Fireplaces & Chimneys
The third edition of the Residential Masonry Fireplace and
Chimney Handbook as published by the Masonry Institute of America is now available. This in-depth resource should be considered a must-have for those involved in the construction of masonry fireplaces and masonry heaters. This revision includes a new section addressing masonry heaters and a multitude of drawings, diagrams and photos.
The New Rumford Fireplace
Taking queues from the traditional Rumford fireplace, members of the Brick Industry Association's (BIA) Fireplace and Chimney Committee have crafted a new masonry fireplace based largely on Rumford's principle of efficiency. The result is a simple, easily constructed brick fireplace that uses minimal bricks and space within a house.
"Our main emphasis was to create a fireplace that was efficient in terms of materials and easy to construct," says Charles Clark, AIA, PE, Director of Engineering Services at BIA.
"Time savings and material savings are really tied in together, because the more material used in the fireplace itself means the more time needed to put those materials into place," he continues. Southern Brick Institute's Bryan Light adds, "I would think the savings in time are somewhere around 1/3."
This article will review the history of the Rumford and the basics on how to construct a BIA Rumford fireplace.
First introduced by Count Rumford in the 1790s, Rumford fireplaces were a means of improving the heating capabilities of their traditional large, bulky ancestors. Prior to Rumford, masonry fireplaces had large, deep fireboxes that were rectangular in shape.
Applying his knowledge of heat to the fireplace, Count Rumford reasoned that the traditional masonry fireplace was not as efficient as it could be because it did not reflect much heat back into the room. His first change to the traditional fireplace of the day was to move the rear firebox wall closer to the front of the fireplace. Then, tinkering with the rectangular plan, he angled the two side walls toward the room so that more heat was radiated back toward the room's occupants. Finally, he rounded the throat of the fireplace to enhance smoke movement up the chimney.
Deemed the "Rumford fireplace," the resulting design greatly improved the amount of heat felt by the occupants of the room. This creation was almost immediately embraced by the populous upon its publication in "Of Chimney Fireplaces" in 1796, resulting in widespread use of his fireplace and celebrity for Count Rumford.
BIA Rumford Fireplace
The BIA Rumford Fireplace is based on a contemporary version of the original Rumford using currently available materials. While designed to throw more heat back into the room, the BIA Rumford also has the advantage of being a compact, efficiently built masonry fireplace. While most fireplace and chimney assemblies will take at least 1,500 to 2,000 brick to construct, the BIA Rumford only requires around 1,100 brick. This translates not only into a material savings, but also a labor savings since there are less bricks to lay.
Like the original Rumford, the firebox is shallow measuring only 15 inches deep, bringing the back wall closer to the front of the fireplace. The side walls of the firebox are also angled, though not quite as much as on the original Rumford design. By having a less shallow angle for the side walls, there is room to accommodate a modern amenity a small gas log insert if desired. The opening for the fireplace is about three feet wide by 2'3" high. While not rounded like the original Rumford, an eight-inch throat between the top of the fireplace opening and the damper helps contain smoke and prevent it from spilling out into the room. A sloped damper also helps to facilitate smoke movement.
"Eliminating the rounded throat was really an issue of trying to work with available materials," says Clark. "Constructing curved surfaces with a tight radius is difficult without using special brick shapes." In addition, the curved throat was not required by the building code in order to qualify as a Rumford. Consequently, the BIA Rumford Fireplace does not include a rounded throat.
The smoke chamber is assembled from cut pieces of clay flue tile liner. Two 12-inch by 16-inch flue tile liners can be cut on- or off-site. They are then fitted and mortared together on-site to achieve the proper smoke chamber configuration. The damper door is located slightly off-center from the chimney flue with its door swinging toward the back of the assembly. A rotary controlled damper door can be used as an added feature to adjust the damper door when the fireplace is in use.
The chimney is comprised of 12-inch by 16-inch clay flue tile liners. Modular brick surround the flue liner to create a chimney that measures two-feet by 1'8". The compact chimney assembly once again conserves bricks by requiring only nine modular brick for each course.
The specification lays out the sequence of construction and quantities of materials required for the job. If a taller chimney is needed, it stipulates that 81 face brick and one flue tile liner are needed for each additional two feet of height.
Traditional Design Meets Contemporary Options
While a Rumford fireplace is a very simplistic design, the BIA interpretation can be used as a template that can be adapted into alternative styles, such as a freestanding, corner or multi-sided version.
"It could be used in a lot of different ways," Clark explains. "What we show on the BIA web site is just the more traditional approach as a part of an exterior side wall, but it can be easily adapted to meet specific client or design needs."
Finally, the lighter weight and smaller dimensions of the Rumford may also be an added bonus in not only retrofits, but also new construction.
"Large national builders are looking to squeeze every square inch they can get out of a floor plan while providing the features homeowners desire," Clark says. "The smaller footprint and reduced weight are positive aspects for both new contemporary and retrofit construction."
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