detail a proscribed method of fire protection.

j. Note 15; the new beam needs to have 1 hour rating in order to achieve a VA construction type.

i. Provide a detail for the beam wraps.

k. Note 16; verify that the existing furnaces heating elements are located higher than 18 inches above the finished floor.

l. Note 22; the existing headers need to have 1 hour rating in order to achieve a VA construction type.

i. Provide a detail for the header wraps.

m. Note 23; the new mono trusses need to have a 1 hour rating in order to achieve a VA construction type.

i. Provide a detail for protection or verification of fire retardant materials.

n. Note 26; provide a detail for the fire protection method.

o. Note 27; provide verification that the existing drywall ceiling has a 1 hour rating.

p. Note 30; provide verification that the existing acoustic ceiling has a 1 hour rating.

q. Note 31; handrails a required to be located between 34 and 38 inches (IBC 1009.11.1).

 

[Examiner]

Maybe you should send the comments to his State Board of Architecture. Are you sure he is a RDP? If so maybe he should be re-examined by the Board. Did he do just houses in the past?

 

[gbhammer]

Yep he is the staff DP for a home builder. Just about 60% of his key notes were either just plain wrong or had insufficient information. The property owner was not pleased when the comments came back, and I had to go onsite to explain to him and the RDP what my comments meant. It was a record to send out a 5 page comment letter.

 

[mtlogcabin]

It would not be V-A con. type unless the entirety of all the supporting members are 1-hour rated

Disagree

Section 602 is where exterior walls that need protection from the exterior side are identified. The fire exposure side is the concern. A building with ample fire separation distance as little or no risk to fire exposure from the outside. The majority of fire exposure is from the interior of a building.

 

[gbhammer]

DisagreeSection 602 is where exterior walls that need protection from the exterior side are identified. The fire exposure side is the concern. A building with ample fire separation distance as little or no risk to fire exposure from the outside. The majority of fire exposure is from the interior of a building.

Type A construction is not defined in the codes it simply means that the structural elements need to be rated. I would submit that table 601 requires a 1 hour rating for 5A con type it does not say you are allowed to rate only one side of a structural element. Table 602 is about the wall and what lies beyond it. The 5A in this case is about support, so a 5A post and beam building only needs to have its primary structural frame rated, the wall which is not bearing does not need to be rated unless 602 kicks in. In the example above they had a wall that was 3.5' from the property line, and as noted they need that whole wall and its structural elements to have a two hour rating.

 

[Examiner]

Turn his incompetent actions into the board of architecture. He is endangering life and property.

 

[steveray]

I am going to bring this back from the dead to expand on it a little.....How is the VA 1 hour rating (of the structure)maintained at the exterior window and door openings? I am not talking opening protectives based on FSD or anything else, strictly how are they protecting the jacks and headers (1HR) with a vinyl window in the hole and no drywall?

 

[mtlogcabin]

Two types of openings, only one by default provide protection of the jacks and headers. What do you think the burn failure rate would be on a double 2x membrane?

705.8.2 Protected openings.

Where openings are required to be protected, fire doors and fire shutters shall comply with Section 716.5 and fire window assemblies shall comply with Section 716.6.

Exception: Opening protectives are not required where the building is equipped throughout with an automatic sprinkler system in accordance with Section 903.3.1.1 and the exterior openings are protected by a water curtain using automatic sprinklers approved for that use.

705.8.3 Unprotected openings.

Where unprotected openings are permitted, windows and doors shall be constructed of any approved materials. Glazing shall conform to the requirements of Chapters 24 and 26.

 

[steveray]

I am speaking about a wall rated for structure (VA) not FSD or any other reason. The framing needs to be protected from fire, not the spread of flame throughout the building. A UL listing for the wall is all well and good, but what to do when it is interrupted is what I am getting at or attempting to.

 

[Builder Bob]

The structural framing for the window openings and headers, doors,etc. usually have king studs with jack studs made of nominal lumber, assuming that at least one of the studs or headers is sized per the table, the char rates for southern yellow pine is about 1 1/4 inches per hour.

While the window may fail earlier in the fire, the structural components of the wall are going to support a load for at least an hour. The issue has traditionally been with light weight engineered lumber (i.e. TJI joist) which may fail within 15 minutes of fire exposure.