Thread: Fireplace clearance

Hi Folks...got a quick question. Does anyone know of a maximum distance that a freestanding wood stove can sit from the wall behind it? Attached is a pic. It seems that the space between the back of the woodstove and the wall behind it should not be accessible. Any thoughts?

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I believe there should be an 18" gap or a nonflammable wall with a 1" air gap against the wall behind the stove.

Originally Posted by Ron Bishop

Does anyone know of a maximum distance that a freestanding wood stove can sit from the wall behind it?

There are MINIMUM clearances, no maximum clearances.

It seems that the space between the back of the woodstove and the wall behind it should not be accessible.

And the back is some how more dangerous than the exposed sides?

gotcha...thank you Jerry.

The stove should be listed to UL 1482 and certified to EPA Phase II. If not, it should be removed.

Is that a combustible wall?
Combustible floor?
What kind of chimney?
How connected?
Connector clearances?
Floor protection?
Level II inspection on chimney?
Listed liner?

What are the stated clearances on the stove?

Normally, if unlisted, you go by NFPA 211. However, being this stove is located in Calif. it should be listed and EPA certified.

From looking at the picture it looks like the legs of the unit are less than 6". If the legs are between 2"-6", the floor under the appliance needs to be protected with one course of hollow masonry units not less than 4 in. in nominal thickness, laid with unsealed ends and joints to provide circulation and a minimum clearance from the legs to the combustable floor of 18" per NFPA 211 12.5.1.2.2 If the legs are 6" or higher than the floor under the appliance needs to be a minimum of 2" of solid masonry units. NFPA 211 12.5.1.2.1

If the back wall is combustible you will need 36" of clearance. However, if the back wall is made of 3 1/2" thick masonry and has a 1" air space between it and any combustible material behind it, you can reduce that clearance to 24". There are also other forms of protection that can reduce the clearance further. But, you will need to figure out what the back wall is built out of to determine. NFPA 211 12.6.2.1

Originally Posted by Ron Bishop

Hi Folks...got a quick question. Does anyone know of a maximum distance that a freestanding wood stove can sit from the wall behind it? Attached is a pic. It seems that the space between the back of the woodstove and the wall behind it should not be accessible. Any thoughts?

Many wood stoves are listed by the Underwriters Laboratories (UL) for miminum clearances to combustible surfaces. As a rule, stoves that aren't rated should have a clearance of 48 inches from combustibles on all sides and 60 inches above. There must be a minimum of 18 inches of clearance from the exposed metal flue pipe. A 36-inch clearance is acceptable from walls that are covered with fireproof materials such as masonry, ceramics, or properly installed metal plates. Freestanding wood and coal stoves typically rest on legs, which must be placed on concrete or masonry of sufficient depth to protect wood or combustible floors below. It's important to be able to recognize dangerous situations.

Robert, can you provide your souce for your recommendations?

Also, how do you define "fireproof" and how does this apply with regards to clearance reduction systems. All references would be greatly appreciated.

TIA,
Bob

On a closely related subject, my son had us over for dinner last night and built a small fire in one of those open portable fire pits. The bottom of the fire pit is on raised legs, about 12" above the ground or surface, in this case above the wood deck. The heat from the fire boiled sap out of the pressure treated deck boards beneath the pit. I was surprised at how hot the wood had become with only a small fire. He would like to continue using the pit on the deck so I am looking for the best way to protect the wood deck from heat. I think the open core 4" cmu's would work, but would like your opinion.

I don't know Vern. We have one too but we have a brick patio and I get some 4 alarm blazes going in that sucker. Even with a small fire, I can't say I'd ever feel comfortable using it on a wooden deck. Are you talking about raising the pit higher off the deck surface with the blocks? Unless the wheels and/or support legs for the pit are secured to the blocks, all it would take is one bump to topple the whole apple cart and really create some excitement.

Your son should be happy he doesn't have the plastic composite Trex type deck boards. They'd probably melt.

Originally Posted by Bob Harper

Robert, can you provide your souce for your recommendations?

Also, how do you define "fireproof" and how does this apply with regards to clearance reduction systems. All references would be greatly appreciated.

TIA,
Bob

My souce was from Mechanical Inspection, Part 1 study unit for TN Home Inspection licenses. I am new to the home inspection business and thought it might be of help. Listed below I found two related topics on wood stove clearances one is CPSC and the other is HEARTH.COM ARTICLES.




NEWS from CPSC

U.S. Consumer Product Safety Commission

Office of Information and Public AffairsWashington, DC 20207
FOR IMMEDIATE RELEASE January 29, 1981 Release # 81-006
Consumers Reminded To Save Energy Safely When Using Fireplaces And Wood Stoves

WASHINGTON, D.C. (January 29) -- The U.S. Consumer Product Safety Commission today issued a mid-winter safety reminder to consumers who are trying to reduce their home heating costs this season by using fireplaces and wood stoves.
In addition to emphasizing a consumers' list of safety precautions related to wood-burning appliances, Commission staff has added a caution for consumers who may be creating a safety hazard they didn't expect while trying to improve the efficiency of their fireplaces.
Consumers increasingly are trying to improve their fireplace performance by installing glass doors or fireplace "inserts." Both of these accessories are used to reduce the quantity of heated room air which escapes up the chimney. The fireplace insert, a wood-burning device which fits into an existing fireplace, adds additional heat from radiation and natural or fan-forced convection.
These accessories, however, may cause problems with "factory-built" fireplaces, a product which is relatively new to the marketplace. For safety, householders should add only those accessories designed or approved for their particular fireplace. Use of other accessories may block crucial air vents, create excessively high temperatures in the fireplace or cause other dangers.
Factory-built fireplaces are prefabricated metal units which are installed complete with chimney. They have been used widely in recent years in new home construction because they are less expensive than traditional masonry fireplaces. They also are called "zero clearance" fireplaces because they can be installed safely next to walls and other combustible surfaces. Some units have a brick or tile veneer which simulates a traditional masonry fireplace.
Installation and operating instructions usually are included with these units, along with information as to whether glass doors or fireplace inserts may be installed safely. But this information may not always reach the homeowner if the factory-built fireplace is installed by the home builder. Consumers who are unsure which kind of fireplace they possess or which instructions apply to the safe use of their fireplace should consult their home builder or fireplace manufacturer or their local fire department.
CPSC also is urging consumers to observe these other safety precautions:

• Fireplaces, wood stoves and chimneys should be inspected once a year to ensure that they are in proper operating condition (i.e., no cracks in fireplace masonry or wood stove linings).
• Use only the proper fuel. Don't use coal in a fireplace or stove that is designed only for wood fires. Never use flammable liquids to ignite a fire.
• Try to keep the fire at a moderate level. Continuous burning of wood at a low-fire level may contribute to creosote build-up, increasing the potential for chimney fires and the corrosion of metal-,parts. Inspect the chimney and chimney connector on wood stoves at least twice monthly and clean if necessary. Avoid over-firing the stove, since overheating may damage the stove and chimney connector or cause a fire in adjacent structures.
• Keep children away from fireplaces and wood stoves. They can be burned badly by touching such hot surfaces as fireplace screens or the exterior of a stove.
• Always keep combustible materials (kindling, newspapers, drapery, etc.) a safe distance from fireplaces and wood stoves.
• When constructing a new fireplace and chimney for your home or installing a wood stove and chimney, be sure that the work is done by a qualified person. If you install a unit yourself, be sure first to check with your local building code officials or fire marshall for installation requirements and recommendations.

The Consumer Product Safety Commission has information on other safety precautions to take when operating or installing wood-burning fireplaces and stoves. This information may be obtained by telephoning the Commission's toll-free Hotline at 800-638-2772.

---

The U.S. Consumer Product Safety Commission is charged with protecting the public from unreasonable risks of serious injury or death from thousands of types of consumer products under the agency's jurisdiction. The CPSC is committed to protecting consumers and families from products that pose a fire, electrical, chemical, or mechanical hazard. The CPSC's work to ensure the safety of consumer products - such as toys, cribs, power tools, cigarette lighters, and household chemicals - contributed significantly to the decline in the rate of deaths and injuries associated with consumer products over the past 30 years.
To report a dangerous product or a product-related injury, call CPSC's Hotline at (800) 638-2772 or CPSC's teletypewriter at (301) 595-7054. To join a CPSC e-mail subscription list, please go to https://www.cpsc.gov/cpsclist.aspx. Consumers can obtain recall and general safety information by logging on to CPSC's Web site at www.cpsc.gov.

//////////////////////////////////////////////

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ARTICLES - Wood - Wood Stove Clearances - Installing it Safely
Wood Stove Clearances - Installing it Safely
Please note: The following document is meant as an introduction and discussion of certain issues relating to Wood Stove installation. Please consult your owners manual, professional installer and building official for more specific information related to your particular installation.
What about Pellet and Gas stoves?
The big difference with wood stoves is that the possible heat output is almost unlimited, while the heat output of Pellet and Gas stoves is controlled by electronics. Wood Stove owners have been known to (wrongly) burn everything from particle board to trash and even certain flammable liquids. Some users even brag about how they made their stove “glow cherry red”! Wood Stoves themselves are not dangerous…rather the installation, operation and maintainence (or lack thereof) can make them so. With that in mind, we’ll try to lead you in the right direction regarding placement of your stove.
#1 Do’s and Don’t
DON’T INSTALL A STOVE DIRECTLY ON A FLOOR WITHOUT LEGS
DON’T CUT THE LEGS OR PEDESTAL OF A STOVE
DON’T BURN ANYTHING EXCEPT NATURAL 100% WOOD LOGS IN YOUR STOVE
DO READ YOUR OWNERS MANUAL AND TALK TO YOUR BUILDING OFFICIAL AND FIREPLACE PRO
DO FOLLOW ALL GUIDELINES AND CODES REGARDING YOUR MODEL
DO INFORM YOUR INSURANCE CARRIER ABOUT YOUR STOVE INSTALLATION
Listed and Unlisted Wood Stoves
Installation requirements are different for stoves that have been “listed”. A listed stove is one that has been examined by a recognized independent laboratory.
If your stove is listed, then it is a requirement that exact floor and wall clearances are specified in the manual. Often these specs are also printed on a metal label affixed to the stove. The good news is that most modern models of Wood Stoves are able to be put closer to walls than earlier models. While older stoves needed as much as 36”, newer stoves can be put as close as 6” to combustible walls with no additional protection needed. This is accomplished by the use of built-in heat shields and combustion designs which project the majority of the stoves heat away from the rear and side walls.
How Hot is Hot?
It would be safe to say that the labs fire up the stoves at a maximum rate - and then some! They then measure the temperature of nearby surfaces. One widely accepted standard states that no combustible surface should rise to more than 90 degrees F above the room temperature. In a 70 degree room, this means that no wall temperature should ever exceed 160 F. Wood does not ignite until 4-500 F although there is some evidence that wood which is constantly exposed to temperatures above 250F can eventually turn to charcoal and present an ignition danger. Keep in mind that certain “safe” temperatures can still cause certain finishes and paints to fail and/or woods and other soft materials to warp or buckle.
The Pipe is Important
Although your newer stove may have reduced clearances to combustibles, the stove pipe (chimney connector) often is the limiting factor. Single wall chimney connector usually has a clearance of 18” from combustible walls. This limitation can often be overcome by the use of special double wall interior piping or stove pipe heat shields, either of which can reduce the pipe clearance to as little as 9”.
All Floors need Protection
All Wood Stoves, listed and unlisted, need protection on the floor. This is commonly known as the “hearth”. The exact type of protection varies depending on the design of the stove and how much heat is radiated downward. Listed stoves which have built-in bottom shields and convection chambers may need as little as 1/4” of ceramic tile beneath the stove. In this case, the floor protection is primarily to catch sparks which might escape during loading and cleaning. Other stoves need more elaborate floor protection. One listed model that we are aware of calls for no combustibles at all beneath their stove unless you use an optional bottom heat shield. This model can therefore only be installed on a concrete slab above bare earth!
Summary for Listed Newer Stoves
It is often possible to install newer Wood Stoves quite close to typical interior wall surfaces without installing any additional non-combustible wall protection. Double wall interior pipe and/or pipe heat shields can also allow your chimney connector to be installed closer to the wall. Check your owners manual for the specific instructions relating to your stove brand and model.

google_protectAndRun("ads_core.google_render_ad", google_handleError, google_render_ad);Older and Non-Listed Stoves
Is my Older Model Stove listed?
If your stove is older than 20 years, it is a safe bet that it is either not listed or that the listing has expired. In almost all cases, you should treat such a stove as an unlisted appliance and follow the general guidelines below.
Am I allowed to Install my Older or Unlisted Stove?
According to the NFPA (National Fire Protection Agency) and other codes and standards, it is permissible to install an unlisted appliance. However, your building official often has the final say in this matter. There are also certain states and localities where installing or using an older stove is not allowed due to the fact that such stove emit much more pollution than newer models.
Floor Protection for Unlisted Stoves (from NFPA 211)
Size: Floor Protection shall extend to at least 18” from all sides of the appliance.
Construction: The basic floor protection specified by NFPA applies to stoves with legs over 6” in height. This means that the floor of the stove combustion chamber should be at least this height above the floor surface. The standard calls for:
1. Closely spaced 2” thick masonry units (brick or cinderblock/patio block.
2. Top cover of 24 gauge sheet metal.
For stoves with legs from 2” to 6” in height, the standard calls for:
1. Hollow 4” blocks set on their side so that the ventilated spaces line up horizontally. The ends should remain open for proper flow of cooling air.
2. Top cover of 24 gauge sheet metal.
Of course, you could use thicker cinderblocks such as 6” or standard 8” if you desire to place the stove higher for easier loading and servicing.
It is this writers opinion that unlisted stoves with very short legs are dangerous and every effort should be made to extending the height of the firebox above the floor. Possible methods include the purchasing of longer cast legs, single bricks under each leg or other similar method. Always remember that maximum air circulation under the stove is the goal.

Floor Protection for Newer Listed Stoves
Listed stoves, meaning those which come complete with attached labels and clear instruction manuals, are to be installed using the floor protection specified by the manufacturer. This can vary greatly, from certain models that cannot be installed on anything other than concrete slabs over bare earth, to others that need just one layer of 1/4” ceramic tile or equivalent. The reason for such a wide variance of specifications is that no standard exists for floor protection. Instead, manufacturers tell the test lab exactly what is in the instruction manual and the lab uses these specs in the stove testing.
Some stove manuals are quite confusing. They give minimums and details using technical terms such as K factor (see our K-Factors Article), which is little help for the average person or contractor. If you are confused about the requirements for your stove model, contact the manufacturer and ask for some examples that would satisfy their floor requirements. You can then use these examples as a basis for your floor protection. Ask the dealer or manufacturer if they sell a bottom heat shield for your model - it will usually be worth the expense since it will save big on the floor construction.
It also helps to study your stove and apply some common sense. For instance, a stove with taller legs or pedestal, an ashpan and/or a bottom convection chamber is likely to produce much less downward radiation than another model with a single wall bottom that the fire burns directly on.
Do I need to provide extra support under the floor for the weight of the stove and hearth?
Not usually. Even though many stoves weigh in at 400+ pounds, the weight is spread by the legs and the floor protection. The combined weight of most systems is not much more than having 4 or 5 people standing in the same area. If you are doing extensive brick and masonry walls and floors you should have an experienced contractor take a look at the joists and posts in the basement or crawl space below. Some relatively simple buttressing will assure that the masonry does not settle and develop cracks.
NOTE: Never attempt to support a masonry chimney on top of frame construction. All such chimneys should have concrete foundations that are installed to code and below the frost line.
Wall Protection
A basic rule which applies at all wall protection is that the least expensive and best insulator is air. This is the reason that most wall protection needs to be installed spaced away from the combustible wall which it protects.
Wall Protection for Unlisted Stoves
As mentioned earlier in this document, most unlisted stoves should be installed 36” from combustible walls. This clearance can be reduced to as little as 12” with the proper wall protection. There are a number of standards relating to such wall protection, so be sure to ask your building official or stove/fireplace pro which are used in your area. One very popular standard is published by the NFPA - National Fire Protection Association (http://www.nfpa.org). This standard is known as NPFA 211, and contains a wealth of information on stove clearances. A sample clearance reduction guide and diagram are presented here as examples:
Clearance Reduction Table
Diagram of Sample Installation
An Example of clearance reduction from this code states that a piece of 24 gauge sheet metal installed on spacers 1” from an existing wall will reduce stove clearances by 66% - or from 36” to 12”. The clearance reduction is usually measured from the rear of the stove to the original combustible wall, not to the sheet metal.
Wall Protection for Newer Listed Stoves
Luckily for the newer stove buyer, most manufacturers have come to understand space limitations in modern homes. The result is that many - if not most - newer stoves are permitted to be placed much closer than 36” to combustible wall surfaces. Some models have additional heat shields that can be purchased which will allow even closer installation. Since each stove is different, you should consult the manual on your specific model. It would be wise to do this research BEFORE your purchase of a stove so that you can be assured your stove will fit your room and hearth design.
Ceiling Protection
Be careful when installing stoves in areas with low overhead clearance, such as basements and rooms with sloped ceilings. NFPA requires 48” from the top of a stove to a combustible ceiling. This can be reduced by use of proper protection. Some newer stoves call for less clearance - we’ve seen models which allow 3 feet and even less. As always, consult the manual for newer and listed stoves.
Alcove Protection
Older and unlisted stoves should not be installed in an alcove constructed of combustible materials. However, some newer stoves allow this installation and have tested their models specifically for this type of setup. This is another situation where it pays to do your research BEFORE selecting a stove model.
Pipe Protection
Stovepipe, also known as chimney connector, has to be a certain distance from both combustible walls and ceilings. One NFPA example calls for an 18” clearance to walls for 6” diameter stovepipe. This can be reduced by either:
1. Protecting the wall or ceiling adjacent to the pipe.
2. Installing an approve ‘Pipe Heat Shield” onto the stovepipe (reduces 18” to 9”)
3. Using special interior double wall stove piping, which can reduce the distance to as little as 6”. This pipe is usually manufactured by the same companies which produce Class A double wall chimney (Metalbestos, Excel, Duravent, etc.).
Once again, your stove manual, label or local professional is the best source of the exact specifications for your particular stove model.
Links:
Prefabricated Stove Pads and Boards
http://www.hargrovegaslogs.com/pad.htm
http://www.gallerystone.com/Etched%20Stove%20Pads.htm
http://www.hearthclassics.com/hearth_pads/index.html
http://members.rogers.com/harthproduct/
http://www.doverra.com/stove-pads.html
Tile Backer and Cement Boards
http://www.jameshardie.com/backerboard/homeowner/hardibacker500.php
http://www.usg.com/brands/drck.asp
Related Articles on HearthNwt
Another HearthNet Article on Clearances
Q and A - 2000+ Questions Answered
Installing a Wood Stove
Stove Manufacturers
Article Originally Posted By: Webmaster On 04/28/2004 at 12:01 PM

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Robert, thanks for providing your references. I kinda chuckled because I wasn't expecting you to cut and paste so much. A link would have sufficed. ;-) Also, you repeated much of the same info. Spero had already posted.

I want to warn you to be very carefule what websites you draw info. from esp. that last one. The owner of the site usually posts info. pretty much by the book but, as you proved, not always. Moreover, when you get into the forums there, he often goes way off from codes, stds, and listings so just caveat emptor on that site.

Two numbers you provided caught my eye: 48" is NOT from NFPA 211, nor is 60" so I'm not sure where they got those numbers or what they were smoking. The max. clearance to combustibles from an unlisted stove per 211, 2010 edition is 36".

Are these two numbers possibly in your Tn. Mech Insp. Std.? If so, you ought to notify them they are incorrect.

FYI, some listed stoves require more clearance than as required in 211 so you go by the more restrictive requirement.

FYI, you cannot install woodstove inserts into factory built woodburning fireplaces. Also, these fireplaces should NEVER be referred to as "zero clearance" because most do state some required clearances to combustibles on most sides, top and nailing flanges. Usually, only the floor carries a true 'zero' clearance.

Listes woodstoves may be placed closer than 12" to a combustible wall ONLY if using the listed attached heat shields installed to the listing. You cannot use approved clearance reduction shields to get a stove closer than 12" to a combustible wall.

I advise you drop the use of that term "fireproof". Nothing on earth truly fits that description. We use "combustible" versus "non-combustible" as defined in NFPA 97 and repeated in NFPA 211. The simple test is if the material has passed an ASTM E-136 test. However, untested materials such as brick or stone are generally considered non-comb. Plastered combustible walls receive no derating and are considered "combustible" just as type 'X' drywall is, too.

I advise you take the FIRE course for Home Inspectors when you get a chance.

Take care and good luck,
Bob

F.I.R.E. Certified Inspector and Associate Instructor
NFI Certified Master Hearth Professional and Sr. Instructor
F.I.R.E. Certified Technician Co-Author and Associate Instructor
NCI Certified Carbon Monoxide and Combustion Analyst
Vice Chairman of the International Association of Fireplace and Chimney Inspectors
Member UL Standards Technical Panels 103 and 1370
Hearth, Patio, and BBQ Association Technical Advisory Cmte. and Government Affairs Cmte.

Great information guys, Thanks. Long time reader, first time responder.

Bob, I am interested in taking the FIRE course you mentioned. I am weak in wood burning stoves and could always use additional fireplace information.

Where can I go for more information?

Thanks

Dan,

Check out this site: F.I.R.E. Certified Inspector