Draftstopping Concealed Roof Spaces

[Francis Vineyard]

In your opinion is it the intent for draftstopping in concealed roof spaces as for attic spaces in reference to exception 3 together and can be used with excepton 1 in R-2?

2012 IBC

ATTIC. The space between the ceiling beams of the top story and the roof rafters.

718.4 Draftstopping in attics. In combustible construction, draftstopping shall be installed to subdivide attic spaces and concealed roof spaces in the locations prescribed in Sections 718.4.2 and 718.4.3. Ventilation of concealed roof spaces shall be maintained in accordance with Section 1203.2.

718.4.2 Groups R-1 and R-2. Draftstopping shall be provided in attics, mansards, overhangs or other concealed roof spaces of Group R-2 buildings with three or more dwelling units and in all Group R-1 buildings. Draftstopping shall be installed above, and in line with, sleeping unit and dwelling unit separation walls that do not extend to the underside of the roof sheathing above.

Exceptions:

1. Where corridor walls provide a sleeping unit or dwelling unit separation, draftstopping shall only be required above one of the corridor walls.

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

3. In occupancies in Group R-2 that do not exceed four stories above grade plane, the attic space shall be subdivided by draftstops into areas not exceeding 3,000 sf. or above every two dwelling units, whichever is smaller.

4. (intentionally not provided)

718.4.3 Other groups. Draftstopping shall be installed in attics and concealed roof spaces, such that any horizontal area does not exceed 3,000 square feet (279 m2).

(Exception intenionally not provided)

 

[north star]

@ = @


Francis,

Not sure of your question.......See if this is what
you are asking.

In Section 718.4.2, you want to know if Exception
# 1 & Exception # 3 can be combined to require
draftstopping to: a maximum of 3,000 sq. ft. and
above one corridor wall, ..in the attic spaces and
in concealed roof spaces, versus one of the Exceptions
or the other ?

Thanks !


@ = @

 

[Francis Vineyard]

Can you take exception 3 for flat roofs?

 

[JBI]

Is there an 'attic' below the flat roof?

 

[Francis Vineyard]

Roof/ceilng trusses!

 

[tmurray]

I would consider any space between the top-most ceiling and the roof to be an attic regardless of the slope of roof or the actual space between them, provided there is an interstitial space between the two components..

 

[cda]

Might depend on how built??

Possibly if very flat, no place to put draft stops??

 

[steveray]

"or other concealed roof spaces of Group R-2 buildings"

 

[Francis Vineyard]

"or other concealed roof spaces of Group R-2 buildings"

Exception 3 only mentions attic unlike the other sections.

Would you define concealed roof spaces as "ceilngs without attic space" and cannot use Exception 3; applicable to attic space only?

 

[steveray]

I would say that you get the 2 unit exception if that is what you are asking...

 

[Paul Sweet]

Draftstopping should be provided between units no matter what the code says. There's a lot of kindling wood in trussed attics (or flat roofs), and we have had several fires in sprinklered apartments with unsprinklered attics get into the attic and destroy the entire building. Amazingly these fires haven't killed anybody - yet.

 

[JBI]

Attic is a defined term... The space between the ceiling beams of the top story and the roof rafters.
I'm not sure the spaces between web members of roof trusses qualify. Draftstop above corridors, between units, and call it a day.

 

[JBI]

we have had several fires in sprinklered apartments with unsprinklered attics get into the attic and destroy the entire building

The exception is for fully sprinklered per 903.3.1.1, so a full NFPA 13 system would be required to meet the exception. A 13R won't do.

 

[Francis Vineyard]

Steveray appreciate your straight forward answers in this forum. Draftstopping shown in red in the drawing: 5A, 13R.

 

[steveray]

Thanks Francis! You too!....I typically don't have time for some of the great lengthy answers I see here, but I will throw my 2 cents in when I can. Losing the good cut and pasteability of publicecodes has hurt a bit too...

 

[north star]

% = % = %


**steveray**,

Have you tried using a Snipping Tool from your computer' Desktop ?
I have had "some" success in cutting & pasting from The Cow' website,
and their Codes.


% = % = %

 

[steveray]

NS...I think it worked for me once, but I am so busy right now I don't have time to beat it (a new process) through my head

 

[Paul Sweet]

OT, but 1/8" per foot isn't adequate roof slope.