Frequently Asked Questions about Chimney Services

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Below are some of the most frequently asked questions that we hear from our clients. We hope that this section will help you make the right decision regarding the proper maintenance of your chimney. If you have any other questions or would like to inquire further about our services, contact us today.


Why doesn’t Carleton Chimney clean chimneys anymore?

We decided in 2006 to stop cleaning chimneys and focus our business on the restoration and repair side of the business. This allowed other sweeping companies to refer us for the repair and not worry that they would lose the cleaning business in the future. It also allowed us to educate sweeps on hazards that need to be documented and to give proper warning to users.


What does "WETT" stand for?

It stands for Wood Energy Technical Training. Currently the only recognized training available is through Wood Energy Technology Transfer. There are multiple courses available and the insurance industry and building officials recognize this certification. It is the only assurance the public has that the person doing the work has been given some formal training. Please read more about WETT inspections in our services page.

eroded chimney

I have a white powder growing on my chimney. What is this?

The white, chalky-looking growth is called efflorescence and is caused from excessive water getting into the masonry. The water washes the salts out of the masonry and they condense on the exterior brick. This will cause extensive damage to the brick and will likely cause mold and mildew growth in the walls behind the chimney. It is important to identify the source of the water and correct the issue. See a sample picture of this condition.


Why do I sometimes smell creosote in my home, especially on damp days?

This is sometimes referred to as a downdraft, but is more accurately known as a negative-pressure situation; it is the result of air wanting to come down the chimney rather than go up. This is most often the result of the home having too many appliances that remove air from the house and not enough air coming back into the home to replace it. The fireplace is an easy access point for air to enter back into the home. A negative-pressure situation will often cause smoke to be pulled down into the basement when the main floor fireplace is used. The answer is to give the home an alternative source for air and to reduce the amount of air that is being removed.


As an experiment, open a basement window, preferably on the north or west side of the home. If the amount of cold air coming down the chimney is reduced, you likely have a negative-pressure problem. Installing a fresh air supply will likely remedy this. There are other reasons for this to happen that require an experienced technician to test for.


My insurance company has told me I need to have a WETT Certificate for my installation. What is this?

There is no such thing as a WETT certificate, but there are WETT inspections. The first level of inspection looks at visible components to determine compliance with the Ontario Building Code, B365 and the installation instructions for the appliance. If defects or suspicion of defects exist, it may be necessary to go to a higher level of inspection, which may require opening walls or dismantling parts of the system.

old chimney

Why should I rebuild my chimney to the roof level when the damage is only at the top?

Damage to a chimney is the result of water entering the brick and then going through repeated freeze/thaw cycles. This damage happens in any unheated area and is not always visible to the naked eye. If the chimney is more than 25 years old and is showing brick damage, it is wise to rebuild the chimney to the roof level. See the sample picture of a chimney that was rebuilt partially and how it looks after only 3 years.


I have an older home and my fireplace works quite well. Why do I need to have it inspected when it works so well?

Homes built prior to 1954 did not typically have a liner inside the flue. The mortar was strong and the fireplaces were used regularly so as to keep moisture out; today’s owners use their fireplaces sparingly. Moisture can enter the masonry, causing it to deteriorate and fall out and leave a hole where heat and gasses can enter into the living spaces of the home, potentially leading to a house fire. Just because a fireplace performs well, does not mean that there isn’t a deficiency that could cause a catastrophic event.


I am considering having my fireplace re-faced so as to modernize the appearance. Are there any special considerations?

It is common for some home owners to hire a cabinet maker and/or tile setter to re-face the fireplace. While these trades are good at what they do, they may not understand Codes regarding the fireplace. It is common for us to come into a home after the alteration is done, only to find that it has a serious infraction that can affect safety. It is wise to at least have a consultation to ensure that your plans for the fireplace will not contravene any safety Code.


Why does Carleton Chimney Services Inc. charge for an estimate? I can get a free estimate from others.

We do not provide estimates but rather conduct assessments of the chimney and fireplace system. This includes a definite appointment time, an inspection of all visible components by a certified WETT technician, a written technical report and prices for the repairs. If options are available to you, we will discuss these even if it is work we do not do. Our assessment fee allows us the time to do a proper analysis of your system. Most companies that offer free estimates will come at their convenience, report on only the area that was asked about and give either a verbal quote or a price without a proper breakdown. You may be told on completion that there are other problems that need to be repaired at a further cost. Having a proper assessment ensures that surprises are rare and that your decision on repairs is made with full disclosure of the situation.

dirty chimney

I have a metal chimney, so there should be no concerns. Right?

Depending on the vintage of your chimney, you may have a significant problem. The earlier versions of factory-built chimneys contain an insulation that can attack the casing and erode right through it. Even if the chimney looks alright, it should be inspected for signs of this problem that may not be visible to you.


What is the difference in rebuilding the chimney and pointing the chimney?

The life expectancy of a chimney above the roof is approximately 40 to 50 years. It is common at this age for the mortar to have softened and fallen out and for the brick to begin to flake off. Rebuilding requires dismantling the chimney down to the roof and rebuilding with all new material. Pointing is simply taking out the mortar for a depth of approximately 1” deep and “tucking” new mortar between the bricks. If done properly, the repair can last as long as 10 years. If there is any damage to the brick, the repair will not be complete and will not last. It is rare that pointing a chimney is the sensible way to do a repair.


When I use my upper fireplace, I get smoke in the basement. What causes this?

This is called smoke migration and can be caused from one or more causes. In a newer home, it is likely due to negative pressure in the basement, where the air has risen to allow the fireplace on the upper floor to draw the smoke out. As the smoke exits the top of the chimney, it is pulled back down the basement flue in an attempt to equalize the pressure in the home. If this condition exists, it is common to feel cold air coming from the basement fireplace all the time. The other problem could be a poor seal between the flues. There should be 3 different seals to prevent this but it is common for the seals to be done so poorly as to allow the smoke to leak. The danger here is that heat can leak behind the walls into the framing of the house. Visit CeCURE flue repair for a repair option.


I am a property manager and have a development with many fireplaces. Should I have them inspected?

Multiple-unit residences pose a particular safety concern in that the chimneys often pass through other units or are adjoined. It is common to have the factory-built metal chimney systems in these units, and they have proven to be a safety concern. We will come in and advise you as to a course of action after a short review of the site. This is more economical than having all the chimneys cleaned when there may be problems that render them unsuitable for use.

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