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Photograph of an abandoned chimney in an attic. Bracket Chimneys

Gallows brackets & old bracket chimneys = collapse hazards in buildings?

Bracket chimneys:

This article explains what a bracket chimney is, why they are found (usually in older homes), why they are unsafe, and what to do about abandoning, removing or supporting a bracket chimney. We include photographs of bracket chimneys as well as sketches to help you recognize when this unsafe type of chimney is found in a building.

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Bracket Chimney Collapse & Fire Risks

Photograph of an abandoned chimney in an attic.Definition of Bracket Chimney & Gallows Brackets

A bracket chimney is an incomplete masonry chimney, usually made of brick, that does not and perhaps never extended all the way down to a footing and foundation at ground level.

In North America we may find a bracket-supported chimney in an attic or on upper floors of an older home, usually pre-1900. It is possible that a bracket chimney.

[Click to enlarge any image]

In the U.K. and other countries the bracket that supports such a chimney is referred to as a gallows bracket, most-often supporting the upper portion of a chimney (chimney breast or chimney stack) when the lower segment has been removed during building renovations.

A gallows bracket is a right-angled structural support used to carry the weight of a partly-removed chimney, chimney breast, fireplace hearth, or the angled or non-vertical part of a masonry chimney.

As you will read here there are strict specifications for the dimensions, connections, and use of gallows brackets as unless these details are observed there are risks of dangerous chimney collapse as well as fire and potentially fatal CO (Carbon monoxide) poisoning from damaged or unsafe chimneys and flues.

Our photos above show two bracket chimneys in a pre-1900 home in New York. In our OPINION the supporting chimney bracket is unsafe.

Where you find a gallows bracket under a chimney like the one in our photo, it's likely that that chimney originally extended to ground level but its base has now been removed.

A wooden framed "bracket" supports a masonry chimney on and in a building. Current building codes which require that a masonry chimney be self supporting expect that a masonry chimney will rest on a footing below ground level where it is sound and protected from frost, settlement, tipping, movement.

Wood bracket supports for masonry chimneys such as shown in our sketch (left) are often under-designed and lack sufficient strength to carry the weight of the chimney over time. Further, wood chimney supports may decay from leaks, rot, and insects.

As Carson Dunlop point out in this sketch, these chimneys are often inadequately supported and are a collapse hazard.

If the bracket-supported chimney is in use there are very often fire hazards as well.

Inspectors of older homes may find a bracket chimney in the building attic, with no masonry extending to the floors below. Instead, a wood stove or coal stove on lower floors used a metal chimney which passed up through the ceiling above and into the bracket chimney supported on a wood shelf in the attic. From outside the building it may appear that a normal masonry chimney is installed - possibly a false and unsafe assumption.

Bracket supported chimney (C) Carson Dunlop AssociatesWatch out: bracket chimneys or chimney remains supported by a gallows bracket may be unsafe, risking structural damage or even collapse. Because considerable weight of the remaining chimney masonry may be involved the supporting gallows bracket must be of sufficient strength.

Watch out: as we note below, (Richmond, U.K.) Gallows Bracket chimney supports are not permitted and would be unsafe if installed in lime-mortar masonry walls.

On a home where we find a timber gallows bracket the risk of a building fire (if the chimney remains in use) leaks, rot, failure of structural connectors, failure of the supporting brick or masonry wall all add to the risk of a collapse that would damage the building and may harm building occupants.

Fireplace Hearth Support Brackets or chimney breast supports are also referred to in some countries as a gallows bracket.

See details

at FIREPLACE HEARTH DIMENSIONS & SUPPORT

 

Repair alternatives for bracket chimneys & gallows brackets

Support added below a fireplace hearth (C) Daniel Friedman

Options for repair or replacement of bracket or partly-abandoned chimneys or supporting chimney brackets or gallows brackets include:

Bracket Chimney & Gallows Bracket Safety Research

Gallows bracket installation details, adapted from Richmond U.K. cited & discussed at InspectApedia.com

Sketch: illustration of typical gallows bracket chimney or chimney breast support, adapted from Richmond U.K., cited below. [Click to enlarge any image]

Components of a masonry fireplace (C) Daniel Friedman at InspectApedia.com

Above: fireplace parts illustrates brick corbelling supporting the hearthstone.

Gallows Bracket support for chimney breast removal as sold by Teco Products U.K. cited & discussed at InspectApedia.comIllustration: 375 x 375 mm Gallows Bracket from Teco, U.K. cited below.

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Reader Comments, Questions & Answers About The Article Above

Below you will find questions and answers previously posted on this page at its page bottom reader comment box.

Reader Q&A - also see RECOMMENDED ARTICLES & FAQs

Question: identify this H. Waudby Patent 1870 cement / plaster house or chimney part

H. Waudby Patent 1870 concrete/cement/plaster cast opening to chimney, coal chute, or something else (C) InspectApedia.com Hitzler

Do you know what this is? We can see it in the neighbours house through the joist space of the first floor (ceiling of the main level). Perhaps could have attached to a bracket chimney on the second level.

It is not where the current washroom is, not where you would imagine a washroom ever was.

Nothing comes up when I google “H. WAUDBY’S PATENT 1870”. - Anonymous by private email 2021/05/04

Coal chute? Garbage chute? [original source: https://forgottengalicia.com/wp-content/uploads/2013/01/majestic-coal-chute.png ]

Majestic coal chute advertisement at Inspectapedia.com

Moderator reply:

No, though knowing the location and age of the building where this detail was found would be helpful

If you agree I'll find a place to post the photo and invite comments from readers - someone may recognize this in-wall details.

Our default is to keep you anonymous unless you ask otherwise

More photos of more details would be useful

There was a Canadian inventor of that name.

Is the home where this Waudby patented item is found located in Canada?

Reader follow-up:

Yes, please feel free to post. Unfortunately don't have any more photos.
The building is a row house in Toronto, ON, Canada, built in (I think) 1888. Wood frame, you can see the plaster and lath ceiling in the photo.

There is a bracket chimney on the second level at approximately this location.
Yes, I found that too about the suction pump by Waudby, but can't find anything more.

Moderator reply:

Done; we'll see if other readers can identify the 1870 Waudby patent device shown in your photo.

More details about exactly were this is located in the home and observations around that cut-out in the plaster-lath ceiling (?) at the same location would be diagnostic.

My working guess is that Waudby patented a fire-resistant chimney thimble that allowed a woodstove to be connected to a bracket chimney in your Toronto home.

If that masonry device by H. Waudby and patented in 1870 were part of a coal chute you'd be able to find a potential route down through a wall into a basement coal bin - not likely to be in an interior ceiling; and you'd find some black dust or marks nearby where coal passed. If you get more photos and if you can add more details about the history of your home, photos of the home from outside and of its chimneys and roof including where old chimneys may have exited that would be most helpful. 

I've tried genecology research for the Waudby name to identify Canadians born in the earlier 1800s but with no obvious match.

Question: are bracket chimneys approved?

Photograph of an abandoned chimney in an attic.(Apr 12, 2016) Anonymous said:

are bracket chimneys approved for venting per washington codes

This Q&A were posted originally

at BRACING for METAL CHIMNEYS

Reply:

Anon:

The model building codes such as ICC's chapter 10 (that's what's cited and copied in Seattle's 2012 residential chimney code) don't mention the term "bracket chimney"

But that is a common term to describe a chimney like the one in our photo and that's discussed in detail in the article above on this page.

I am not a code official: your local building code official's word is law where you live. However I can give my lay OPINION that bracket chimneys ought to be prohibited for safety reasons, and I note that the model codes include a paragraph about chimney supports relying on a footing. For example

R1003.2 Footings and foundations. Footings for masonry chimneys shall be constructed of concrete or solid masonry at least 12 inches (305mm) thick and shall extend at least 6 inches (152mm) beyond the face of the foundation or support wall on all sides. Footings shall be founded on natural undisturbed earth or engineered fill below frost depth. In areas not subjected to freezing, footings shall be at least 12 inches (305mm) below finished grade.

The requirement for a footing and foundation supporting a masonry chimney would exclude bracket chimneys in new construction.

Question: minimum footing size for a bracket chimney installed on ground floor center of a structure or over a main beam

(Aug 19, 2014) brandon whitney said:

what would the typical minimum footing size be for a bracket chimney or any chimney installed on a ground floor center of structure on main carrying beam located in basement under first floor floor joist? hope this question makes sense we should have been lawyers lol

Reply:

Brandon
Take a look at the page top photo: a bracket chimney has no footing and is supported by building framing. This is not a modern construction.

The footing size for "any chimney" is a bit of a broad question since chimney materials vary significantly in support requirements. Metal chimneys are typically supported by connections to the structure.

Masonry chimney footing requirements depend on soil properties and chimney materials and size and thus weight. So I'm chicken to give a simplistic single answer.

Here is a quote from Chapter 10 of the ICC model code

R1001.2 Footings and foundations. Footings for masonry fireplaces and their chimneys shall be constructed of concrete or solid masonry at least 12 inches (305 mm) thick and shall extend at least 6 inches (152 mm) beyond the face of the fireplace or foundation wall on all sides.

Footings shall be founded on natural, undisturbed earth or engineered fill below frost depth. In areas not subjected to freezing, footings shall be at least 12 inches (305 mm) below finished grade.

On 2018-12-15 by Anonymous

looking for information on Chimney Brick ties

On 2016-10-15 by Jim

Sorry to be a bother. Same chimney, noted before. ....i understand the footing specs. I am on first floor, so easy enough

Does it need to be reinforced by rebar? Secondly, does the material from the footing up have to be masonry, or can steel bars or wooden 4'x4"s be used, one on each corner of the existing bracket chimney to the footing.

I could then frame them in and cover them with wainscotting to match the kitchen. Is this an option?

On 2016-10-15 by Jim

I recently discover a bracket chimney in my kitchen that had been covered up. I would love to use it for a small wood stove. The current supportis nothung but a pallet secured to the wall studs. How it stays up amazes me.

How might i repair and add additional support to this chimney?


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BRACKET CHIMNEYS & GALLOWS BRACKETS at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.


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