EXTERIORS

Fireplaces can be a focal point in a home, and many fireplace options are available when building a new house or renovating an existing home. With those choices, decisions also have to be made about the type and style of that fireplace.

For most people, however, not much thought goes into the chimney. In fact, many homeowners don’t think much about chimneys at all.

“MOST PEOPLE BUILDING A HOME GENERALLY DECIDE ON THE FIREPLACE TYPE, BUT BEYOND THAT, THE CHIMNEY KIND OF DISAPPEARS INTO THE HOME,” SAYS DAN ZIERDEN, MANAGER AT FERGUS HOME & HARDWARE IN FERGUS FALLS. “TYPICALLY, WHEN YOU SAY CHIMNEY, PEOPLE GO BACK TO WHAT THEY ENVISION AS THE BRICK STACK UP ON THE ROOF, BUT TODAY’S FIREPLACES DON’T REQUIRE THAT.”

So, what is a chimney? According to Wikipedia, “A chimney is an architectural ventilation structure made of masonry, clay or metal that isolates hot toxic exhaust bases or smoke produced by a boiler, stove, furnace, incinerator or fireplace from human living areas.”

Zierden says that 50 years ago when fireplaces were used to heat your space, most chimneys were built on the outside of the home, and that was how the smoke was exhausted.

“Fifty years ago, when fireplaces were used to heat your space, most chimneys were built on the outside of the home, and that was how the smoke was exhausted.”

Dan Zierden Fergus Home & Hardware “THAT’S KIND OF FORGOTTEN NOW, AND CHIMNEYS AREN’T AS VISIBLE AS THEY USED TO BE,” HE ADDS. “GAS FIREPLACES DON’T ALWAYS NEED A CHIMNEY, AND VERY FEW FIREPLACES AND CHIMNEYS ARE TOTALLY MADE OUT OF BRICK ANYMORE. FIREPLACE AND CHIMNEY MASONRY IS KIND OF A DYING CRAFT.”

Evidence of stove and fireplace chimneys dates back to the 15th and 16th centuries. Ever since fire was first used indoors, it has always been necessary to find a way to direct the smoke away from the room, and then find a way to eliminate it from the home. In many different shapes and forms over the years, chimneys were developed for that purpose.

As an essential part of the fireplace, the chimney is a way to exhaust the smoke. As the heat from the fire rises up the chimney, it takes the smoke with it.

By drawing the smoke up and out of the room, however, much of the heat has often been taken away along with the smoke, making residential stoves and fireplaces inefficient for many years.

NEW DEVELOPMENTS IN THE PAST 50 YEARS HAVE ALTERED BOTH THE FUNCTIONS AND THE LOOK OF A CHIMNEY. MOST OF TODAY’S CHIMNEYS ARE EFFICIENT, AIR-TIGHT SYSTEMS. WITH A SECONDARY REBURN SYSTEM THAT HEATS THE AIR TO CREATE A CLEANER, MORE COMPLETE BURN CYCLE, THESE SYSTEMS CAN REDUCE HYDROCARBON AND PARTICULATE EMISSIONS.

Depending on the type of materials used, the life of a chimney can go anywhere from 15-60 years. Various types of chimneys include: • Masonry Chimneys • Metal Chimneys • Factory-Built/Prefabricated Chimneys • Fireplace Insert Chimneys • Freestanding Stove Chimneys • Wood-Burning Stove Chimneys

Whatever material it’s made of, the many parts of a chimney work together to keep it safe and efficient. Some parts are necessary, while others are cosmetic.

“Whenever you’re dealing with fire inside the home, there are always risks,” says Zierden. (See Sidebar: Chimney Safety) “You need to be able to maintain clearances and make sure it’s assembled and installed properly. There are certain requirements for air spaces around each chimney product, and different specifications for each one, which vary with every manufacturer. They can be rated differently, and it’s important to find the brand/model/information ahead of time to determine what kinds of clearances are necessary.” CHIMNEY SAFETY

One of the functions of a chimney is to safely carry dangerous gases from a fireplace or wood stove up and out of the home. Most chimney fires start inside the flue, either from a creosote buildup or a flue blockage.

Creosote is a highly flammable, dark brown substance that coats chimney walls when by-products of fire (smoke, vapor, and unburned wood) condense as they move from the hot fireplace or wood stove into the cooler chimney. If the temperature in the chimney flue is high enough, and the creosote build-up is thick enough, creosote can catch fire, so it’s important to keep a chimney properly maintained and free of creosote.

The factory-built metal chimneys must pass special tests, requiring each one to withstand certain high temperatures without sustaining damage. When adding a chimney cap or shroud to hide the pre-fab pipes, however, it’s important to ensure those items are designed around the chimney specifications, and safety tested to the international fire code. “When you install a decorative chimney shroud, and it’s not installed correctly, it can have a restrictive effect and hold the flue gases in place,” warns Derek Lidstrom, president of Chimney King, LLC. “Instead of using ambient air to cool it, the chimney can pull it down one side and up the other, leaking smoke into the chimney chase, turning the wood black, and eventually becoming a fire hazard. I wrote international fire codes for chimneys to help prevent this type of tragedy.”

6 Ways To Stop Chimney Fires Before They Start (from Bob Vila.com) 1. Minimize creosote build-up to prevent chimney fires. 2. Schedule an annual chimney inspection. 3.Clean your chimney when walls have a ⅛-inch layer of build-up. 4.Install a chimney cap (or shroud). 5.Use safe fire starters to avoid unwanted chimney fires. 6.Employ clean burning techniques.

CHIMNEY SHROUDS

The newer chimney systems have metal chimney pipes that exhaust the air out of the roof. They’re not exactly a focal point or design element of a home, and they’re quite different from the old-fashioned masonry chimney – like those envisioned with images of Santa Claus and his reindeer on the roof. “The object on the outside of the top of the house is called a chimney, but it’s really the chimney chase,” explains Derek Lidstrom, president of Chimney King, LLC, which designs and manufactures decorative chimney shrouds. “Most pre-fab fireplaces were not originally designed to be used with shrouds. The first thing a homeowner should ask is, ‘If I’m using a pre-fab fireplace, is it one that allows me to use a shroud to hide the chimney pipe?’”

Lidstrom believes that a good chimney includes these five elements:

1. The fireplace or stove in the home that burns the fuel

2. A chimney flue pipe (terra cotta or round metal) to get the smoke out of the room

3. A good, strong main chimney chase, which the smoke goes through (can be finished in brick, stone, stucco, or most commonly, siding)

4. Top-of-chimney waterproofing treatment and cornice detail, which the pipe goes through (usually concrete or metal)

5. A decorative chimney cap or shroud (to hide the pipes sticking out of the top) to improve drafting, and keep out rain and critters, but mainly to give the home a polished roofline appearance

“It takes some planning to safely add a shroud to cover the ‘nonattractive’ pipes on your roof.”

Derek Lidstrom

Chimney King, LLC “PREFAB CHIMNEYS REQUIRE A 2-INCH CLEARANCE TO COMBUSTIBLES IF NO DECORATIVE CHIMNEY CAP IS USED,” SAYS LIDSTROM. “IF YOU WANT SOMETHING TO HIDE THE PIPE, IT TYPICALLY REQUIRES A 40 PERCENT LARGER CHASE TOP, SO NEW DIMENSIONS NEED TO BE CONSIDERED DURING THE DESIGN PHASE.”

Most fireplace stores haven’t been in the business of selling chimney caps, he says. When prefab chimneys were first introduced, it wasn’t technically legal to add any kind of chimney cap to those systems. Chimney King has been in business since 1992, and Lidstrom has worked closely with the international fire codes to ensure that any chimney caps or shrouds that are added to these systems are done properly, meet the codes, prevent fires, and are also attractive .

“It takes some planning to safely add a shroud to cover the ‘non-attractive’ pipes on your roof,” says Lidstrom. “The market is correcting, and we now have more than 150 styles to choose from, covering every material and color you can imagine. Most chimneys are not as beautiful as they could have been – we want to bring back the beauty.” L&H