FIREPLACES & CHIMNEYS

FIREPLACES & CHIMNEYS
February 4, 2011 Gregory F. Shue II

This article by Greg Shue first appeared in the Winter 2006-2007 edition of Design Lines magazine, a periodical published by the American Institute of Building Designers.

Figure 1

Figure 1: http://bia.org/bia/technotes/t19.htm

Ever since people have lived indoors with fire, there has been a need to exhaust the smoke and protect the dwelling and inhabitants from uncontrolled flames. Whether for cooking, heat or light, fire has been a useful resource to harness indoors not only for those tangible aspects, but also as a desirable element that brings coziness and intimacy to interior and exterior spaces. Over time, many different methods have been developed for creating and harnessing fire, and they have all been adapted to the nearly infinite variety of interior design styles.

Figure 2

Figure 2: www.rumford.com/classicphoto.html

For about 790,000 years, mankind has harnessed the power of fire. Since then, cooking over a fire has been the primary method of food preparation, people have warmed themselves by fires as a primary source of heat, and light from fire has been the primary source of light at night (until the relatively recent inventions of other means to accomplish all these goals). Cooking, heat, and light have all been readily accessible with the use of fireplaces and chimneys. The primary downfall of an indoor fireplace is the potential accumulation of toxic gases if not vented properly to the outdoors, however, the invention and refinement of the chimney has enabled people to enjoy the benefits of fireplaces for millennia.

Figure 3

Figure 3: www.brynmawr.edu/iconog/ajnls/kdet 07.jpg

Today, there are typically two types of masonry fireplaces (masonry being the most established reliable material for the control of fire to confined areas),the standard firebox and the Rumford firebox. Either of these can work easily in conjunction with a hearth (the nonflammable extension of the firebox into the room, which protects the floors and furnishings from errant coals and embers- raised above the floor or at floor level). Standard fireboxes tend to be the shorter, wider, and deeper of the two (Figure 1). Rumford fireboxes tend to be taller and less deep. Most masons are familiar with the traditional masonry configuration of standard fireboxes, while Rumford fireboxes (Figure 2) tend to have specialized pieces (developed by Count Rumford around 1793). Regardless of the firebox design, mantels can be designed or purchased to match the architectural theme (Figure 3). Local building codes regulate the proximity of flammable materials, so the common practice of providing a non-flammable surround to the firebox has been established, which is usually bordered by a decorative frame and mantel. In lieu of these more traditional arrangements, fireplaces have been built successfully that have more unusual configurations, such as a see-through firebox that serves two rooms, a firebox that is exposed on three sides, and myriad more, including manufactured fireplaces.

Figure 4

Figure 4: http://en.wikipedia.org/wiki/Image:Th ornbury.chimney.detail.arp.750pix.jpg

Not only are there choices for basic layout, but there are many choices of fuel to maintain a fire. In the recent past, gas plumbing has made natural gas and liquid propane very popular options for primary source of flame and also as starters for wood fires. Depending on the arrangement and special requirements, coal, gel and alcohol can also be used to maintain a fire in the firebox.

Figure 5

Figure 5: http://en.wikipedia.org/wiki/Image:Chimney.stack.london.arp.jpg

Chimneys are the top-most extent of the flue, which carries the smoke away from enclosed interior spaces. Like the firebox, surround and mantel, chimneys can be styled to add visual interest at the top of buildings by matching the vocabulary of the building below (Figure 4). Chimneys are made up of various parts, many of which are rarely, if ever, seen. The damper is located at the top of the
firebox; it opens and closes to regulate the amount of air going up the flue. The flue is the fireproof chase that delivers the smoke from the firebox below to the top of the chimney above. Flues are usually made from clay tile or insulated metal ducts, in which case flues may not have the same building code requirements to be primarily vertical (especially if fans, or draft inducers, are used to force air and smoke through the duct). At the top of the chimney, decorative elements are commonly used to visually terminate the vertical chase, such as chimney pots (Figure 5) and chimney caps (Figure 6). The choice of which, if any, are used generally depends on the style of the exterior of the building.

Figure 6

Figure 6

All in all, the value that fireplaces add to an interior space makes them important design elements. There are endless options available to the designer to seamlessly integrate fireplaces into the interior and exterior of buildings. With further investigation into the requirements of local building departments and careful consideration how they affect design intent, designers and end users can both feel rewarded by the successful execution of beautiful and useful fireplaces and chimneys.

For more information, consider these resources:
1. Your local building code;
2. The Brick Institute of America.