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Crawl Space Protection

C

Coug Dad

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I have a small one story Type V-B dormatory building of Group R-3 Occupancy (<17 occupants). The building will be sprinklered per NFPA 13R. The combustible attic will not be sprinklered so draftstops will be provided in accordance with 717.4.

My question regards the crawl space below the first floor. Typical wood joist floor construction. No insulation is provided in the floor joists because of seasonal use and no heat or A/C. Can the floor joists be left exposed in the crawl space if no sprinklers are installed in the crawl space. Or, do I need to insulate the joist cavities, sheath the underside of the joists or otherwise compartmentize the crawl space. I am not seeing clear direction in Section 717.

Thanks!
 
If you have less than 17 occupants you use the IRC not the IBC. IRC 302.12 requires draftstopping only when there is usable space above and below the concealed area.
 
I am not sure I agree. Isn't a dormatory with less than 17 is an R-3 under the IBC? I thought that not all R-3 are allowed to switch to the IRC. 101.2 exception, lists one and two dwellings, but not all R-3. 310.0 allows R-4's to jump to the IRC.
 
You are allowed to comply with the construction requirements for group R3 so wallah IRC. It is clearly sated in the commentary "... all congregate living facilities with no more than 16 nontransient occupants... are to be classified as Group R-3... As such, the provisions of the IRC can still be utilized
 
gb - R3 does not = IRC. There are provisions in the IBC for dealing with R-3. The IRC is limited to detached one and two family dwellings and townhouses. To the best of my knowledge, there nothing in the IRC that refers to the structures governed by that code as R-3 units. They are simply referred to as detached one and two family dwelling units and townhouses, not R-3.

R-3 units are dealt with in the IBC.
 
Big Mac said:
gb - R3 does not = IRC. There are provisions in the IBC for dealing with R-3. The IRC is limited to detached one and two family dwellings and townhouses. To the best of my knowledge, there nothing in the IRC that refers to the structures governed by that code as R-3 units. They are simply referred to as detached one and two family dwelling units and townhouses, not R-3.R-3 units are dealt with in the IBC.
Click to expand...
2009 IBC commentary "The intent of the congregate living facility referance is to better define when a congregate living facility is operating as a single-family home. Blended families are now common place and not necessarily defined strictly by blood or marriage. Small boarding houses, convents, dormitories, fraternities, soroities, monastaries and nontransient hotels and motels may be small enough to operate as a single-family unit and would be permitted to be constructed as group R-3 occupancies as intended by the code. The threshold of 16 persons is consitent with the results of the most recent census, which has 98% of all homes in the U.S. containing less than 16 persons..." this runs on for some time but does say as I quoted above that the IRC can still be utilized.
 
OK - gb - I kind of see where you are coming from. However the code commentary goes on to say, those buildings three or less stories in height are not classified as Group R-3 and are regulated by the IRC.
 
Big Mac said:
OK - gb - I kind of see where you are coming from. However the code commentary goes on to say, those buildings three or less stories in height are not classified as Group R-3 and are regulated by the IRC.
Click to expand...
In the context of that sentance it is talking about one and two family dwellings over three stories that are an R-3 use group but cannot be regulated with the IRC.
 
Is the 16 persons based upon the owner's purported occupant load or 200 square feet per person (gross)? There are 16 sleeping rooms and they are stating one per room. 200 square feet per person would result in a calculated load of 30.
 
The IBC states that residential is 1:200. It doesn't differentiate between R-1 / R-2 / R-3 / etc.
 
Coug Dad said:
Is the 16 persons based upon the owner's purported occupant load or 200 square feet per person (gross)? There are 16 sleeping rooms and they are stating one per room. 200 square feet per person would result in a calculated load of 30.
Click to expand...
hmmm that is a good question. How large is each room? 6000 sq. ft. building. 2009 allows actual occupant loads if the AHJ approves.
 
A congregate living facility may be an R3 under certain conditions. "R3" means R3. It does not mean "one or two family dwelling." To put it another way, all one and two family dwellings may be classified as an R3 occupancy. However, all R3 occupancies may not be classified as one and two family dwellings.
 
=

Wouldn't you apply the actual calculated Occ. Load vs.

a "proposed" one?.......I would be very cautious /

hesitant to approve what "they are stating".

=



 
And where do you find the construction requirements for R-3 buildings. How is it that R-4 occupancies that are not one or two family dwellings get singled out for IRC inclusion.

It is the intent of the code to use the IRC for each of the R occupancies that have limited occupant loads. They may have spelled it out poorly, they do that some times unlike you who spells everything out very well, but it is still there.
 
Back to my original question. If we have 20 people and it is not under the IRC, am I required to protect the underside of the joist in the crawl space?
 
NFPA13R, Section 6.6.6. Sprinklers shall not be required in attics, penthouses, equipment rooms, elevator machine rooms, concealed spaces dedicated exclusively to and containing only dwelling unit ventilation equipment, crawl spaces, floor/ceiling spaces, non-combustible elevator shafts where the elevator cars comply with ANSI A17.1, and other concealed spaces that are not used or intended for living purposes or storage and do not contain fire fueled equipment.
 
Coug Dad, in your original question I would say no because you are intalling a 13R sprinkler system you only have to sprinkle the occ. space that is 55 sq feet or more, because you don't have to sprinkle the attic with a 13R system you wouldn't have to sprinkle the crawl. now if it was a 13 system then yes you would have to sprinkle the whole building every area were combustable construction is.

Good Luck

Justin
 
Can the floor joists be left exposed in the crawl space if no sprinklers are installed in the crawl space.
Click to expand...
Under the IBC. Yes

Under the 13R requirements. I don't have a copy in front of me, I don't think so, but will have to check.
 
I know 13R would not require sprinkelrs in the crawl space (or the attice, small closets, etc). The question is if the wood joist in the crawl space can be left exposed or if they need to be covered with a layer of drywall.
 
If you use the IBC then you need to provide draftstopping unless you sprinkle throughout.

Just because you are not required to sprinkle in the combustible concealed spaces does not mean you can use exception 1 or 2 of IBC 717.3.2 those exceptions only kick in once you exceed the sprinkler requirements of a 13R system.

I still believe and will continue to allow the IRC to be used when the thresholds for the R-3 exception are not exceeded, and the building is under 3 stories in height.
 
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