A chimney is susceptible to a AT number of problems, ranging from the buildup of flammable deposits in the flue to damaged and leaking masonry. Serious damage requires repair by a professional mason. Homeowners willing to get up on the roof can handle basic inspection, repairs, and minor improvements. This section shows the basic steps for inspecting your chimney to keep it in safe working order and some improvements to make future maintenance procedures simple.
Tools: Rope, tuckpointing tools, mason’s trowel.
Understand chimney anatomy. The firebox has splayed sides that serve to pull air across the hearth to the base of the fire. The sloping upper rear wall of the firebox deflects heat back into the room. At the top of the firebox, the throat pulls smoke up into the flue. A damper there allows you to control the draft and close the flue when the fireplace is not in use. Higher up the chimney, a smoke shelf stops cold air from coming down the flue and diverts it back up the flue. Without the smoke shelf, cold air from the outside would drop down and push smoke into the living area. Many fireplaces have an ash door, plus an ash pit and a cleanout door, allowing you to remove your ashes from the outside of the house. Some ash pits have an air vent to create a better draft.
Caution! An Ounce of Prevention -
■ If your fireplace chimney becomes caked with flammable deposits, you could have a flue fire. This is extremely dangerous; the heat is intense, and the fire is difficult to put out. A flue fire can possibly even lead to a house fire. So be sure your chimney is clean before you light a fire.
■ If your fireplace has not been used for a while, have it examined by a professional who specializes in chimneys.
■ Your chimney often is connected to the framing of your house. The weight of a damaged chimney can lead to serious structural problems. If you suspect severe damage, call in a professional.
Inspect your upper chimney. The part of your chimney that is exposed to weather is the most likely to fail. Inspect it thoroughly for crumbling bricks and mortar. (Your chimney may not look quite like the drawing above; it may be all brick, for instance.) Replace broken bricks and tuckpoint them if necessary. Make sure the chimney cap overhangs the brick. Check for loose or missing flashing.
Make a new chimney cap. Chimney caps often are constructed incorrectly so they don’t protect the bricks from water damage. Shown here is a design for a cap you can pour in place. Hold the form in place with a few masonry nails and remove it after the concrete has set. When finishing the concrete, be sure to slope it away from the flue so water can run off easily.
An Annual Checkup - Every year, make a quick inspection of your chimney. Look at the following:
■ See if any tree branches are within 10 feet of the chimney. Trim off the branches if they are; they can cause draw problems and create fire hazards.
■ Check to see that the damper and its controls work smoothly. Use a flashlight to see if it opens and closes completely.
■ Check the draw. When you light a fire, the smoke should rise easily and not flow into your living area.
■ Clean out ashes that have accumulated in the ash pit.
■ On the roof and in the attic, check the chimney bricks and repair any damaged areas.
1. To clean a fireplace chimney, seal off the inside opening. Cleaning produces a great deal of hard-to-vacuum soot, so make sure it cannot enter your home. Firmly tape a wet sheet or a piece of heavy polyethylene sheeting to the opening. Check that there are no cracks for soot to seep through.
2. Make a "brush." You can rent or buy a regular chimney brush with extensions for reaching down your chimney. Or, make a cleaning tool out of a piece of canvas and a rope. Wrap chains or pieces of broken bricks in the canvas, tie a rope to it, and lower it into the flue.
3. Sweep the flue. Move your “brush” vigorously up and down in the flue, slowly moving downward as you work. Lower the brush all the way down to the damper, pull it up, and repeat the process until you no longer hear caked deposits being dislodged from the flue.
Install a screen cap. Here is an easy way to keep birds and squirrels out of your chimney, and protect the inside from water damage. Measure the outside dimensions of your flue and purchase a screen cap to fit it. Installation is simple—place it on top of the flue and tighten the hold-down screws.
Gas Fired Units
■ If your old chimney is not safe for wood-burning fires, before you install a gas unit make sure it poses no structural dangers. Make any needed repairs to ensure it will not collapse and will not compromise the framing.
■ If you want to have a fire in your fireplace without replacing the entire chimney, consider installing a gas-fired unit. This needs little or no venting, so it does not matter if your chimney draws poorly. Though it’s not a wood-burning fireplace, it does have advantages: You don’t have to haul and store logs, it’s easy to start, and many slide-in models have heat-circulating systems that efficiently heat your home.