Thread: Attic Fire Stop

I called out a missing fire stop at the attic penetration of the B vent for the furnace and water heater. The contractor reported back to my clients that a fire stop is not required in this situation. This is a two story house, and the flue penetrates into the attic with nothing between the attic and the first floor.

Did I call this out wrong? I always thought that a fire stop was required when penetrating into the attic space to prevent a fire from climbing up the chase and into the attic. We are using the UMC here in New Mexico.

Similar Threads:

• Short Attic Ladder
• Fire marshal defends departments - Durham Herald Sun
• Fire prompts evacuation at Little Promises - Sweet Home New Era
• MYSTERY FIRE KILLS WOMAN - NW Evening Mail
• House fire on Goulais Mission Road - SooToday.com

Are you asking about fire blocking, draft stopping for floor/ceiling assemblies, penetrations, roof assemblies, within chases, etc?? and/or clearances from combustibles, requirements for air space clearances from all non-metalic, supports, sheilding, etc. for b-vent installations?

These should be in your building codes, (IRC?). Local ammendments may dictate different minimums, such as 8' vertical 12', etc. in addition to floor/ceiling penetrations and roof assemblies.

Then there are the b-vent manufacturer's instructions for bracing and supporting, offsetting from combustible material clearances and clearances for anything non-metalic needed air-space. That kraft paper on your fiberglass insulation in contact and within 1" (under your flashlight) for example. Encircling, contacting one-side, insufficient air space can negatively effect performance of b-vent, creating hot spots, cold spots, ineffective draft, deterioration, etc. Having anything insulative or combustible within that clearance zone is not permitted. Insulation should be restrained and not allowed to make contact there - neither should wood be making contact. Looks to be massive in size compared to flashlight and hand in picture what's the btu ratings for "furnace" and "water heater" anyway?

Tape, "duct", "foil" or otherwise does not belong on b-vent. B-vent is not a "flue".

Manufacturer's installation instructions for the b-vent system and building codes, as well as your fuel gas code will likely also speak to clearances of venting materials, in addition to manufacturer's instructions for the furnace and water heater, in addition to your mechanical codes.

Originally Posted by Jim Robinson

I called out a missing fire stop at the attic penetration of the B vent for the furnace and water heater. The contractor reported back to my clients that a fire stop is not required in this situation. This is a two story house, and the flue penetrates into the attic with nothing between the attic and the first floor.

Did I call this out wrong? I always thought that a fire stop was required when penetrating into the attic space to prevent a fire from climbing up the chase and into the attic. We are using the UMC here in New Mexico.

Yes you called it right.

Just for conversation sake I brought this up with Jerry and someone...I cannot remember. Even though I do not agree on some of the thinking in some situations you called it right.

Now if it is going thru a ceiling and not a shaft then you are covered. You do not need a fire stop on top and drywall around the penetration below. You did say that there is nothing between the first floor and then all the way up and thru the attic so it must be a shaft. If it is a shaft up thru the second floor then you need something at the second floor ceiling height.

And as HG said there is a lot more wrong with it like combustibles touching, duct tape on the pipe etc.

The flue is inside that metal sleeve. The clearances, duct tape, etc. are not the issue. The questions is about the fire blocking / firestop at the second floor ceiling penetration.

There is sheet rock at the first floor ceiling. Ted, do you mean then that if the first floor ceiling is sealed then I would not need to have a fire stop at the attic penetration?

Originally Posted by Jim Robinson

There is sheet rock at the first floor ceiling. Ted, do you mean then that if the first floor ceiling is sealed then I would not need to have a fire stop at the attic penetration?

Jim,

I think that Ted is saying that a fire stop is not required when the flue pipe (say, from a heater or water heater) in a closet goes through the ceiling and into the attic immediately above. When the flue pipe is run through a chase, a fire stop is required. Not sure about your case with the flue pipe located within a sleeve. Does the sleeve run full length?

That's what I thought, about the single level house with a B vent through the ceiling. In a two story with a chase like this, I thought it was supposed to have a fire stop. The sleeve did continue up to the roof line. My reasoning is more along the vertical fireblocking aspect than specifically with the flue. Perhaps I should approach it that way.

Originally Posted by Jim Robinson

That's what I thought, about the single level house with a B vent through the ceiling. In a two story with a chase like this, I thought it was supposed to have a fire stop. The sleeve did continue up to the roof line. My reasoning is more along the vertical fireblocking aspect than specifically with the flue. Perhaps I should approach it that way.

From what I believe , if you have a shaft coming up beyond ceiling height into the attic then it needed to be blocked at the ceiling height of the top floor before the attic no matter what is in the shaft.

I have my questions about all that but those appear to be the rules. If there is a shaft it must be blocked.

1. 2006 International Building Code as amended and referred to as the 2006 New Mexico Commercial Building Code;
2. 2006 International Residential Code as amended and referred to as the 2006 New Mexico Residential Building Code;
3. 2006 Existing Building Code as amended and referred to as the 2006 New Mexico Existing Building Code;
4. New Mexico Administrative Code Section 14.5.1-General Provisions, Section 14.5.2-Permits, and Section 14.5.3-Inspections;
5. 2006 New Mexico Earthen Building Code;
6. 2006 New Mexico Non-Load Bearing Baled Straw Construction Building Standards;
7. 2006 New Mexico Energy Conservation Code;
8. 2003 New Mexico Historic Earthen Building Code;
9. 2006 Uniform Plumbing Code as amended and referred to as the 2006 New Mexico Plumbing Code;
10. 2006 Uniform Mechanical Code as amended and referred to as the 2006 New Mexico Mechanical Code;
11. 2003 Uniform Swimming Pool, Spa and Hot Tub Code Phase III as amended and referred to as the 2003 New Mexico Swimming Pool, Spa and Hot Tub Code;
12. 1997 Uniform Solar Code;
13. 2003 New Mexico Solar Energy Code;
14. 2008 National Electrical Code as amended by the State of New Mexico Construction Industries when adopted by the State of New Mexico and referred to as the 2008 New Mexico Electrical Code, until such time, the 2005 National Electrical Code as amended by the State of New Mexico and referred to as the 2005 New Mexico Electrical Safety Code;
15. 2008 National Electrical Safety Code as amended by the State of New Mexico Construction Industries when adopted by the State of New Mexico and referred to as the 2008 New Mexico Electrical Safety Code, until such time, the 2002 National Electrical Safety Code as amended by the State of New Mexico and referred to as the 2005 New Mexico Electrical Safety Code;
16. And beginning on July 1, 2009 The Green Building Code will be making it's debut.

According to the Santa Fe, NM site, that's a code base list.

B-vent is not "flue pipe". Gas fired appliances are vented. Although they may be vented into a chimney - which can have a "flue". In this case Mr. R said they are being vented via "B-Vent".

The "flue pipe" for example in a Category I gas fired storage type water heater would be within the center connecting the burner chamber to the top of the case (usually containing a baffle) and you can see the termination of the "flue pipe" by looking through the openings between the support arms/legs of the draft hood.

Chapter Contents

NMMC: 14.9.2 NMAC

Other Code rule/law links for NM: NM Construction Industries Division - Rules and Law

HTH.

Our local AHJ does the structural, but not the mechanical inspections. His take on it is that it would need a fire stop if it were enclosed in a framed chase. If there is no chase, then it would not need a fire stop. To paraphrase him, it doesn't make a lot of sense sometimes, but that's how it is worded. The plumber that I work with felt the same way about it not needing a fire stop at the attic penetration, so I guess I was wrong on that one.

I wasn't able to get in touch with the mechanical inspector, but I'll probably just take my lump and move on. As the AHJ said, it's certainly not a bad idea, but not required.

The 'vent', as in 'B-vent' requires listed firestops per the mfrs's listings (both the appliance and vent mfrs.) and fireblocking at each floor or ceiling level-period. The 'firestops' are also spacers for lateral support and to ensure clearance to combustibles, which you obviously don't have here. You would also need an attic insulation shield in this case.

Whether the vent is located inside a chase or not has nothing to do with the requirement for firestops and fireblocking or not. In addition, you'll need fireblocing every 10 feet vertically.

This is a cut and dried issue. Two firestops and fireblocks are required for the case in point, attic insulation shield and remove combustibles including tape. The first firestop should be located at the ceiling level of the first floor. The second firestop should be located on the top of the joists in the attic then the insulation shield over that. Of course, the chase should have vertical fireblocking as needed.

FYI, a 'shaft' is a chase above 3 stories and would trigger fire rated assembly based upon the occupancy in the IBC-not IRC so I'd be careful with that terminology.

The AHJ needs reading lessons or a copy of the code or both.
Bob

In addition to that Bob Harper said, regarding the two required as he mentioned, there are requirements at the roof assembly penetration AS WELL.

Also, since the passage through the occupied 2nd floor is required to be ENCLOSED, it does also matter, and further requires the listed attic floor firestop, ceiling support/firestop at first floor ceiling assembly, and the framing for both penetrations. THIS IS COVERED in MFG instructions for B-Vent type Listed SYSTEMS.

Listed B-venting is a SYSTEM. Manufacturer's instructions MUST be followed.

NM has replaced the mechanical chapters of the IRC with its own Mechanical Code, The NM Mechanical Code IS the 2006 Uniform Mechanical Code with NM ammendments. Chapter 8 of the 06 UMC is adopted into the NMMC without changes.

This defers to mfg instructions and requires even more stringent when using UNLISTED.

ANSI Z223.1 is NFPA 54.

Spacing, clearance, supports, framing of/for and installation of fireblock, insulation sheild, is required, it has everything to do with the photographed installation. BTW similar requirements for shield, support, and square block, and if present insulation sheilding at roof penetration.

Here is a link to one such mfg, simpson duravent. Fig 1 (page 2) is example to THIS installation circumstance, as described (equip on 1st floor, passage through 2nd occupied floor, via insulated attic floor, and roof, interior). Details bottom page 4 starting with #3, see esp. #9.

http://www.duravent.com/docs/instruct/L204A_apr00.pdf

Originally Posted by H.G. Watson, Sr.

[LIST=1]B-vent is not "flue pipe". Gas fired appliances are vented. Although they may be vented into a chimney - which can have a "flue". In this case Mr. R said they are being vented via "B-Vent".

I thought a "flue" was the space inside the walls of the chimney or b-vent and anything that functioned as a chimney or vent was a "flue pipe". I am so confused. Does anyone have a glossary?

Originally Posted by Gunnar Alquist

I thought a "flue" was the space inside the walls of the chimney or b-vent and anything that functioned as a chimney or vent was a "flue pipe". I am so confused. Does anyone have a glossary?

Ted was wrong too even in his one story ceiling and attic above example.

Gunnar,

Adding the word "pipe" after the functional description of "flue" is wrong applied to the instant post.

Terms are defined in the Standards, approval criteria, and the model Codes, and sometimes further as adopted by the jurisdiction.

Here is an easy to read "snippet" from Hart & Cooley's Type B-Vent FAQs:

Is Hart & Cooley B-Vent Fire Rated?

No, Hart & Cooley's Type B gas vent does not have a fire rating. Neither do any of our competitors. The standard for developing fire ratings is ASTM E84. The test method provides a consistent, repeatable test method to report flame spread and smoke development for building materials in response to heat and flame. Results may be used as elements of a fire risk assessment.

Underwriter's Laboratories specify the materials that we use for building our B-vent in their Standard 441 for gas vents. These materials have no ability to ignite or to support or sustain combustion. There is no contribution to the fuel supply. Since there is nothing that can bum, the flame spread rating is "0". Since there is no flame, the smoke density development rating is "0".

Hart & Cooley requires the use of our RSA support in the ceiling above a connected appliance. This support is also a fire stop at that location. UL specifies this to be so. We have been selling this UL listed system and having it installed through partitions in buildings that require fire rated assemblies since 1959 without a problem. UL condones this application. UL has not encouraged us to test with fire rated assemblies since the test would show consumption and degradation of building materials surrounding the B-vent while leaving the metal vent components in place.

Gas Vents (type B and BW) are covered by UL 441. The standard incorporates NFPA 211 and NFPA 54, it further, where applicable as "intended", incorporates other codified and model code language (such as applicable in THE OP's question/case - the Uniform Mechanical Code, should the mfg of the Cat I appliances and/or the mfg. of the b-venting system (b-vent + mfg's b-vent components) have requested incorporated testing/listing services specific or unique for approvals, extra listing requirements, etc.

UL 441 references other standards and incorporates a glossary, there are also writing style and rules to UL standards. Both NFPA 211 & 54 include definitions or "glossaries" and futher define in applied chapters and sections. Category I appliances as defined in the above and other standards and model codes are also bereft with "definitions", "glossaries" and application specific references.

Here is a direct link to the "scope" for UL 441 at UL's site:
Scope for UL 441

Here is a direct link to the "Table of Contents" for UL 441 at UL's site:
Table of Contents for UL 441

You'd have to decide which standards apply to the particular appliance you were interested in and look those up for yourself.

You may review (preview) FOR FREE (register FOR FREE) NFPA 211 and NFPA 54 on-line in view-only mode at NFPA

In those documents you will find definitions and further clarifications on chapters and articles discussing Category I appliances, specifics on types of appliances, further categorized as Cat. I, II, etc. and on Vent, Vents, Venting, Gas, etc.


Think of it as calling or treating a NM Cable assembly as a singular "wire" or "conductor", not a "wiring method", or listed "cable assembly" or incorrectly appling the presumed ratings of the componant "wires" conductors, etc. and not those conditions, limitations, ratings of the assembly as a whole (for which it is listed), and all the times using an incorrect understanding of the many distinctions can result in an incorrect application/installation/level of - or compromise to safety, functionality, etc.

Distinctions with MANY differences, especially in the limitations, requirements, applications, and permitted use and installation of materials.

Terms and the correct use of same are important, especially in applications of safety, manufacturer's instructions, etc.

Category I gas-fired appliances are Vented.

HTH.

I just copied the definitions out of the 2010 NFPA 211 and accidentally erased them and I'm not going to do it again so here are the sections for you to look up:
3.3.73 Flue
3.3.142 Vent
Annex A.3.3.142 Vent

HTH,
Bob

Thanks Bob. That is what I was looking for.

After reading the two NFPA 211 definitions, I believe that flue is still correct, but vent is more accurate.

3.3.73 Flue. The general term for a passage through which gases are conveyed from the combustion chamber to the outer air.

3.3.73.1 Appliance Flue. The flue passage within an appliance.

3.3.73.2 Chimney Flue. The passage in a chimney for conveying the flue gases to the outside atmosphere


3.3.142 Vent. A flue gas-conveying system intended for use only with certain gas-, liquid-, or pellet fuel-fired appliances that do not produce flue gas outlet temperatures higher than a value specified in the listing vent standards.

3.3.142.1 Gas vent. A passageway composed of listed factory-built components assembled in accordance with the manufacturer's installation instructions for conveying vent gases from appliances or their vent connectors to the outdoors.