Chimneys are one of those parts of the house that are so prevalent they’re invisible—you see them all the time, and probably rarely think about them. Even if you have one in your own home, if you don’t have a fireplace you might assume that your chimney is a useless artifact poking up out of your house—but that old chimney might still be serving a purpose. Even without a fireplace, your chimney is very likely serving as ventilation for the house, letting dangerous gases from your furnace, water heater, or other infrastructure escape the house instead of killing you.
Whether that old chimney on your roof is in use or not, it’s a huge mistake to ignore it. Like everything else in your house, your chimney needs to be properly maintained, even if it’s no longer in use. There’s one obvious reason why: The cost to remove or replace a chimney is steep: About $4,100 on average, and sometimes more than $6,000. Rebuilding instead of removing will still run you anywhere from $1,000 to $10,000 depending on its size and condition. Ignoring your chimney is an easy way to damage your roof and other areas of your house—sometimes disastrously.
Inspect it
Unless you’re a chimney expert yourself, you should have your chimney inspected on a regular basis—annually, if you can. You’ll want to hire someone certified by the Chimney Safety Institute of America (CSIA), who will check out the structural integrity of your chimney, check to see if it’s clogged with debris or flammable residue like creosote, and ensure that it’s still performing its functions properly.
Sweep it
If the words “chimney sweep” conjures up visions of Dick Van Dyke in Mary Poppins, you might be surprised to learn it is very much still a thriving profession. “Sweeping” a chimney is basically cleaning it out—over time, every chimney gets clogged up with ash, debris, and other substances. Even if you don’t have a fireplace, your chimney can become clogged up over time, and probably needs a good cleanout.
If you schedule an annual inspection of your chimney, the company probably includes a sweeping service, or offers it at a small additional cost.
Cap it
Whether your chimney is in constant use or you were recently surprised to discover you have one, it should be capped. A chimney cap is a cover that is attached to the top of your chimney to prevent rain and snow from pouring down into it, damaging the interior. Some also have mesh screens incorporated to prevent animals and birds from building nests in there or migrating down into your walls. They’re not particularly expensive—this one from Master Flow is less than $60—but they can save you a ton of money and stress in the long run. If you’re somewhat handy and follow proper safety precautions when working on a roof, installing a chimney cap is a fairly straightforward DIY job.
Seal it
Your chimney pops up out of your roof, so it gets hit with all the weather and rain. Over time, water penetrating the brick and mortar will inflict some serious damage, so it’s a good idea to seal it against water intrusion using a penetrating water repellent product. This is an easy and cheap job that can help preserve your chimney structure so it doesn’t crumble and magically transform into an expensive repair.
Line it
A chimney liner is fitted inside your chimney, made of metal, clay, or a concrete-like mixture that’s poured into the chimney to set in place. It can serve two vital purposes: protecting the interior of your chimney from corrosion and damage, and making your chimney more efficient. If your chimney is too large (older chimneys sized for old-school furnaces or fireplaces can be way too big for a modern, more efficient furnace, for example), the gas outflow can cause condensation and moisture inside the chimney, which can damage masonry and other materials. A liner can “resize” the chimney so that doesn’t happen, while also protecting those materials.
Close it
If you are absolutely sure you don’t use that chimney for anything—furnace outgassing, ventilation, etc.—but you don’t want to go through the trouble and expense of removing it, you might consider closing it up entirely. This involves sealing it up at the top and bottom so that there’s no chance of water intrusion or other problems. Keep in mind you’ll still need to maintain the structure of your chimney with inspections, capping, and water sealing if you choose to do this.