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Horizontal furnace in a crawl space.

D

DNA

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Sep 7, 2022
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14
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Bayfield Colorado
Greetings everyone. Some time back I seem to recall a requirement for fire protect ion of the floor system if a gas fired furnace was placed in a crawl space. Now that I am looking for that code section , I cannot seem to find it.
Does this requirement actually exist or is my feeble old mind making things up?
 
Not that I'm aware of. If it is in the attic of a sprinklered building, a head is placed above it. Might be a good idea if the building is sprinklered to do that in a crawlspace also.
 
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This is a SFR and my mind must be making things up again, but I could swear I thought there was a gyp, bd. requirement for the bottom of the floor joists or some kind of separation requirement.
Thanks for your response.
 
DNA said:
Greetings everyone. Some time back I seem to recall a requirement for fire protect ion of the floor system if a gas fired furnace was placed in a crawl space. Now that I am looking for that code section , I cannot seem to find it.
Does this requirement actually exist or is my feeble old mind making things up?
Click to expand...
If IRC, 2018 302.13 may be what you are thinking of.
 
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2018 IRC
P2904.1.1 Required sprinkler locations.
Sprinklers shall be installed to protect all areas of a dwelling unit.

Exceptions:

1. Attics, crawl spaces and normally unoccupied concealed spaces that do not contain fuel-fired appliances do not require sprinklers. In attics, crawl spaces and normally unoccupied concealed spaces that contain fuel-fired equipment, a sprinkler shall be installed above the equipment; however, sprinklers shall not be required in the remainder of the space.
 
R302.13 Fire protection of floors. Floor assemblies that are not required elsewhere in this code to be fire-resistance rated, shall be provided with a 1/2-inch (12.7 mm) gypsum wall-board membrane, 5/8-inch (16 mm) wood structural panel membrane, or equivalent on the underside of the floor framing member. Penetrations or openings for ducts, vents, electrical outlets, lighting, devices, luminaires, wires, speakers, drainage, piping and similar openings or penetrations shall be permitted.

Exceptions:

  1. Floor assemblies located directly over a space protected by an automatic sprinkler system in accordance with Section R313, NFPA 13D, or other approved equivalent sprinkler system.
  2. Floor assemblies located directly over a crawl space not intended for storage or for the installation of fuel-fired or electric-powered heating appliances.
  3. Portions of floor assemblies shall be permitted to be unprotected where complying with the following: 3.1. The aggregate area of the unprotected portions does not exceed 80 square feet (7.4 m2)per story. 3.2. Fireblocking in accordance with SectionR302.11.1 is installed along the perimeter of the unprotected portion to separate the unprotected portion from the remainder of the floor assembly.
  4. Wood floor assemblies using dimension lumber or structural composite lumber equal to or greater than 2-inch by 10-inch (50.8 mm by 254 mm) nominal dimension, or other approved floor assemblies demonstrating equivalent fire performance.
 
Last edited:
mtlogcabin said:
2018 IRC
P2904.1.1 Required sprinkler locations.
Sprinklers shall be installed to protect all areas of a dwelling unit.

Exceptions:

1. Attics, crawl spaces and normally unoccupied concealed spaces that do not contain fuel-fired appliances do not require sprinklers. In attics, crawl spaces and normally unoccupied concealed spaces that contain fuel-fired equipment, a sprinkler shall be installed above the equipment; however, sprinklers shall not be required in the remainder of the space.
Click to expand...
In our jurisdiction, sprinklers for residential are not required until you build over 5000 s.f.
 
Sifu said:
If IRC, 2018 302.13 may be what you are thinking of.
Click to expand...
Ok. I get it now. ...this section applies to all floor assemblies unless it falls under one of the exceptions... Damn, what have I been thinking.
Thanks for putting up with my inquiries and thinking it through out loud.
 
DNA said:
Ok. I get it now. ...this section applies to all floor assemblies unless it falls under one of the exceptions... Damn, what have I been thinking.
Thanks for putting up with my inquiries and thinking it through out loud.
Click to expand...
I put up with a lot of things I wish I didn't have to. Thoughtful questions are not one of them. You won't find many people on this forum who ask more of these types of questions than me, so keep them coming, that way I won't feel so alone.
 
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302.13 is aimed at open-web floor trusses or wood I-joists.

Exception 5 applies to conventional solid wood joists. I don't know why 2 x 10 is the minimum size, unless nobody builds smaller homes anymore where 2 x 8s are structurally adequate.

Gypsum board above a fuel-fired furnace might provide a little protection if the furnace malfunctions, but it would have to extend several feet beyond the furnace to do any good.
 
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