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The Journal Gazette

Saturday, October 07, 2017 1:00 am

Get chimney cleaned, inspected then fix it

James Dulley

Dear Jim: We use our wood-burning fireplace for heat. It has not been cleaned out for years and we noticed bad spots on the outdoor chimney brick. What maintenance steps can we do ourselves? – Michelle B.

Dear Michelle: There are some maintenance items you can do yourself, but you must first have the chimney flue professionally cleaned by a chimney sweep. A cleaning also includes a complete inspection. Thousands of homes burn to the ground each year from chimney fires.

The bad outdoor spots on the chimney should be checked, but are not as serious as issues inside the chimney.

The most common problem is creosote deposits from too little combustion air or burning too much unseasoned firewood. Creosote is extremely flammable when it gets hot inside the chimney.

When there is a creosote fire in the chimney, even a small fire, it can damage the mortar and break some tiles. If cracked tiles fall across the flue and block the air, this causes heavy smoke back drafting. You will definitely notice this if it happens.

A more serious problem is the slow deterioration of the mortar between the chimney tiles from repeated smaller fires. This can allow the fire itself or just the intense heat to penetrate the chimney and start the wall framing on fire. Wall framing may be burning for quite a while before you notice it. If you are sleeping and don't have smoke detectors, this can be catastrophic.

Another sign that there is creosote buildup and there have been some chimney fires is puffy black pieces that fall into the fireplace. Creosote is a hard material when cold, but when it burns, it puffs up and feels somewhat like chunks of black polystyrene foam. It crumbles very easily when it is touched.

When the chimney sweep runs brushes up and down inside the chimney, it will definitely knock the puffed creosote loose if there has been a fire. When the cleaning is done, the entire length of the chimney is inspected with a small video camera. Each mortar joint and tile can be carefully checked this way.

Before hiring a chimney sweep, ask if he will do a camera inspection that you can watch. If the chimney sweep immediately suggests you need a new chimney liner without doing a camera inspection, be skeptical. Installing a new chimney liner, especially with some of the newer techniques, can cost thousands of dollars.

Once the chimney is professionally cleaned and no internal problems were found, exterior and cosmetic problems are easy to repair yourself. Professional chimney repair products are available in smaller quantities for do-it-yourself use. Using a chisel and hammer, tap on the suspected bad mortar spots.

It will come loose easily if it is bad.

Fill the pits with special plastic-based mortar repair compound which matches the color of most mortar. Next spray or brush the entire chimney exterior with liquid water repellant.

James Dulley's column appears the first Saturday of each month. Send inquiries to James Dulley, The Journal Gazette, 6906 Royalgreen Drive, Cincinnati, OH 45244 or go to