HomeownerEducational: A-M

Chimneys & Fireplaces

Chimneys & Fireplaces

Chimney Cleaning Overview

The purpose of a chimney cleaning is to remove any creosote, animal nesting materials, and other flammable debris that has accumulated in the chimney. A chimney sweep will use a variety of tools, such as vacuum cleaners and wire brushes, to remove debris and make the inspection process easier.

The National Fireplace Institute (NFI) and the Chimney Safety Institute of America (CSIA) recommend that a chimney be inspected annually and swept as necessary, or when the creosote reaches one-eighth of an inch of buildup. Creosote is highly flammable, and a chimney fire burns very hot; its flames can extend ten feet above the top of the chimney. Chimney fires can quickly spread to the roof, the attic, or other wood around the chimney and destroy the entire house. If a chimney fire starts, first get everyone out of the house as quickly as possible, and then call 911.

Chimney Inspections

The National Fire Protection Association (NFPA) designates three levels of chimney inspection:

Level one inspection. This basic inspection is recommended if nothing about your chimney has changed since the last inspection. The technician should inspect the accessible portions of the chimney’s interior and exterior as well as the chimney connection. He or she should also make sure that the chimney is free of obstructions and combustible material.

Level two inspection. A level two inspection is required when any changes have been made to the chimney, fireplace, or their use since the last inspection. It is also required if the property has changed possession since the last inspection or if the structural integrity of the chimney has been compromised (for example, from a fire or tornado). It should include everything in a level one inspection plus an examination of every accessible portion of the chimney’s exterior and interior. A level two inspection should also include a visual inspection of the chimney’s interior, generally accomplished by a video scan.

Level three inspection. The most drastic of the three types, a level three inspection is only necessary when serious hazards are suspected. It should include everything present in a level two inspection as well as some demolition as needed in order to fully inspect questionable areas.

Limiting Creosote Buildup

The byproduct of burning wood is creosote, or soot. It’s essentially unburned fuel formed when flue gases are too cool and condense into a grimy buildup. As the creosote and smoke travel up the chimney, some of the highly flammable creosote is deposited on the insides of the chimney, and over time, the buildup can create a chimney fire hazard. One way to limit the amount of creosote in your flue is to make sure you have enough airflow in the home. As the air in the chimney moves up and out into the atmosphere, it needs air brought in to replace it. Before homeowners began sealing up their homes with insulation and caulk, air infiltration was common and chimneys drew beautifully. As a house is sealed up, less air gets in, and the flue gases vent more slowly. They cool and condense, resulting in more creosote.

Beyond ensuring that your fireplace and chimney receive sufficient airflow, only burn dry, seasoned firewood. Fresh, damp logs contain moisture that will cause the fire to smolder, releasing combustible gases that contribute to creosote buildup. Split whole logs in halves or quarters to make sure the wood is completely dry, both inside and outside.

Chimney Cap

The chimney cap is a device usually made of stainless steel or copper, which is used to protect the chimney from invasion by pests and rain. The warmth and shelter provided by uncapped chimneys can attract birds, squirrels, raccoons, and other furry pests who may nest in the chimney space. This can lead to fleas and unpleasant odors, and the presence of the nesting materials poses a fire hazard. Another advantage of the chimney cap is that it also shields the top of the chimney from ice accumulations and keeps rainwater out of the flue, extending its life. Chimney caps are important because they contain larger fire sparks within the chimney and keep stray embers from igniting the roof or flying down into the yard.

In particular, metal chimneys need to have a chimney cap. Metal chimneys are fabricated with two or three layers of metal with insulation placed between each; a chimney cap prevents water and moisture from accumulating between the layers, reducing the chance for premature failure of the chimney. Many different types of chimney caps are on the market: stainless steel, copper, crown mount, multi-flue, cap/damper combination, and various others. To determine the best type of cap, a homeowner should consult a professional.

Chimney Repair Work

Minor repairs. In clearing away creosote and debris from your chimney, a chimney sweep may alert you to areas that need repair. Some companies that clean chimneys will also fix small problems with the chimney or firebox, such as repairing or replacing a broken damper or chimney cap. If you want your chimney cleaned and inspected, choose a company that provides both of those services. You can also keep an eye out for possible problems by checking the exterior of your chimney for signs of damage.

Masonry repairs. Most chimney companies employ bricklayers to restore sections of a chimney that are deteriorating. Bricks that are spalling or missing can be replaced; cracked or crumbling mortar can be re-pointed; and gas valves that are embedded in the masonry can also be replaced. If the damage is beyond repair, the bricklayers can rebuild either a portion or all of the chimney.

Leaning chimneys. If a chimney begins to lean away from the house, a professional should be consulted to identify the source of the problem. Depending on the cause and severity of the lean, the chimney may need to be rebuilt or be reinforced by steel piers in the ground.

Liner replacement. Chimney liners provide necessary protection from heat and combustible materials. In most cases, masonry chimneys have terra-cotta liners. Initial building defects, damage, or deterioration over time may warrant chimney liner replacement. Flue sealant products and stainless steel liners are used to repair or replace the liners.

Chimney Service Companies

Chimney cleaning is a very seasonal business, and winter is typically the busiest time of the year. Since scheduling an appointment can be difficult in winter, plan on getting a chimney cleaned in the off-season. A professional can easily spot small problems and maintenance issues before they turn into huge repair bills or safety issues that could potentially put your entire home in jeopardy.