Chimney maintenance is important both inside and out

We use our woodburning fireplace for heat. It has not been cleaned out for the year, and we noticed bad spots on the outdoor chimney brick. What maintenance steps can we do ourselves?

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 these are not as serious as issues inside the chimney. The most common problem inside chimneys 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.

Many homes have small chimney fires from creosote buildup, and the homeowners are not aware of these fires. If you have ever noticed a sudden increase in the fireplace draft, this is a sign of a chimney fire. The heat from the creosote burning creates the strong draft.

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 backdrafting. 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 cause the wall framing to catch fire. Wall framing may burn 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 will be 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 or she will do a camera inspection that you can watch. If the chimney sweep immediately suggests that 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 has been professionally cleaned — and if no internal problems were found — exterior and cosmetic problems are easy to repair yourself.

Professional chimney-repair products are available in smaller quantities for doit-yourself use. When working on a roof or high on a ladder, always be sure to wear a harness that is secured to the structure, and have a helper support the ladder.

You might think that brick and mortar are very hard, but they are permeable to water. Over years of exposure, outdoor moisture can penetrate and deteriorate the mortar, as you have noticed on some posts. This is most common in regions that experience many freeze/thaw cycles over winter.

Using a chisel and hammer, tap on the spots where you suspect the mortar is bad; mortar will come loose easily if it is bad. Fill the pits with a special plastic-based mortar-repair compound that matches the color of most of the mortar. Next, spray or brush the entire chimney exterior with liquid water repellent.

If there is deteriorated mortar, you will likely also find that the chimney crown (the top of the chimney through which the flue passes) has problems. As with the mortar, chip away the bad crown spots, and fill them with compound. Finish by coating the entire crown with a thin layer of repair compound. Special compounds that cure below freezing temperatures are available for winter application.

While you’re up there, check the condition of the metal flashing between the chimney and the roof. Unless it is severely rusted (which will require replacement), coat the joints with flashing compound, and paint the flashing.

I added a room to my house. It is efficient, with thick-batt attic insulation, and I’ve got some extra insulation left over. Is it important to have the same insulation level in the attic over the existing rooms too?

It is not critical to have the same insulation across the entire attic floor. More insulation is always better, though. Even if you cannot cover the entire attic floor over the existing rooms, cover as much of it as you can with the extra.

Unfaced batt insulation is best to use for the second layer. If the leftover batt insulation has a vapor barrier, cut slits in it with a knife; otherwise, it can trap moisture between the old and new insulation layers. Send inquiries to James Dulley, Arkansas Democrat-Gazette, 6906 Royalgreen Drive, Cincinnati, OH 45244 or visit www. dulley.com.