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Unsafe woodstove installation (C) Daniel FriedmanFire Clearances, Installation Standards, Codes for Coal Stoves, Pellet Stoves & Wood stoves
Fire clearance distance reduction using heat shields

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Woodstove fire clearance distance specifications:

This article describes fire safety distances required between wood stoves and coal stoves and the nearest combustible surface. We discuss child safety zones around wood and pellet stoves, the fire clearances for listed and un-listed wood or pellet stoves, and the construction and installation of a heat shield to reduce the required fire clearance distances around wood heating appliances.

The article includes standards for wood or pellet stove installations for various countries and it concludes with photos and descriptions of unsafe wood stove installations.

We discuss fire clearance distance specifications for wood stoves or coal stoves. Wood stove & pellet stove installation codes & standards, listings, labels, certifications. Wood stove or pellet stove heat shield construction & installation specifications.

Examples of unsafe wood stove installations. Comments on NFPA 211 "Standard for Chimneys, Fireplaces, Vents, and Solid Fuel-Burning Appliances".



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Fire Clearances for Flues for Woodstoves & Coal stoves

Unsafe woodstove installation (C) Daniel FriedmanOur photo (above) shows an unsafe wood fireplace installation that lacks adequate clearance from combustibles. Notice also that the connection between the fireplace top and the flue is upside-down and that considerable leakage has occurred out of the flue onto the fireplace top.

Some basic rule of thumb fire clearances for woodstoves are shown in the sketch at left. (Click to enlarge the image).

Watch out: Check with your local fire marshall about local building code requirements for fire-clearance distances before installing and using a wood stove, coal stove, or other auxiliary heat source. Making a mistake can lead to a dangerous building fire.

Article Contents

Child safety: 36" safety zone around Wood Stoves & Pellet Stoves

Use whatever means necessary to create a 36-inch safety zone around any heating equipment that can get hot enough to burn a child. Keep small children out of this space.

Specific Fire Safety Clearance Distances for Un-Certified Wood Stoves & Pellet Stoves

Free-standing fireplace installed by Daniel Friedman (C) Daniel Friedman 1975 - 2015In the U.S. certification is monitored by the U.S. EPA who provide a List of EPA Certified Wood Heaters given below. The Canadian Standards Association (CSA) and the U.S. Wood Heat Safety Organization also provide consistent recommendations for wood stoves that are not carry a certification label. Certifying agencies and standards for other countries are given below.

[Click to enlarge any image]

Fire safety clearance distances are measured from the closest point of the outer surface of the heating appliance to the closest point of nearby wall, floor or ceiling or to other combustible materials that might be nearby. The wall finish surface, such as drywall is not considered in evaluating the heat resistance or fire safety of the heating appliance.

At left is a free-standing wood-burning fireplace installed by the author in the 1970's. Installation was incomplete - no adequate fire shielding was yet provided for this heater. I (DF) lived with this stove as a sole heat source in a different home in the early 1970's and can tell you it is not a design I recommend. I would not install this fireplace today.

Watch out: the free-standing fireplace shown is not a safe installation. While it had a damper controlling the flue to slow burn rate the front of the stove was open except for a screen - a big heat loser for the building as combustion can only be controlled by intelligence: don't build a big fire. And the installation as shown does not meet required clearances to combustibles.

General Fire Safety Clearance Distances for Listed or Certified Wood Stoves & Pellet Stoves

Jotul No. 118 data tag showing fire clearance distances for this wood stove (C) Daniel FriedmanAt left is the permanently affixed certification and data tag from a Jotul No. 118 wood stove that has been in service for more than 20 years in New York. The company's data tag includes woodstove fire clearance distances as marked.

[Click to enlarge any image]

Watch out: Check with your local fire marshall about local building code requirements for fire-clearance distances before installing and using a wood stove, coal stove, or other auxiliary heat source.

Also check the specific fire clearance distance recommendations provided by the manufacturer of your wood burning appliance. Making a mistake can lead to a dangerous building fire. In some jurisdictions for certified woodstoves clearance distances permitted may be as follows:

Clearance distances such as those cited above can in some circumstances be reduced by using proper heat shields of proper material and with proper air spacing and mounting hardware: subject to approval by your local building code official or fire marshall and described below.

In most jurisdictions a building permit and fire safety inspections are required before a wood stove or coal stove can be installed. But we often find that a permit was not obtained and no inspections performed.

Warning: even when a wood or coal stove has been properly installed there are other fire and burn hazards, such as placement of kindling, papers, or furnishings too close to the appliance, chimney fires, and combustion air or (with coal stoves) carbon monoxide hazards.

The following wall and ceiling clearances from woodstoves and similar heating appliances is described by Canada's CSA:

The minimum clearance between any solid-fuel-burning appliance and combustible material (other than the floor), whether or not such material is covered with non- combustible material such as plaster, shall conform to Table 2: Clearances to Combustible Material for Appliances Using Solid-Fuel of CAN/CSA-B365-01, Installation Code for Solid-Fuel-Burning Appliances and Equipment , unless the appliance is certified for lesser clearances.

Certified appliances, accessories, components, and equipment, shall be installed in accordance with the manufacturer’s installation instructions. When a difference exists between the manufacturer’s installation instructions and the CAN/CSA-B365-01, Installation Code for Solid-Fuel-Burning Appliances standard, the manufacturer’s installation instructions shall govern.

And for non-certified appliances

Clearances for uncertified and certified appliances may be reduced in accordance with the clearance provisions of certified heat shields or if the requirements are satisfied as set out in Table 3: Reduction in Appliance and Ductwork Clearance from Combustible Material with Specified Forms of Protection of CAN/CSA- B365-01, Installation Code for Solid-Fuel-Burning Appliances and Equipment
-
retrieved 11/18/2014, original source: http://www.municipalaffairs.alberta.ca/documents/ss/solidfuelpub-final.pdf

Wood stove with inadequate floor or hearth protection (C) Daniel Friedman Wood stove with inadequate floor or hearth protection (C) Daniel Friedman

Above we illustrate what happens if a wood stove or fireplace does not include an adequately-sized hearth or floor protection. It is just about impossible to open the heater to inspect, add wood, or do anything else without risking setting the carpeting or floor on fire. More unsafe hearths and floor damage are shown at FIREPLACES & HEARTHS.

Heat Shield Specifications for Wood Stoves & Pellet Stoves

There are two approaches to heat shield protection to reduce wood heater fire clearance distances

  1. A heat shield is attached to the wood heater itself: CSA Standard B365-1991 Table 3 p. 26 in discussing clearances for un-certified heaters specifies:

    Shielding consists of protection such as external jacketing or metal heat shield attached to the sides and rear of the appliance and spaced out at least 50 mm (2 inches) by non-combustible spacers, with a provision for air circulation at bottom and top.
  2. A heat shield is attached to nearby walls or ceilings.

Wall-mounted Heat Shield Protection: A proper non-combustible fire-protective barrier for a wall-mounted includes a 1" air space between the barrier and the combustible wall.

Mounting hardware for heat shields: The non-combustible wall protection must use insulating and non-combustible mounting hardware that can not conduct heat from the woodstove or its flue to the combustible wall through the barrier.

Air circulation behind heat shields: If air cannot circulate freely behind the noncombustible wall protection the installation is unsafe and not acceptable. Most standards specify one-inch or in some cases 7/8" of air space behind the heat shield.

Watch out: providing an air space may be inadequate fire protection if air cannot circulate freely behind the heat shield. Avoid blocking the openings at the top or bottom a heat shield.

Percentage Woodstove Clearance Distance Reductions By Use of a Heat Shield

Jotul Woodstove installed by Paul Galow (C) Daniel FriedmanAt left is a Jotul woodstove that I (DF) traded to Paul Galow for a fancy wristwatch.

Paul installed air-spaced heat shields of ceramic tile mounted on fireproof board behind the stove and he added a heat shield (the silver contraption) on the side of the stove facing a bed just to slow down the heat in that direction.

More about this wood stove is at WOODSTOVE DRAFT CONTROL

That wood-box on the left side of the stove is a bit close in my OPINION. And the heat shield, really intended as a heat reflector to avoid overheating Mr. Galow's leg (shown in the photo) is itself constructed using a melange of reflective metal and combustible wood as a spacer and as a foot stand.

Watch out: as I've warned Paul, Even if no immediate fire or smoking wall is observed, use of a wood or other heating appliance too close to combustibles can lower their combustion point so that years later during use of the same appliance under what seem to be the same conditions, a fire may occur. See PYROLYSIS EXPLAINED for details.

In my OPINION this is not a safe heat shield. Like many wood stove users, P.G., the owner has chosen to exercise caution and attention for more complete and effective heat shielding - an approach that we've seen successful until a new, less informed or less cautious occupant uses the installation.

According to Wood Heat Safety Woodheat.org Original source: http://www.woodheat.org/clearances.html

    1. Sheet metal heat shield, 29 gauge or heavier, with 7/8" (we recommend 1") air space (described below):
      • Reduce side & rear clearances by 67%
      • Reduce top clearance distance by 50%
    2. Non-combustible heat shield such as ceramic tile or equivalent, with 7/8" (we recommend 1") air space (described below):
      • Reduce side & rear clearances by 50%
      • Reduce top clearance distance by 33%
    3. Combined non-combustible heat shield as in #2 above, mounted on sheet metal backing as in #1 above. [You can see our combined sheet metal, noncombustible cement backer board and ceramic tile heat shield with air space in the photo at above left]
      • Reduce side & rear clearances by 67%
      • Reduce top clearance distance by 50%
    4. Brick heat shield at wall(s) with 7/8" air space between heat shield & wall
      • Reduce side & rear clearances by 50%
    5. Brick heat shield with metal backing (as above) with 7/8" air space as above
      • Reduce side & rear clearances by 67%

- Woodheat.org Ret: 11/16/2014 Original source: http://www.woodheat.org/clearances.html

Wood Stove or Pellet Stove Certification Labeling

Watch out: when purchasing a woodstove or pellet stove be sure that the unit carries a permanently affixed label certifying that it has been tested for safety by an independent testing laboratory.

Wood stove permanent certification label  Wood stove data tag, U.S. EPA

The US EPA sketch at above left illustrates where you should find the permanent wood stove certification tag and what it looks like. This "EPA Sticker" is not a stick-on label despite the use of that term by some agencies.

EPA temporary wood stove label (C) InspectAPediaIt is typically a non-combustible metallic label that gives the date of manufacture of the wood or pellet stove and includes this text: "U.S. Environmental Protection Agency, Certified to Comply with July, 1988 particulate emissions standards."

Note that nothing in this certification comments directly on the safety of the heating appliance nor its fire safety clearance distances. Those data will generally appear in the wood stove's or pellet stove's installation instructions as well as in your local building codes.

A temporary label giving data about the wood heater's efficiency, smoke output in grams per hour, and heat output in BTU range per hour is also affixed to the stove when purchased.

An example temporary data tag for a non-catalytic wood stove is shown at above-right These data tags are distinct from the wood stove certification tag and give different information.

Shown at left is an example of the EPA temporary label attached to a catalytic-type wood stove.

Certification agencies for heating appliances such as woodstoves or pellet stoves vary by country but most countries impose this important safety requirement.

Below we give sources for wood stove and pellet stove installation and safety standards for various countries.

Wood stove / Pellet Stove Installation Standards & Fire Clearances

NFPA 211 "Standard for Chimneys, Fireplaces, Vents, and Solid Fuel–Burning Appliances"

Reader Comment:

2016/07/15 NHFireBear said: Not sure if you already have this info elsewhere:

NFPA 211 "Standard for Chimneys, Fireplaces, Vents, and Solid Fuel–Burning Appliances" applies to the design, installation, maintenance, and inspection of all chimneys, fireplaces, venting systems, and solid fuel–burning appliances. Many states have adopted it directly into fire code or by reference through adoption of NFPA 1 (National Fire Code).

Under NFPA 211: Clearances around residential "room heaters" (wood stoves) shall be not less than 36 inches above and around all sides, and with adequate legs and floor protection.

However, these distances may be reduced by EITHER the amounts shown in the installation manual for a listed and labeled unit OR the larger distances required in the standard charts for percentage, but not less than 18 inches as wall clearance or 24 inches as ceiling clearance, depending upon materials used and spacing.

Non-combustible shielding materials may be 24-ga sheet metal, masonry (brick/stone), 1/2-inch thick non-combustible insulating board, with or without glass fiber or mineral wool insulation, with or without convection air space behind it.

A ventilated air space allows greater reduction in clearance, i.e., 12 instead of 24 inches to a brick wall, with or without 1-inch ventilated air space. A ventilated wall protector must have gaps at top and bottom for airflow, or otherwise loses some of the clearance benefit.

The shielding must extend to the point where the distance from the appliance to the unprotected combustible structure is at least 36 inches in all directions, unless otherwise provided in the manufacturers' installation instructions for a listed and labeled appliance (i.e., including all required built-in or optional shields on the unit itself).

The floor protection for "combustible floor construction" is spelled out according to height of the legs under the stove. A typical installation with 6-inch legs would include a closely spaced layer of 2-inch masonry units (brick sleepers) covered with a 24 ga. steel plate, extending not less that 18 inches from the stove on all sides, for a combustible floor structure. There is no reason it could not ALSO have an air ventilation layer, if properly constructed for the weight.

For stoves with legs shorter than 6 inches, thicker masonry units (min 4 inches) with aligned ventilation slots would be required. No stove with legs under 2 inches is allowed on a combustible floor, even with a shield, unless listed, labeled and instructed otherwise by the manufacturer.

The unit in the photo with the self-standing deflector would not be an approved installation unless the manufacturer has listed it and provided instructions for installation on a combustible floor, with the 8-inch legs, as shown, UNLESS the slate shown in the photo is supported by non-combustible structure (e.g., concrete). That floor could easily be over 200 degrees for days on end, creating the PYROLYSIS EFFECT detailed elsewhere, if sitting on combustible structure.

2016/07/15 NH Fire Bear clarifies: fire clearance to wall or ceiling reduced by some engineered, properly-designed heat shields

Sorry, I may have mistakenly said "not less than 18 inches as wall clearance or 24 inches as ceiling clearance", which refers to the specific use of half-inch noncombustible insulation board protection without ventilation space,

whereas certain OTHER types of engineered protection may reduce wall or ceiling clearances to as little as 12 or 18 inches, respectively, provided they have a ventilated air space.

See, e.g., NFPA 211(2010): Table 12.6.2.1 Reduction of Appliance Clearance with Specified Forms of Protection. Twelve (12) inches is the minimum combustible wall clearance with any sort of protection unless the manufacturer provides otherwise.

Clearance is measured from the surface of the nearest combustible structure, e.g., the wooden studs in the walls or baseboards or window casings or doors (swung in any position), not from the "limited combustible" wallboard or other "protection".

I only referred to PG's "shield" to identify the photo, not to criticize his ingenuity.

Reply:

Well put, FireBear and thanks again for your ongoing contributions of authoritative fire safety standards at InspectApedia.com. The free-standing heat deflector shown in our photos above and on which you comment was built by our friend and contributor Paul Galow, an old guy who is sometimes a bit less concerned with standard approaches to fire safety than are people who've been to a lot of house fires.

Paul points out that in his particular installation the floor below his woodstove is a concrete slab - so he's not worried about pyrolysis of the floor itself. It's nearby carpet, in this case that would be a fire concern for the floor.

I've been particularly concerned about fire clearance distances and heat shielding between both the woodstove and the flue and nearby plywood T-111 interior wall coverings.

(mod) said:
PG can take a bit of criticism. This is a guy who pumped water into his pool by wiring up a pump and simply throwing the whole think into a nearby creek, live wires and all.

But thanks for clarification - I'll add it above.

Examples of Unsafe Fire Clearances for woodstoves

Woodstove unsafe (C) Daniel Friedman Woodstove by couch (C) Daniel Friedman

Above we illustrate two egregious examples of wood stove installations. The Jotl type woodstove (above left) is installed half in a weird (and improperly constructed) fireplace and half standing on carpeting.

The odd shape of the fireplace was creative but we suspect that it may not have performed well - another reason for adding the woodstove. This is an unsafe installation.

Placing a woodstove in a living room next to the couch (above right) is asking for a fire.

The process and temperatures under which wood deteriorates and becomes more readily combustible is also discussed
at SOLAR COLLECTOR WOOD HOUSINGS.

Convert a Zero-Clearance Fireplace to a Woodstove Installation

Fireplace insert (C) Daniel FriedmanReader Question: who can install a woodstove where we have a zero clearance fireplace?

I'd like your opinion as to what type of contractor I need, or if we need one at all.

We have a 1990's Lindal log home with a heatilator fireplace installed. I believe this is a zero clearance fireplace with no actual masonry except for the faux rock surrounding it.

We would like to have a wood burning stove instead. Either a stove on the hearth with the chimney going back inside the fireplace and up the existing flue/pipe, or remove the entire heatilator fireplace. This is my choice and my husband votes for the prior.

If we remove the entire heatilator, I don't think there is any actual masonry inside the rectangular "chimney".... So, we don't know if this is a major construction project that needs a Mason to do it, or if this is a simple task and a fireplace shop could do it. (Of course we'd have to buy their wood stove.

Can you tell me what kind of company I should be dealing with to take this on? - S.D. 11/30/2014

Reply:

We have moved this question and our reply to a separate article. Please
see WOOD STOVE INSTALL CONVERT

...


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