This May Be Why Your Fireplace Smokes in the Home

by on January 8th, 2011
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I don’t know about you but I love to come in from a cold day outside and back up to a hot fireplace. The dancing flames and hot coals cut the chill and give a sense of old time cheer and comfort. But it can be a real hassle if your fireplaces smokes into the home. I recently talked with a lady who had a smoking fireplace problem. I grew up in construction before becoming a contractor and worked with quality bricklayers building fireplaces for many of our homes. If you’ve never seen a properly constructed fireplace you might not know what to look for. Here are a few reasons why your fireplace may smoke and what I did to help this lady cure her smoking fireplace.

The home in question is a very nice rock faced building more than 40 years old. The fireplace was faced in ledge stone with a flagstone hearth. A nicely shaped with rear ash pit and metal damper was laid up with fire brick. The original owner had installed a cast iron fireplace insert in an attempt to correct smoke backing up into the house. I don’t know other solutions the original owner tried, but they eventually gave up using the fireplace. The second owner, the lady, also couldn’t use the fireplace for 13 years before asking me to investigate.

Fireplace smoke backs up into a home because the chimney does not draw properly. A few reasons why this may happen are:

Chimney obstructed

If your fireplace worked before but now smokes you may have an obstruction. This is easy to correct. Birds often build nests in chimneys. Take a look, clean it out.

Damper closed

I’ve done this before, so I know it’s easy to do. Open the damper.

Fire not hot enough

You need hot air rising within the chimney to create a draft–what we call draw. Start the fire with dry kindling. You can add wet or green wood after you have some good coals. Some people hold a burning newspaper up to the damper to help start the draft, but this shouldn’t be necessary.

Air pressure differential

Modern homes are quite tight and may not provide enough ventilation for a fireplace. Open a window or otherwise provide air to the fireplace for combustion and draft. A central heating system may cause problems by drawing air down the chimney when a fire is present. Rare, but it does happen.

Chimney not high enough

The chimney should be at least three feet above the roof within 10 feet. This is a general rule. Air patterns and wind can cause problems at different times.

Improperly constructed fireplace.

I add this because this is the problem with the 40 year smoking fireplace. Remember that the initial inspection of the fireplace was good. Outward appearance showed a well constructed fireplace. When I climbed up on the roof to inspect the chimney I found–no chimney. Only the outside of the fireplace had been laid up to proper height. No flue had ever been installed. The opening was two feet by six feet from the damper all the way up. It would be impossible for anything but a roaring bonfire to heat that space enough to create a draw.

The solution is to install a flue or appropriate chimney. Since a high quality cast iron insert had been installed I added a class A stainless steel chimney and capped the rock “chimney” with heavy duty galvanized sheet metal. It’s hard to believe this problem went unsolved for more than 40 years.

More from Gerald:

Spring is a Great Time for Exterior House Painting

For the Home Toolbox: Wood Chisels

Solar Heating With Aluminum Soda Cans

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