1" clearance

[Joe Funderburk, CMI]

Did you read it ALL Bob? The part that says "drywall is considered non-combustible by 3 national model building codes"

[Bob Elliott]

Originally Posted by jfunderburk

Did you read it ALL Bob? The part that says "drywall is considered non-combustible by 3 national model building codes"

Take a piece of drywall paper and see if it lights up right now then tell us what happened.

Seriously i read that it is the paper that is flammable and one of the other sites on this thread talks about type x drywall so apparently it is not a good idea to have that stuff in direct contact.

[Joe Funderburk, CMI]

Originally Posted by belliott

Seriously i read that it is the paper that is flammable...

It did not say it was "flammable". It said it was in a category called "limited combustible" and is treated as non-combustible by 3 model building codes.

Someone post a picture of sheetrock with scorch marks on it from any type of vent and I'll change my view.

[Bob Elliott]

I looked at various threads on other boards including the ICC and their are different opinions.

The major opinion, appears to be that it is being enforced at 1 inch in new construction

[Brian E. Kelly]

Originally Posted by jfunderburk

Read all of this and pay particular attention to the last paragraph. Provided Larry's information is correct, drywall is considered non-combustible by 3 national model building codes, I don't care what the b-vent manufacturer's say about it.

http://www.nachi.org/forum/f22/b-ven...34/#post543528

Joe have got a list of Manufacturers installation guidelines you choose to ignore on a regular basis you could share with us????

[Joe Funderburk, CMI]

Brian, I sent an email to the manufacturer challenging their classification of sheetrock as combustible. I'll let everyone know when I get an answer.

[Brian E. Kelly]

Originally Posted by jfunderburk

Brian, I sent an email to the manufacturer challenging their classification of sheetrock as combustible. I'll let everyone know when I get an answer.

Wow Joe you are diligent and that is to be admired my friend. Thank you

Look forward to the reply

[Bob Elliott]

Originally Posted by jfunderburk

Brian, I sent an email to the manufacturer challenging their classification of sheetrock as combustible. I'll let everyone know when I get an answer.

It would be nice to have something solid behind us in our opinions on this as it is something I see all the time , and I am sure you guys do to.

[Brian E. Kelly]

Originally Posted by relliott

It would be nice to have something solid behind us in our opinions on this as it is something I see all the time , and I am sure you guys do to.

I follow the manufacturers installation guidelines Bob. http://www.americanmetalproducts.com/vent/amerivent/faq.htm[/quote

[Joe Funderburk, CMI]

I got an email back from the manufacturer. Essentially, the manufacturer declares what is and isn't combustible. To h*ll with laboratories and testing agencies. It's called, in Latin, anus protectus.

The email text is below.

=====================================

Anything that can be considered even limited combustible material is considered as a combustible material by American Metal Products as well as most of the industry and the venting manufacturers.

Price Grandy
800-669-3190

----- Original Message -----
From: Alpha & Omega Home Inspections, LLC
To: pgrandy@socal.rr.com
Sent: Saturday, September 26, 2009 9:49 PM
Subject: B-vents and sheetrock clearance


On your website, you classify drywall as combustible. Is it not true that:


In the National Fire Protection Association's NFPA 101 Code for Safety to Life from Fire in Buildings and Structures, a noncombustible material is defined as a material that, "in the form in which it is used and under the conditions anticipated, will not aid combustion or add appreciable heat to an ambient fire. "Materials are tested for noncombustibility in ASTM E 136 Standard Test Method for Behavior of Materials in a Vertical Tube Furnace at 750 degrees C. The test exposes small samples of the material to a stream of air heated to 750 degrees C, (1382 degrees F).

The material is deemed noncombustible if:

1) Sample temperatures at no time exceed 780 degrees C, (1436 degrees F).

2) There is no flaming after 30 seconds. 3) Once the sample loses 50% of its weight, there is no flaming and sample temperatures never exceed 750 degrees C, (1382 degrees F). ASTM E 136 is an extremely strict test and under its criterion, few building materials qualify as noncombustible. Two USG Interiors products which do are CERAMIC HERITAGE and most THERMAFIBER insulation products.

In regard to gypsum wallboard, the product's paper facing prevents it from passing ASTM E 136. However, because it does have a demonstrated ability to perform in fire rated assemblies, the NFPA has placed it in a special classification called limited-combustible. This category distinguishes gypsum wallboard from other, more highly combustible products. To qualify as limited-combustible, a material must have a noncombustible structural base or core, a surface less than 1/8 in. (0.3 cm) thickness and a flame-spread rating of 50 or less.

This last requirement can be confusing because the three national model building codes, (ICBO's Uniform Building Code, SBCCI's Standard Building Code and BOCA's National Building Code), all allow composite materials that meet the NFPA's definition of limited-combustible, to be classified as noncombustible.



In His Service,



Joe Funderburk
Alpha & Omega Home Inspection, LLC
Certified Master Inspector
Certified Mold Inspector
803-925-1502 Bus.
704-351-1776 Cell
Tjfunderburk@aohomeinspection.comT
Twww.aohomeinspection.comT

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[Brian E. Kelly]

Wow, quick response Joe.

So Joe, does this mean you are now in the Manufacturers installation guidelines camp???

[Joe Funderburk, CMI]

I'm torn Brian. I wish someone could show me some scorched sheetrock. I've never even seen scorched wood and I've seen these flues in contact with roofing felt, plastic wires, paper, and even a birds nest without any sign of burning. Probably hundreds of times I've seen those types of issues. (Yes, I write it all up with the exception of sheetrock.)

I suspect I'll not change my method. The manufacturer's logic is understandable (CYA), but it creates an unnecessary burden for homeowners to have to fix the issue when I'm not convinced there is a real world issue.

[Bob Elliott]

I suppose it would be ok, if we were able to peel back the paper.

However there is a special Type X drywall that is maybe allowed.
Check out this article for everything you need to know about drywall.
http://home.howstuffworks.com/drywall3.htm

[Larry D. Kage]

Originally Posted by belliott

I suppose it would be ok, if we were able to peel back the paper.

However there is a special Type X drywall that is maybe allowed.

Key word is "MAYBE"...

[Brian E. Kelly]

Originally Posted by bkelly2

B Vent manufacturers will disagree and tell that a 1" clearance is required.



http://www.americanmetalproducts.com...rivent/faq.htm

Can I install drywall or wall board right up against the gas vent?
Quote:
No. Drywall and wallboard are considered combustible materials and should not be installed against the vent including the use of this material to close off the hole around the vent. Type B Gas Vent requires a minimum of one-inch clearance to combustibles. This one-inch is a typical clearance for all brands of Type B Vent, but each section of vent pipe is marked with the clearance required by Underwriter Laboratories, so it should be checked

The key word is not maybe. The makers of B Vent require a 1" clearance, period.

Now if you want to make up your own rules, go right ahead, but man up and say, "I am just making this up because I think I know better."