Chimneys & Chimney Cleaning Tips

If you have a fireplace that burns wood for fuel, then the chimney is a very important component of your home; one that deserves regular attention and maintenance in order to ensure it’s heating efficiency, structural integrity and safety.

One of the primary functions of the chimney is to properly exhaust fumes and particulates containing harmful, poisonous gases; if your chimney does not draw or vent properly, not only will the normally soothing fragrance of a wood fire become overwhelming, it can present potentially serious health concerns if not addressed!

Common sense tells us that wood fire particulates, creosote and soot build up inside the chimney, but we often neglect to count the number of fires burned inside the firebox since the last time the chimney was inspected or cleaned!

A chimney that normally draws fine, but begins to emit strong fumes inside the living space, is often a sign that the chimney has built up excessive creosote and soot inside. Do not wait to have a look or cal in a professional anytime you smell a strong odor of wood smoke coming from any fireplace.

Chimney Structure and Components

A fireplace chimney is a relatively complex system; structure, size, diameter and other factors will determine how well it draws, providing a steady fire in the firebox and expelling the harmful gases produced by combustion.

Traditionally, most wood-burning fireplaces were built using masonry materials such as bricks and mortar and surrounded with tile or stone. Today, many fireplaces are prefabricated for easy installation, without the need for an expensive masonry chimney foundation and structure.

Built using a stud-framed metal flue, these modern fireplace units are much easier and affordable to install in new homes or fireplace retrofits. They also are not susceptible to structural damage in an earthquake, making them very popular in the western states.

There are several components most wood-burning fireplace chimneys have in common:

Chimney Flue and Liner – The flue of a fireplace is an inner layer that allows hot air and gases to rise from the firebox and effectively vent up through the roof. It must be lined properly and kept free of debris and creosote to allow proper venting.

Chimney Damper – The damper allows you to close up the fireplace chimney when not in use, keeping out unwanted moisture and cold air. Typically, the chimney damper will be a metal spring door near the top of the chimney. A long metal rod or chain lets you open and close the damper; many of us have made the embarrassing mistake of starting a fire with the flue closed, so be sure yours is easy to check whether it is in the open or closed position!

Chimney Cap – The chimney cap or chimney cover prevents downdrafts and protects the chimney from rain, snow, pests, etc. from entering the chimney. In some cases a cowl or helmet-shaped, wind directional chimney cap is installed. The cowl is designed to rotate with the changing wind direction and help keep smoke from being blown back down into the chimney.

Chimney Flashing – A chimney must be adequately flashed where it extends through the roof to prevent moisture from getting under the roofing material.

Firebox Cleanout Door – An ash pit at the base of a chimney is typically covered with a metal door to make removal of ashes easier; remember that ashes from a wood-burning fireplace may remain hot for a very long period, even if you do not have a fire for some time!

Wood-burning Fireplace Operation

The type of wood you burn will affect how often your chimney needs inspection and cleaning; pine for instance leaves more residue than slower burning types of wood such as oak.

Masonry chimneys can suffer cracking and fatigue over time. "Spalling" is a problem that can occur when moisture seeps into a brick chimney and freezes, causing the mortar seals to flake, crack or come loose.

Especially if you have an older masonry chimney, seek the advice of a professionally trained, certified chimney expert if you have any doubts whatsoever about the condition of your chimney! This is often a topic of discussion in the sale of homes having older masonry chimneys.

Types of Chimney Liners

Most chimney liners are made using clay, metal or concrete. Each type has specific pros and cons, depending on the type of chimney and other factors:

Clay Chimney Liner – Clay is popular due to lower cost, durability and effectiveness. A clay liner can last as long as 80 years and works well on an open fireplace chimney. One disadvantage of clay chimney liners is that ceramic tiles can crack or split if a chimney fire does occur; in this case they will likely need to be repaired before you can use the fireplace again. Clay also is not suitable for a gas fireplace as the liner will not adequately contain the combustion byproducts of a gas flame.

Metal Chimney Liner – A liner made of stainless steel or aluminum is commonly used these days when repairing or upgrading an older chimney. Stainless steel is a good option with fireplaces that burn wood, gas or oil; aluminum is only suitable in some cases. Metal liners are not used for open fireplace chimneys and must be insulated properly for safety and performance reasons.

Concrete Chimney Liner – A concrete or cast-in-place chimney liner is also used sometimes. A special heat resistant concrete is poured inside the chimney to form a vent path for rising smoke and gases to escape. Concrete liners may be used to strengthen older chimneys and can be used with most fireplaces and fuel types. The primary disadvantage is that a concrete liner is permanent and requires demolition should it need to be replaced!

Home Fireplace Tips and Precautions

  • Test a new fireplace and chimney by lighting a few small fires; don’t build a raging bonfire in your new fireplace until you are sure it drafts well and the mortar has cured.
  • Use well seasoned wood in your fireplace; wet wood that is still green only causes a more rapid buildup of creosote in the chimney.
  • Never leave an untended fire in your fireplace.
  • Close the damper as much as possible without impeding good draft; the slower your fire burns, the less wood you burn and the more heat you enjoy inside the house!
  • Too much creosote buildup in your chimney can cause a fire to ignite inside the flue; not only is it embossing to have the neighbors see flames shooting up out of your chimney and call the fire department, but this is a very dangerous situation which can cause a home fire! Cracks in masonry chimneys or corrosion in metal flues can also result in a home catching fire.
  • Install carbon monoxide sensors in your home; this is the only way to be sure your family is safe from potentially harmful gases a poorly drafted fireplace can cause.
  • Only the heartiest and most seasoned do-it-yourselfer should attempt to perform fireplace and chimney inspection and cleaning; unless you really know what you’re doing, leave this one to the experts!

How to Inspect and Clean a Fireplace Chimney

If you are prepared to get real dirty, you can make your own periodic chimney inspection. A good compromise might be to hire a professional to inspect every fall before the cold weather comes and then inspect and clean it again yourself in the spring to determine if a second cleaning or other repaired may be needed so that you can rest easy if you still like to have a fire once in a while during the warmer months!

Tools and materials you’ll need to inspect and clean your chimney:

  • A steel chimney-sweeping brush or very stiff brush; the type sold at home centers for acid washing and such
  • A heavy duty shop vac
  • A drop cloth or cardboard to protect the hearth and area around the fireplace
  • A length of PVC pipe the same diameter as the shop vac hose to extend down the flue
  • Sealant and nails or screws to reattach the chimney cap if it is removed
  • A Ladder tall enough for safe access to the roof
  • A Flashlight (or several)
  • Safety goggles or other protective eyewear and a good pair of work gloves you don’t mind ruining.
  • A desire to fit into tight spaces and walk away covered with thick, black soot!

Get ready to get dirty and remember; inspecting and casually cleaning your fireplace chimney is not a substitute for having it done professionally. Don’t do this project the morning after you have had a fire in your fireplace; give things some time to cool off first! Put down plenty of drop cloths and/or some cardboard to keep your hearth and flooring clean. Here we go:

  1. Start by taking out the andirons (if not attached) and removing the ashes and loose debris from the firebox, using the chimney brush to clean the sides and bottom.
  2. Time to make a visual inspection; put on your safety goggles and, with the firescreen out of the way and fireplace louvers or glass doors as wide open as possible, lie on your back and slide your head into the firebox (again not if it’s very warm in there!) and shine a flashlight up into the flue. Look for any signs of masonry cracks or problem areas if your flue and/or insert are made of metal.
  3. Get a helper to open and close the flue so you can check it for good and secure operation; the damper should not be loose or have excessive soot or creosote coating. Leave the flue in the closed position when inspection is complete.
  4. Put a large piece of cardboard down in your firebox with one edge folded up at the front of the fireplace opening and close the glass doors or otherwise close up the fireplace opening for this next step; its time to climb on the roof!
  5. If the chimney has a cap or cowl covering the top, you’ll need to remove this first; be sure you have the flashing and/or hardware needed to close it back up afterward.
  6. Use your flashlight to look down into the flue; as you did from the bottom, you’ll be looking for a build up of creosote and soot, as well as any cracks or problem areas inside the flue.
  7. Unless you have a proper chimney brush, about all you can do is use your steel brush to clean the inside of the flue as far down as you can reach; this is not the right way to clean the chimney so don’t fool yourself into thinking you’ve accomplished much without the right equipment and skills; complete chimney cleaning and sweeping are outside the scope of this article.
  8. You can use a length of PVC pipe to extend your shop vac hose so that it reaches down into the flue; you want to be sure you remove the debris that will have fallen from the sides of the flue. The damper door and smoke shelf will catch most of the debris and keep it from falling all the way to the floor of the firebox.
  9. After cleaning, shine your flashlight down into the flue and inspect everything again; it will be easier to spot any problems now that you have cleaned the inside of the flue!
  10. Put the chimney cap back into place; replacing the flashing if it is corroded to be sure things are well waterproofed.
  11. Once you are done on the roof, its time to go back down to the fireplace; vacuum up the loose ash and debris before removing the cardboard and drop cloths carefully to keep ash and soot from ruining carpeting or scattering everywhere!

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