Home Inspection - Chimneys. http://www.homeownerseries.com
An often-overlooked structure in a home is the Chimney and Fireplace. Chimneys are built to vent smoke from fireplaces and from heating units, such as coal burning heaters. The fireplace is usually located in the family room or living room of the house and may be either wood burning or gas burning. Chimneys are usually made of brick, cement block, stone, and concrete. Alternative chimney styles utilize metal and are often found in buildings where large masonry chimneys are not practical.
Major Chimney parts are as follows: the Spark Arrestor or Chimney Cap, which is located on the top of the chimney (all chimneys should have a spark arrestor on the top of the flue. This is to prevent sparks from leaving the chimney and starting a fire away from the home. The spark arrestor is usually a metal grate that also has a metal rain cover); the flue, which is the main body of the chimney; the damper, which opens and closes, allowing access to the flue; the firebox, which is where the fire takes place; the hearth and the front façade, which is usually made up of brick or stone.
Chimneys, as a structure, are normally supported on their own foundation, resting independently from the house. The chimney foundation may however, be attached to the foundation of the home, but it is not necessary. The top of the chimney must extend above the roofline as to prevent downdrafts caused by the wind as it sweeps over the roof. It should stand three feet over a flat roof, and two feet over a pitched roof. The top of the masonry stack should have a cement finish that slopes away from the flue. This is to direct water away from the flue and the joints between the flue and the chimney.
Due to their independence from the main structure of the house, chimneys with their own foundation may settle in opposition to the home, causing the chimney to pull away from the home slightly. This is not usually a major problem if the lean is minor, however, the openings must be sealed or flashed to prevent the outside weather from affecting the interior of the structure. Excessive lean brings about structural safety concerns, a matter that must be evaluated and remedied by a structural engineer.
Make sure that the chimney is properly flashed, in any case, to prevent water from getting into the house. This includes the installation of a cricket or saddle behind the chimney to prevent snow buildup and water damage. Make sure that the firebox has an adequate screen or glass front to keep sparks inside the firebox, which helps prevent fires outside of the fireplace.
The corrosive gases from fires inside the fireplace deteriorate the mortar joints of the bricks in the chimney. This may lead to openings that could facilitate a fire hazard in the house.
All chimneys should be lined with one of three types of liners: concrete, stainless steel, or aluminum. If you have an older chimney that is not lined, consult a local heating contractor for your specific needs.
In examining the firebox it is important to check the bricks or stones for cracks, and chips. See if there is any broken or disintegrating firebrick and that the mortar joints are tight with all mortar in place. Look at the damper in the firebox; check that it operates properly and can close tightly when not in use and open widely when the fireplace is in use. Look for a build up of soot and creosote the by-products of burning a fire; if the build-up is heavy then it needs to be cleaned. Excessive build-up may lead to a chimney fire, which is very dangerous and usually ends up causing a house fire. Look for any obstructions in the chimney, which would keep it from functioning properly. Some fireplaces have gas logs installed. Check to make sure that they are placed well into the firebox. Check that the gas valve opens and seals completely when closed.
If your chimney is used more than three times a week, it should be inspected at least once a year. If you have any concerns about the safety of your fireplace, stop using it and have it inspected by a licensed professional.
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