Chimney height & horizontal clearance distance FAQs set#5.

This article series describes the height requirements for chimneys, including rooftop clearances and overall chimney height necessary for proper chimney draft and function and for fire safety.

Recent Chimney Height & Clearance Distance Q&A# 5

These questions about chimney or flue height & clearance from various building features were posted originally at CHIMNEY HEIGHT & CLEARANCE CODE

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On 2019-01-07 by (mod) - How to Find the Current Colorado Chimney Code - or codes for other specific jurisdictions

Bird

A set of downloadable PDF files of chimney codes for varous US and other countries and for smaller jurisdictions is

at CHIMNEY CODES & STANDARDS

Your U.S. state, Colorado, lists the current model building codes that it has adapted in this document

COLORADO APPROVED BUILDING CODES [PDF] - Colorado Government, original source https://www.colorado.gov/pacific/osa/bldgcodes 2019/01/28

You'll see the state has approved the 2015 IBC and the 2012 International Fire Code (IFC) and the NFPA standards (not dated).

That takes us to this code that is in our CHIMNEY CODES & STANDARDS collection cited above:

2015 CHAPTER 5, CHIMNEYS AND VENTS, SECTION 501 (IFGC), [PDF] (2015) Seattle building code, Retrieved 2017/07/22, original source: http://www.seattle.gov/dpd/cs/groups/pan/@pan/documents/web_informational/p2622099.pdf

You have my sympathy: because the code writing agencies need to be paid for their work, and they want to be paid by selling copies of the model building codes, it is increasingly difficult for a consumer, builder, or homeowner to obtain a specific or narrow building code answer without either finding an online copy of the code - which is required to be provided in an "as adopted" form by some U.S. states and jurisdictions - or by buying the entire model code after tracking down which version their state or municipality has approved.

Luckily you have a second option for answers to specific questions: call your local building department or fire inspector, as those local authorities are the final legal code authority where you live.

On 2019-01-25 by Lowrie Bird - chimney height requirement to be above any obstruction within 10 feet

I am considering installing a wood burning fireplace adjacent to an existing wall. wall is in center of home. where can i find a colorado code for how far from peak of roof i can come up with my flue piping

 

On 2019-01-04 by (mod) - does this fail the 3 4 10 foot rule?

Yes it does though I'm not sure quite how serious the specific violation is. Why don't you ask for an opinion from your local fire inspector.

On 2019-01-04 by Steve Power

My wood burning stove chimney is at least 3' higher than any part of my roof but is within 8' of a (hardy plank) chase for my gas fireplace. \

Does this fail the 3', 2' 10' rule?

Steve

On 2018-12-25 by (mod) - Why should the chimney be taller than the wall with a horizontal distance of less than 10 feet?

Saed

The chimney height requirement to be above any obstruction within 10 feet has two purposes:

1. fire safety - this is the main concern, with of course smoke and soot problems secondary

2. adequate draft - avoid interference in chimney draft by wind currents directed by nearby surfaces

On 2018-12-25 by saeid

Why should the chimney be taller than the wall with a horizontal distance of less than 10 feet?

On 2018-11-07 by (mod) - how to apply the 10 foot chimney clearance rule

the 10' rule applies where the line is stretched horizontally 10' from the chimney top opening to the first time it touches the roof

On 2018-11-07 7 by Calvin

OK I have a twin house and we have a old wood burning fireplace that we would like to put a wood insert.

We had the chimney rebuilt to the same height it was (I think its even a little taller) and its a twin house with kind of a pitched shingled roof in the front and flat roof in the back.

The chimney comes out about midway on the front pitched roof so the 10' rule applies where the line is stretched 10' from the chimney to the first time it touches the roof or 10' away from the ridge?

If its the ridge my chimney would have to be maybe 20' tall before it reaches the top of the ridge that would seem to create wind issues.

On 2018-08-21 by (mod) - distance from chimney to swamp cooler

In my OPINON, yes. Though we're really talking about the edge of influence here, the concern is that exhaust from a stove could be drawn into the roof equipment, causing trouble later.

On 2018-08-21 by Anonymous

I am planning to install a Dura Vent double wall stove pipe for a wood burning stove.

The pipe, measured from the outside edge of the pipe is more than 10 feet from the ridge, and more than 10' from the ridge line of the roof.

However, it will be 9' 4" from a swamp cooler located on my roof. Is the swamp cooler considered a "roof structure" requiring the pipe to go 2' higher than the cooler?.

Thanks.

On 2018-08-07 by (mod) - chimney cleareances at rooftop

Aaron you need to clear the roof as shown in the article above; here's an example sketch.

On 2018-07-29 by AaronT

I have a large non-insulated closed in side porch. It extends 10 feet out from the side of our 2 story home. I'd like to put a small wood stove in the porch to occasionally heat it.

The house roof line is double pitched (North-South facing), the porch roof is pitched off the second level of the home (eastward). What is the minimum distance I need to be away from the second level exterior wall to terminate the stove pipe? Or, do I have to extend the stove pipe above the roof line of the 2nd story?

On 2018-06-01 by (mod) - Why should the chimney be taller than the wall with a horizontal distance of less than 10 feet?

Fair question.

1. Fire safety

2. Proper draft without disturbance from air across the roof plane

On 2018-06-01 by Lee duram

Why does a chimney have to be above the building hieght ?

On 2018-04-24 by (mod) - can my neighbor add a second floor right next to my chimney?

Probably not - and probably nobody wants either building to catch on fire.

Check with your local building inspector and ask about extending the height of your chimney

On 2018-04-17 by alberto

my neighbord built a second floor and my chimney is right beside it .Is it legal?

On 2018-10-14 by (mod) - chimney height vs nearby building?

Sorry Darin - I'm not sure I've got the exact question.

Generally a chimney that's more than 10 ft. from a building might still need to be taller than the building roof to avoid downdraft problems from the nearby structure.

But there's not a single chimney height requirement that fits all sites and circumstances: for example there are clearances from walls, windows, roofs.

And there may be site specific needs such as hills or trees that require a higher chimney than minimum.

On 2018-10-14 by Darin

Outdoor firplace chiminey hight requirement 14' from house

On 2018-08-09 3 by (mod) - Chicago chimney safety, codes, authority

Frank,

In my view plexiglass is a plastic product and is combustible.

In most jurisdictions a permit, inspections, approvals are required to install a wood stove.

In Chicago you should contact the building department for help:

By Mail:

City Hall
121 N. LaSalle Street
Chicago, Illinois 60602

By Phone:

Dial 311 (within Chicago)

If calling from outside of Chicago, call: 312.744.5000

On 2018-08-08 by Frank - wood burning stove on a enclosed wooden deck with a plexiglass roof

Neighbor put a wood burning stove on a enclosed wooden deck with a plexiglass roof off the kitchen on the first floor. It is a 2 story house.

The metal chimney extends thru the plexiglass roof about 2 ft.

This worries me because it just seems like a fire waiting to happen and my house is in close proximity...if his house goes up, so does mine. And there are trees and bushes near the chimney also. Is this legal or within Chicago building codes?

On 2018-03-16 0 by (mod) - required height for the chimney above the roof line

2 ft. or more if site conditions require

On 2018-03-14 by Chad

A 250000 btu boiler venting out of a masonry chimney w/clay flue liners what is the required height for the chimney above the roof line. There is nothing within 20ft around the chimney

On 2018-03-08 by (mod) - gambrel roof chimney cleareance distances

Mike, your chimnney top needs to clear the 10 foot rule - 10 ft. horizontal distance from the top of the flue opening to any roof surface.

Do not copy this incorrect metal chimney clearance to a gambrel barn roof that I pass by outside Two Harbors Minnesota.

On 2018-03-08 by Mike

I want to go thru long wall on my Gambrel roofed barn. How do to measure the chimney height against the 2 separate pitches.

The trusses are 12’ tall. The lower steeper section is a 15 1/2-12 pitch and the upper is 3 1/2-12. So I want to go out past the 12” eave and straight up

On 2017-08-23 by (mod) - don't shorten the chimney without concern for draft etc.

Shane

I would not prescribe shortening a chimney for a house I cannot see.

For example it could be 10 ft. above the roof it penetrates but need added height to clear other obstructions or to establish sufficient draft by having enough overall height.

On 2017-08-23 by Shane

Have a chimney that sticks out of roof about 10 ft. Far surpasses the 10-2 rule.

House was built in 1840. Is it possible to shorten the height to the 10-2 rule? It's not wood burning. Only thing in the chimney is the boiler pipe? Thanks

On 2017-02-01 22:53:09.406972 by Lizzy

I have a gas burning furnace and a fire box chimney side by side what are the height requirements for each or space between needed so that both can draft correctly?

On 2016-09-02 15:04:31.484465 by (mod) -

Mel:

Ask your real estate agent how much of a deterrent to the sale of the home will be created by the need for this or other repairs that are of significant cost

. If marketability isn't much of an issue (price or time on market are affected), then an option is to go ahead and have 2 or 3 reliable repair cost estimates from local, qualified contractors.

With that information in hand you have the option of making an allowance on the selling price rather than doing the repair.

Some buyers would prefer to be in charge of the repair as they are more confident it will be done with no shortcuts, and because they can then have a direct relationship with the repair contractor should follow-up work be needed.

A fireplace that doesn't work is something that must be repaired for safety before the fireplace is used, but if the chimney is NOT used by anything else (like a heating boiler) then it does not prevent the home from being safely occupied.

On 2016-08-31 18:57:06.309988 by mel perlmutter

House was built in 1980. I am sole owner. Fireplace has NEVER been used and will never be used by me, but its chimney has its upper 20% to 30% of bricks now defective, breaking, falling down.

I expect to sell this house in 3 to 10 years. I think it is appropriate to get all the damaged bricks removed and have the affected part rebuilt NOW.

Wife does not want to spend money on this project now. She says let new owner fix it, or we fix it just before putting house for sale. ADVICE PLEASE. Reply to mfpdds0@gmail.com

On 2016-08-20 by (mod) - "the last person in" gets blamed: problem

Your inspector is being cautious not wanting you to have a fire or loss.

The fact that a building feature remains "as original" does not mean that it's necessarily the best building practice nor that it meets current safety standards or building codes.

Search InspectApedia.com for PYROLYSIS and you'll read how wood, heated even to low temperatures over a decade or two has its combustion point lowered until it can burst into flame.

If your chimney does not meet chimney height codes and standards then it's not as safe as it could or should be. The chimney height codes are based on experience with house fires and perhaps also are influenced by the effects of roof on draft.

As with many building and other product features or situations, as long as nothing goes wrong, nothing goes wrong.

Keep in mind, too, that any building professional who has an IQ higher than a donut and decent ethics knows that she or he is likely to be the one blamed if there is later a catastrophe at a building they inspected.

For that reason an inspector will usually take some pains to be sure you have heard if they've seen something that unsafe, particularly when anyone with proper training could have *seen* that an unsafe condition simply by directing their eyes towards it.

I call this "the last person in" problem: the last professional to visit a home may be blamed and actually held liable for a later disaster, even one occurring a decade later.

A different point of view, one that worries that inspectors spend your money to reduce their own personal risk, is discussed at https://inspectapedia.com/home_inspection/Other_Peoples_Money.php

On 2016-08-20 by Ray - extend the chimney height in Fulton County Georgia

My home was built in north Fulton county GA in 1990/1991 I moved in June of 1991 I have never modified the chimney or fireplace since the home was built.

I was recently told by an inspector that I should Have a fireplace contractor extend the chimney height to correct code.

I was also told to Have a licensed contractor modify the configuration to provide a minimum of 8 inches on each side of the firebox to the wood mantel.
does this sound like something that is required to be done on a home being sold that has had zero modifications done to these parts of the home since it was built?

3 of my neighbors homes sold within the last 12 months and none of them were told to do any of this and they have the same home?

On 2016-01-2 by (mod) -

Cameron

I would not want to use a liner whose diameter was smaller than adequate - you could end up with a smoky fireplace. If that problem occurs you've put in something expensive that needs to be replaced.

Instead I'd ask my installer about installing an adjustable damper in the flue system.

On 2016-01-22 by Cameron

(Sorry, I forgot to put my name on that question that I just posted.)

On 2016-01-22 by Anonymous

My fireplaces all draft well. I read that for a liner "too" long, I could use a 5 inch liner instead of a 6 inch liner to decrease the draft. Is that something that you have seen?

Would you suggest it? One stove manufacturer stated it as an option to manage over-draft caused by long chimneys, but "for Canada only". Is that due to a law or particular "code"?

Also, with insulated liners, would creosote still represent the same level of risk? And with creosote build-up, wouldn't that just require regular cleaning?

On 2016-01-21 by (mod) - how much distance is too long for a flue?

Cameron

I would give tech support at your chimney supplier to discuss the concern. Though you may have to do a few tricks to first establish draft when lighting the stove, draft may not be the issue as much as cooling and creosote accumulation - a fire risk.

On 2016-01-20 by Cameron

I have a 130 year old house with three masonry fireplaces and all flues in great condition, all of which are in chimneys that are inside the house.

I am planning to put high efficiency wood burning stoves into each of the three fireplaces, each with its own flue, and each with its own new 6" stainless steel and insulated flue liner.

Two of the three fireplaces would have a hearth-to-cap distance of close to 40 feet; one manufacturer that I researched does not allow a distance of over 35 feet.

I am trying to determine if there is a safety issue from having too *long* of a flue. For example, could there be an issue with CO back-draft when the stove is shut down? Any ideas why too long of a flue would be considered a problem?

On 2015-10-19 by Does 10/2 rule still apply when following minimum height table for sloped roofs?

Hi - I have a Cape Cod with a 12/12 slopes roof and a gas furnace on the second floor.

The furnance is situated in the front of the home and the type B vent exits the roof close to the front edge of the roof.

We met minimum height requirements (4 feet in this case) but the cap terminates vertically about four feet below the peak of the roof (which as a ridge vent) and is only about five feet of horizontal distance from the room.

Thanks!

I've seen similar posts but wonder if the height is insufficient as it does not meet the 10/2 rule, even though it meets the minimum height clearance in the table. I also have concerns that products of combusion can meander into the ridge vent and bring harmful waste back into my home.

If this is insufficient, is it acceptable to route the vent pipe horizontally out of the side of the house (maybe a six foot run internally) and then go straight up until I meet the 10/2 rule, and hide the whole thing in a chimney chase that runs up the side of the house?

On 2015-10-19 17:39:58.239754 by Does 10/2 rule still apply when following minimum height table for sloped roofs?

Hi - I have a Cape Cod with a 12/12 slopes roof and a gas furnace on the second floor.

The furnance is situated in the front of the home and the type B vent exits the roof close to the front edge of the roof. We met minimum height requirements (4 feet in this case) but the cap terminates vertically about four feet below the peak of the roof (which as a ridge vent) and is only about five feet of horizontal distance from the room.

Thanks!

I've seen similar posts but wonder if the height is insufficient as it does not meet the 10/2 rule, even though it meets the minimum height clearance in the table. I also have concerns that products of combusion can meander into the ridge vent and bring harmful waste back into my home.

If this is insufficient, is it acceptable to route the vent pipe horizontally out of the side of the house (maybe a six foot run internally) and then go straight up until I meet the 10/2 rule, and hide the whole thing in a chimney chase that runs up the side of the house?

...

Continue reading at CHIMNEY HEIGHT & CLEARANCE CODE - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see CHIMNEY HEIGHT & CLEARANCE FAQs - set #1 of questions & answers about chimney height & clearances

Or see these

Recommended Articles

• BUILDING CODE DOWNLOADS - free downloadable PDF files of building codes & standards
• CHIMNEY CODES & STANDARDS
• CHIMNEY HEIGHT & CLEARANCE CODE
  • CHIMNEY CLEARANCE to NEIGHBORS
  • CHIMNEY CLEARANCE to WINDOWS
  • CHIMNEY HEIGHT for Types L & Type B Vents
  • CHIMNEY HEIGHT EXTENSIONS
  • WOOD BURNING FIREPLACE ROOF CLEARANCE
• DIRECT VENT GAS APPLIANCE CLEARANCES
• FIRE CLEARANCES INDOORS
• FIRE CLEARANCES, METAL CHIMNEYS
• FIREPLACE CHIMNEY ROOF CLEARANCE
• GAS APPLIANCE / HEATER DIRECT VENT CLEARANCES
• GAS FIREPLACE VENT CLEARANCE REQUIREMENTS
• HEIGHT REQUIRED for L VENTS & B VENTS
• SINGLE WALL METAL FLUES & VENT FIRE CLEARANCES
• TYPE B-VENT CEILING FLOOR WALL CLEARANCES
• TYPE B-VENT ROOFTOP CLEARANCE
• WOOD BURNING FIREPLACE ROOF CLEARANCE

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INDEX to RELATED ARTICLES: ARTICLE INDEX to CHIMNEYS & FLUES

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