# IBC 717 Fireblocking



## jar546 (Jul 11, 2013)

Wall studs of combustible wood construction with gypsum board covering that terminates above the drop ceiling but before the top plate(s) on interior and exterior walls.

There is now a gap between the end of the gypsum and the solid wood top plate that is open to the stud cavity below.  This, in turn, allows any fire that starts in a wall cavity, such as an electrical fire to spread to above the drop ceiling with no barriers in place.

At the half way point of the wall, the contractor has some bracing that does not meet the requirements of draftstopping but does block the cavity about 4' off the floor.  The other half is open to the drop ceiling cavity because they did not run the gypsum all the way up to the top plate(s).

We believe that IBC 717 applies, specifically this language in the IBC:



> 717.2.3 Connections between horizontal and verticalspaces. Fireblocking shall be provided at interconnections
> 
> between concealed vertical stud wall or partition spaces and
> 
> ...


Neither the contractor nor the RDP agree with this.

Now for a history lesson on this property that is being renovated with change of use and Level 3.

I don't have all of the particulars but here are the basics.

*The plans were initially rejected for lack of a sprinkler system being added as required.

*The RDP then added a fire barrier to break up the building to circumvent the sprinkler system

*We then stopped the job because the contractor did not follow the prints and started framing exterior walls with combustible wood which was not allowed for the type construction.

*The RDP then changed the type of construction to allow this and manipulated the fire barriers to allow it.

Now they want their cake, they want to eat it and I think they want us to serve it to them on a silver platter.

What you think?


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## Codegeek (Jul 12, 2013)

I think you still have an area which will allow for the spread of fire and as a result still needs fireblocking for the very purposes you quoted in 717.2.3.


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## Builder Bob (Jul 12, 2013)

If you have 16 foot studs with 12 feet of sheet rock with a ACT ceiling at 10 feet, you will need to provide fire blocking and/or bridging at two locations - top of sheet rock and at another intermediate level.....One; The fire blocking requirements requires vertical concealable spaces to be isolated from horizontal concealed spaces. Two: the length of the studs would require bridging ..... either in one or two intermediate spaces along the stud.

The fire blocking is important for two reasons - one as described, it limits the ability of to travel vertically from the wall cavity into the horizontal open combustible space....but almost as important, it prevents burning material to drop down into the concealed spaces of the walls that could allow the fire to spread or rekindle after a fire has been extinguished.


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## redeyedfly (Sep 16, 2022)

jar546 said:


> Wall studs of combustible wood construction with gypsum board covering that terminates above the drop ceiling but before the top plate(s) on interior and exterior walls.
> 
> There is now a gap between the end of the gypsum and the solid wood top plate that is open to the stud cavity below.  This, in turn, allows any fire that starts in a wall cavity, such as an electrical fire to spread to above the drop ceiling with no barriers in place.
> 
> ...


Both the RDP and the GC are wrong and the RDP sounds incompetent.  You never design a building at a higher construction type than necessary.  There is always more cost as you go up.  If they could change the construction type to combustible they should have done that from the start.  

Also, how could they possibly not know vert/horiz fireblocking requirements?


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## Joe.B (Sep 16, 2022)

redeyedfly said:


> Both the RDP and the GC are wrong and the RDP sounds incompetent.  You never design a building at a higher construction type than necessary.  There is always more cost as you go up.  If they could change the construction type to combustible they should have done that from the start.
> 
> Also, how could they possibly not know vert/horiz fireblocking requirements?


Ha! Yes on all counts. Didn't want sprinklers so the upped the construction type and changed the configuration. Then they didn't want to build to their own design! Ridiculous, sounds like its back to sprinklers being required...


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## steveray (Sep 19, 2022)

Are they sprinklering above the ceiling because of the concealed combustibles?


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## mtlogcabin (Sep 19, 2022)

Are the walls insulated ? We usually see fiberglass sound insulation on the interior wall construction that you are describing that fills the entire cavity. 

718.2.1.2 Unfaced fiberglass.
Unfaced fiberglass batt insulation used as fireblocking shall fill the entire cross section of the wall cavity to a minimum height of 16 inches (406 mm) measured vertically. Where piping, conduit or similar obstructions are encountered, the insulation shall be packed tightly around the obstruction.

This section would comply with 718.2.2

718.2.1.5 Double stud walls.
Batts or blankets of mineral or glass fiber or other approved nonrigid materials shall be allowed as fireblocking in walls constructed using parallel rows of studs or staggered studs.

718.2.2 Concealed wall spaces.
Fireblocking shall be provided in concealed spaces of stud walls and partitions, including furred spaces, and parallel rows of studs or staggered studs, as follows:

1.    Vertically at the ceiling and floor levels.

2.    Horizontally at intervals not exceeding 10 feet (3048 mm).


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## Genduct (Sep 19, 2022)

Builder Bob said:


> If you have 16 foot studs with 12 feet of sheet rock with a ACT ceiling at 10 feet, you will need to provide fire blocking and/or bridging at two locations - top of sheet rock and at another intermediate level.....One; The fire blocking requirements requires vertical concealable spaces to be isolated from horizontal concealed spaces. Two: the length of the studs would require bridging ..... either in one or two intermediate spaces along the stud.
> 
> The fire blocking is important for two reasons - one as described, it limits the ability of to travel vertically from the wall cavity into the horizontal open combustible space....but almost as important, it prevents burning material to drop down into the concealed spaces of the walls that could allow the fire to spread or rekindle after a fire has been extinguished.


100 sq ft rule,  right!


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## TheCommish (Sep 20, 2022)

If there is a suspended ceiling and the space above the ceiling and wall at the ceiling line is open, do your need blocker at the ceiling height or is it not a concealed space?  Asking for a friend


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## steveray (Sep 20, 2022)

And again....I would think the sprinklers above the ceiling would (almost) make the fireblocking moot as it does the draftstopping....I know that is not apples to apples, but....

Exceptions:
1. Draftstopping is not required in buildings
equipped throughout with an automatic sprinkler
system in accordance with Section 903.3.1.1.

Similar in this case as the fire/ smoke would be above the drop ceiling in the "attic" space...Maybe the 10' line, but if there is only 2' above that, I don't think that is a big deal...But there I go thinking...


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## Genduct (Sep 20, 2022)

TheCommish said:


> If there is a suspended ceiling and the space above the ceiling and wall at the ceiling line is open, do your need blocker at the ceiling height or is it not a concealed space?  Asking for a friend


The suspended ceiling is not considered in the 100 Sq Ft Rule for the walls.  not installing drywall on the entire wall meets the Code definition of STUPID or DUMB   IMHO


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## jar546 (Sep 20, 2022)

What fire sprinklers above the suspended ceiling?  There are designs that have no fire sprinkler system in the entire building.  Stopping the sheetrock with exposed wood framing above that area is a problem.  Mineral wool in all cavities may be the only solution or hang more drywall.


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## TheCommish (Sep 20, 2022)

Glenduct,

Please explain or cite the 100 SF rule

Stupid or Dumb are not code citable items, i have seen plenty of thing that are short cited however pass the requirements of the codes.


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## Genduct (Sep 20, 2022)

TheCommish said:


> Glenduct,
> 
> Please explain or cite the 100 SF rule
> 
> Stupid or Dumb are not code citable items, i have seen plenty of thing that are short cited however pass the requirements of the codes.


2015 IBC  718.2.6  EXTERIOR WALL COVERING  FOR COMBUSTABLE CONSTRUCTION


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## Genduct (Sep 20, 2022)

Genduct said:


> 2015 IBC  718.2.6  EXTERIOR WALL COVERING  FOR COMBUSTABLE CONSTRUCTION


PS for alterations to IIIB construction with drywall on one side only, it becomes an interesting challenge to provide a good seal between stud and masonry wall  so that we don't have a run away fire (probably electrical) behind the wall


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