Chimney with rusted chase cover

El Niño is coming, and Patrick is fretting about waterproofing the house. I told him I’d take care of the chimney.

The first thing, says Terri Pocock of Swede Chimney (858-573-1672), is to visit csia.org, the website of the Chimney Safety Institute of America. “There are no regulations on our trade,” she explains. “You can say you’re a chimney sweep, but it doesn’t mean you know squat about chimneys. CSIA provides certification. They give special training on building and fire codes, and you have to take a test every three years to stay certified. If you visit the website and put in your zip code, it will give you a list of all the certified chimney sweeps within a 60-mile radius.” The second thing is to call in the offseason, when prices are generally lower and wait times shorter. “Our initial inspections are $89, and if a sweep is needed to complete our inspection of the chimney lining, that goes up to $149 in the off-season and $189 in the busy season.”

Chimney with cracked crown

One of the chief exterior inspection points is the crown. “The crown is the cement mortar at the top of your chimney, if you have one of the old masonry chimneys and not the metal prefab kind they started building in the ’80s. Between the weather and the heat of your chimney, it’s very common for a crown to develop cracks. If the cracks are minor, we’ll resurface it with a paste that fills the cracks. It’s impervious to water, and has a ten-year warranty. Price will vary with size, but I’ll say the average cost is $275 to $350. I tell people that the small cracks don’t ever go away, they just get more expensive to fix. If you don’t resurface, you can end up needing to replace the crown.” (Swede also sells stainless — not galvanized — steel caps with a ten-year warranty for $160–$170.)

If a crown stops doing its job of keeping water out of the chimney’s masonry shell, says Marietta O’Mara of Weststar Chimney Sweeps (619-338-8116), “then water eventually seeps into the shell and attacks the rebar that holds the chimney together. As the rebar expands with the moisture, the top of the chimney will crack and deteriorate. Eventually, it will need to be replaced, and that’s ten times more expensive than getting the crown repaired.” Inspections at Weststar are $79, bumped to $139–$169 if sweep is needed. Crown resurfacing starts at $179; if more significant crown repair is required, it’s $269 and up.

O’Mara also stresses the importance of cap/spark arrestors. “There are lots of reasons to have a cap. For one thing, it keeps water from going into the flue and dripping down into the firebox. A lot of masonry chimneys have a metal damper in them, and they can rust completely and freeze. A cap also helps to keep animals out of your chimney. We get birds in there all the time; once, we had to call animal rescue to remove a raccoon and her babies.” And it keeps sparks off of your roof. “We have a stainless one with a lifetime guarantee for $189.”

Michael Morrison at Chimney Champ (619-888-8311) charges $85 for an initial inspection, bumped to $119–$149 if a sweep is required. New cap/spark arresters cost $90–$150, and crown repairs on masonry chimneys run $200–$500. He also noted that prefab chimneys have their own troubles.

“A prefab chimney is basically an empty box called a chase, with a metal pipe going up the middle of it. There’s a piece of metal at the top called a chase cover. That can rust out and leak. When it gets bad enough, you’ll hear it dripping onto the firebox when it rains, and you’ll know you need to replace the cover so the water doesn’t rust out the firebox. Then you’d have to replace the whole system. But it can also just trickle down the inside of the chase and cause wood damage to your home. How long a chase cover will last varies according to how often the fireplace is used and how well it was installed. Some contractors situate it so that water just pools on it. And some nail it in through the top. Chimney sweeps will nail it in from the side, and we’ll use supports to make sure that the water runs off, so that no water can go through. Installed correctly, they should last 20 years or more. We have to have them custom-made for particular chimneys, and cost is $250 to $600.”