WOOD FRAME CHIMNEYS

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Here in the E Coast of US, there are many new homes that include fireplace inserts and wood stove provisions. The developers use wood frame chimneys into which are placed stainless steel chimneys outfitted with spacers to provide an air barrier.

NOW, within the last few weeks, weve had 3 fires in our area of Lancaster County and 2 over in Chester County. ALL were in new homes with these type chiomneys.
Ive been looking into it for a committee report to my Planning Commission. I could find nothing in the BOCA code regarding such construction and neither have I found any ordinances regarding these trypes of structures.
From my own investigation with the insurers, I found that some of these homeowners were using their fireplaces and wood stoves for daily heating of the living space. The fires started from the chimney structures reaching a temperature that allowed ignition.

Anybody have local ordinances regarding the construction and use of these type chimneys? Our homebuilders lobby has a lot of power and they have the legislature so tied up with percs and promises that the legislature wont do jack ****. If I can dig up enough information regarding other states, Provinces or munis taking some control action (like California not permitting cedar shake roofs where fireplaces are installed in a home), I would be most appreciative

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MA has a fairly standardized building code that is used across the state.

The relevant chapters are linked below:

http://www.mass.gov/Eeops/docs/dps/BuildingCode/780036P10.pdf
http://www.mass.gov/Eeops/docs/dps/BuildingCode/780036P21.pdf

Basically, there is a lot of info on masonry chimneys and the portion that relates to the factory made chimneys simply says that they must be "UL Type HT Class A, approved to 2,100 deg F." and that the pipe must be installed IAW manufacturer's directions.

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does an on-site chimney comport with the definitions of a factory-built? Im guessing that a factory built chimney is a single piped unit that has all the spacers and equipt to be "Nailed Up" to a building. More like one of those metal flues they sell with pellet stoves.

Here , in our area, they actually install such a metal tube and then surround it with a frame "box" chimney covered with vinyl siding. They do look phony because many of the actual chimneys only begin about 4 ft off the ground and protrude through the siding wall and arent even visually anchored to the foundation.
I found out that one of the homeowners did have a woodstove that he used to heat a great room and this woodstove was going full blast for days. I dont think these kinds of setups are meant for actual heating support. They are just made for aesthetic considerations.

Thanks fishin, Ill copy those links and put em in a notebook for the next PC workshop.

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I looked around the VT building codes and saw that they reference NFPA 211, (Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances, 2000 Edition
Abstract: Covers the installation and use of chimneys, fireplaces and venting systems.)

I tried to find to find it online, but only found it for sale from NFPA. http://webstore.ansi.org/ansidocstore/product.asp?sku=21100PDF

Maybe you can convince your local board to let you read their copy (assuming they have one).

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Thanks JPB, Ill tell our ecretary to see whether weve got the code and she can buy it for the township library.
Turns out that there wasanother fire on Fri. in Chester County near the Longwood Gardens. WOw, thats 4 in the new year alone. Im amazed, these wooden chimneys arent real new. I wonder if someones been clipping corners?

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Here's a Link (note: 14 page .pdf download) to the Wisconsin HVAC statutes - pretty much same as Uniform US Building Code. One thing I've noticed about chimney fires hereabouts over the past few years is that typically they've been occurring in newer construction/remodeling and/or in conjunction with solid fuel type heating appliances - wood/pellet/corn burners, mostly - and generally have involved improper/inadequate and/or unapproved construction and/or vent and vent surround materials.

Even with an approved, manufactured, UL Certified double-wall metal flue gas exhaust stack, a properly spaced and secured fireproof inner liner is a good idea for a wood-built chimney chase, interior or exterior (especially if the heating appliance is capable of forced draft/fan assisted combustion), particular attention should be paid to seeing to the integrity of vent assembly joints (no flue gas leakage), and "minimum clearances from combustible materials" are just that; minimum acceptable.

Post-fire inspections here often have disclosed less-than-diligent compliance with requirements, and to my recollection, I don't think I've ever seen a chimney fire involving a system that was "over-built" in respect to "minimum requirements". A real frequent post-fire circumstance is discovering that at some point in the structure clearances inside a "decorative" chimney enclosure were at or below "minimums", joints/joins in the metal flue gas exhaust stack were substandard, and the decorative structure did not incorporate an interior fire-proof sheathing.

Dunno if any of that helps you in your situation,but its stuff we've been wrestling with at town board meetings here the last couple of years.

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Timber-yep that helps a lot. Ive been talking to the insurance carriers so I believe that the"post fire" investigations were thorough.(Im amazed that none of the insurance carriers Ive talked to has volunteered any advice about whether they will, by deeming something "Unisnsurable" help reduce the number of fires.
Ive been tabbing up some fires from this year and from all the fires in the 5 county area , information of which I got through the newspapers as ell as the townships, about >50% were homes less than 10 years old and all of those had chimney surrounds to hide the SS smoke chimney , without which does make it look rather industrial. Since all the Homes in this area strive for a more colonial look (with the exception of the "great room" feature), they cover the chimneys and the fireplaces butt out of the walls like a bay window.

SInce most of the 4 houses that burned in the Lancaster Chester County area since New Years, all were vinyl siding and the vent problem is , as you noted , possible an assist to catching fire by venturi effects

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farmerman wrote:

does an on-site chimney comport with the definitions of a factory-built? Im guessing that a factory built chimney is a single piped unit that has all the spacers and equipt to be "Nailed Up" to a building. More like one of those metal flues they sell with pellet stoves.

Here , in our area, they actually install such a metal tube and then surround it with a frame "box" chimney covered with vinyl siding. They do look phony because many of the actual chimneys only begin about 4 ft off the ground and protrude through the siding wall and arent even visually anchored to the foundation.
I found out that one of the homeowners did have a woodstove that he used to heat a great room and this woodstove was going full blast for days. I dont think these kinds of setups are meant for actual heating support. They are just made for aesthetic considerations.

Thanks fishin, Ill copy those links and put em in a notebook for the next PC workshop.

MA doesn't regulate the building of the wood frame structure of the "chimney" (which is really just a framed chase) other than the normal code for structures. The sizing of the chase is fairly critical though. The clearances between the framing members and the metal pipe itself had to meet the requirements of the metal pipe maker. Most pipe maker's require firebreaks within the chase itself too.

Do you know if the houses that had fires were using the type HT pipe? It would be interesting to get inside one of them and see how it was built.

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They were a;; 304 stainless. That seems pretty common. However the "packed" asbestos pipes arent generally available except by the AMish contractors. I suppose that the contractors wrap the SS pipes with asbestos wrapping. Im not sure, as I didnt gather anything from the insurance investigators. Of course I, sure that theyre not telling me everything until the cases have been settled.

Quote:

MA doesn't regulate the building of the wood frame structure of the "chimney" (which is really just a framed chase) other than the normal code for structures. The sizing of the chase is fairly critical though.

Thats the whole issue here. Most of the site built "chimneys" seem to follow roughly the same dimensions. The centralizers are these rings with ears on that hang the pipe inside the chase. They can conduct heat and , with Timbers point about draft, Im sure that vinyl siding lets lots of air through and the framing of the chi,mney looks like 2X4 with OSB sheeting. Ive never seen any of these chimneys with anything like tyvex. (I suppose they should use an asbestos sheeting on the inside. Seems like a double walled masonary chimney would be lots less trouble and much more forgiving (not to mention safer).

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farmerman - do you have any idea on how old these houses were? 3years? 30 years? I know you probably can't be exact - just looking for a wag.

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A manufcturer website with some information...

http://www.jenningsheating.com/Chimney_Pipe/chimney_pipe.htm

In reading it, it seems there are different heat ratings for the products out there.
A sudden rush to use cheap substandard chimney pipe perhaps?
Or the pipe isn't rated for constant use?
Or substandard construction in the recent housing boom?

Quote:

The SuperPro 2100 factory built chimney is suitable for use with all wood burning appliances in accordance to the American National Standards Institute, Inc. and the National Fire Protection Association (ANSI/NFPA 211) Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances. The SuperPro Chimney meets the Type HT requirements of Underwriters Laboratories, Inc. Standard ANSI/UL 103.HT. The listing of the SuperPro 2100 Chimney items, chimney sections, tees, and elbows are listed by UL and marked in accordance with their requirements. The minimum 2" clearance to combustible enclosure walls is prominently shown on the UL labels provided on all component parts. The minimum clearances shown are proven safe during the UL fire tests conducted with the component supports and spacers in actual contact with combustible framing. Proper installation must be followed with the instructions provided with each support assembly.

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Im thinking that it was the constant use issue. I remember some wood stoves we had that had the stovepipe glow cherry red when the fire was hot and the damper closed, presumably it went this way for a few feet into the hearth.

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Here in Ontario you cannot get home insurance if your only heat source is a wood burning stove. Most people who heat mainly with wood have electric baseboards installed just to get around that. We are putting a high efficiency low-emissions woodstove in our hunt camp and will get it WETT certified to keep our property insurance within reasonable limits. Are you familiar with WETT certification? "The Wood Energy Technical Training (WETT) program is a comprehensive series of courses covering installation codes, proper installation, maintenance and inspection procedures." Makes me wonder if those chimneys were installed by properly trained people. Also the fact that there is a "bend" in the chimney (out and up) can cause problems if they're not maintained/cleaned regularly. We've been reading up on all this in a government publication from Natural Resources Canada. There's information on their website: www.burnitsmart.org.

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Not familliar with WETT. Im quite new at this whole inquiry, and Im getting more and more convinced that people were using their stoves way beyond a reccomended time and the chimneys werent able to take the heat

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Heres some info on installing wood stoves.

Regulare stove pipe requires 18" clearance compared to the insulated pipe. That would probably be your glowing red pipe, farmer.

rules for flue pipes in Canada

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The "glowing red pipe" is not uncommon. Id ventuer to ay that anyone whose had a wood stove has experienced that feature at least once. Since my home is over 200 years old with chimneys in which one can stand up, we know that these babies were installed to be used all the time. Weve had them all relined but theres no wood in the chimneys at all (except for the original "smoke shelves" which were part of the original Rumford Fireplace design.
Today, I was at a job site and noted that , in the area were a number of large new homes. Many had thee frame chimneys and a few had frame chimneys that were stuccoed or covered with this "manufactured stone" So the chimney frames themselves have to be, as you say, isolated with some sufficient gap. However, as Timber or fishin mentioned a few posts back, keeping it so that no venturi action begins to stoke a a fire by superoxygenation. Even in a masonary fireplace with a flue that is also masonary , its common to have chimney fires that , while they usually dont do any damage , can be frightrening because the fire is inside the flue, burning any creosote dross off the flue and the air comes from chinks in the mortar from the outside wall of the building. My neighbor had a chimney fire about 15 years ago and he called me for help . When I arrived, his chimney was making a roaring sound and belching smoke out the top with sparks like a blast furnace. Had this bee a new house, itd been involved in a major fire. My neighbor had to get his chimney relined and he had a mason go and repoint all his brick facing on that side of the building

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You get an old Franklin stove goin' real good, and the puppy roars quite toastily - and both the stove body and the smokestack give off a comforting glow in a dimly lit room - or in an ice-fishing hut or a deer shack. Amazing how big a space one of those will heat to T-shirt temperatures.

Something that's been mentioned bears repeating - creosote buildup is a real consideration, and the moreso the more bends and joins there are in the exhaust stack. Anybody who has a wood-burner had better know how - and when - to clean the exhaust, or contract regularly with someone who does. Another chimney fire hazard is the burning of resinous wood - well seasoned hardwood is best, and there oughtta be a law against burning pine or busted-up shipping pallets in a wood stove (not that that would do much good Rolling Eyes

)

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I love maple, it burns so gently and doesnt put up a big fuss.

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BTW Timber, You have one of those ice fishin houses that you put up and leave on the ice till spring?

Do you build em on site and then tear em down in the late ice?

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Couple buddies and I share one - we trailer it from storage to the lake when the ice is thick enough, where its hauled out onto the ice on 4X4 runners mounted to its bottom sorta like skis. Its about 8X12X8, but its just plywood over 2X4 stud lumber with a "foundation" or sill frame of 2X10s, balloon-frame construction, really, so its not real heavy; 4 guys can wrestle it on & off the tilt trailer with some huffin' and puffin' and a little help from a ratchet winch. Seats 4 or 5 pretty comfortably, twice that many if there's plenty of beer. The floor hinges up from the inside to expose the ice - auger your hole, grab your beverage of choice, and get right to gettin' unbusy. Right now, there's a good 3, mebbe 4 feet of ice under it - folks drive pickups, SUVs, and even RVs right out onto the lakes this time oof year, but our shack we pull on at season start and pull off at season end with an ATV or snowmobile. Some folks do build 'em in place, but most "permanent" shacks are used season after season. I also have a portable shack, which is like a pop-up tent without a floor, more or less - comfotable for one or two, but no ammenities ... the big shack has folding lawn chairs, a little generator, a couple Coleman lanterns, a 2-burner Coleman Dual-Fuel cookstove and, when we bring a receiver and dish, satellite TV - along with that Franklin stove Laughing

In the portable, seating is on overturned buckets, and when there is heat, its from one of those catalytic heaters that use disposable propane bottles - provided I remember to bring it and some canisters Rolling Eyes

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WOOD FRAME CHIMNEYS

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