Your chimney might seem like a simple structure, but there are lots of parts that go into making sure it works properly. While most homeowners are familiar with the interior parts of the chimney, they have trouble identifying the outside. The chimney crown is one of the most important parts of the chimney and most people don’t realize that it’s even there. So what is a chimney crown and why are chimney crowns so important?
A chimney’s crown closes off the top of the flue to keep water, animals, and debris from getting into the flue. The crown is typically made out of cement and it’s the last line of defense against water damage. Damaged chimney crowns can quickly destroy the structural integrity of your chimney.
There are a few different styles of chimney crowns, but they all serve the same purpose. They keep things out of the flue and masonry. Repairing a damaged chimney is extremely expensive so don’t neglect crown repairs. In the rest of this post I’ll explain more about the crown, discuss inspections, and talk about sealants and repairs.
What Is A Chimney Crown and Why Are They Important?
It’s unfortunate that the chimney crown is one of the most overlooked parts of the chimney. For such a simple design it’s extremely important. What is the chimney crown and why is it so important?
The chimney crown covers up the top opening on your chimney. It keeps water, animals, and debris from getting into your chimney. Crowns serve a similar purpose to the flue cap, but there’s a major difference. The flue cap, which is typically made out of metal, only covers the top opening on the flue, a chimneys crown protects the entire flue.
Chimney crowns are usually made out of a slab of concrete, metal, or some kind of stone. It’s the last line of defense against water and debris getting into your chimney. Your chimney won’t last long without a well sealed crown and properly functioning flue cap.
Water will leak down in between masonry leading to major structural problems. As the weather changes, the water will expand and contract between the masonry in your flue destroying the structural integrity of the chimney. Plan on spending $3000-$5000 to repair a damaged chimney. It might be cheaper if there’s only minor damage, but it will still be in the $1000 range.
Types Of Chimney Crowns
- Cast-In-Place Crowns: Cast in place crowns are made out of concrete and suitable for large chimneys. They use steel or wood forms to construct the crown on-site.
- Precast Crowns: Precast crowns are used on small chimneys that are 16″x16″ or smaller. They’re also called precast chimney caps so don’t confuse them with the metal flue cap that goes on the top of your flue. You can usually find precast crowns at any business that sells precast concrete for sign bases, car stops, culvert ends, etc.
- Floating Crown: Floating cast crowns are built with an overhang that’s approximately 2″ above the chimney. Floating cast chimney crowns are harder to install so they’re more expensive, but they last twice as long. If you’re already paying for the repair man to come out it’s worth the minor price difference.
- Metal Crown: Metal crowns are commonly found on newer modular and manufactured homes. They’re cheap and easy to replace.
- Mortar Crowns (these are bad): There’s a decent chance you have a mortar crown if the mason that built your chimney also built the crown. Mortar crowns are fast and cheap to build, but they won’t last long when exposed to the elements.
Why Are Chimney Crowns So Important?
The most important and main purpose of a chimney crown is to protect the chimney structure from damage. With a damaged chimney crown weather exposure will cause your chimney to deteriorate fast. Properly functioning chimney crowns are able to do this by extending a few inches beyond the walls of the chimney.
A lip on the outside of the crown is called a kerf and should extend at least 2 inches past the main chimney structure. This overhang creates a makeshift rain gutter directing water, snow, and other sources of moisture out and away from the main chimney stack. Everything gets pushed out onto the roof where it can drain without damaging the bricks in your chimney structure.
Don’t Confuse Chimney Crowns With Flue Caps
Chimney crowns are commonly confused with the flue cap, which serves a similar yet very different function. They both keep out water, animals, and debris, but they protect different parts of the chimney.
A Chimney’s flue cap will almost always be made out of metal and goes over top of a mesh cage leading into your flue. A poorly functioning flue cap can cause major problems (fires, carbon monoxide, smoke, etc.) but a loose cap is fairly easy to diagnose. Either water will be running down the chimney flue or loose debris will be clogging the flue.
The crown serves a similar job, but it protects the masonry structure surrounding the flue. It falls a few feet below the top of the flue so there’s room for snow and debris buildup between the crown and cap. Damage caused by a leaking crown will be catastrophic to your chimney.
The structural integrity will be destroyed and you’re looking at 3000-5000 dollars for repairs. You might get lucky if you catch it early, but it will still cost up to $1000 to fix cracked bricks, replace mortar or repair a damaged crown.
How To Keep Your Chimney Crown In Good Condition
Most experts recommend hiring a certified chimney inspector to perform an annual inspection. Make sure you use a qualified inspector from a professional chimney service company. Some companies don’t have certified employees so pay attention to their reviews.
If you can’t afford to hire an inspector a quick trip up to the roof will be better than nothing. Look for cracks in the crown, signs of water damage, mortar failures, etc. You won’t be able to spot everything without specialized tools, but catching a cracked crown early will save you a lot of money.
When the crown’s cracked but still in decent shape you will be able to repair it yourself with crown sealant. Brushing on the sealant is just like spreading peanut butter on a sandwich. It doesn’t require an expert to do the job. However, if the crown is severely damaged it will need to be replaced. Minor cracks are fine, but a crumbling crown needs to be repaired immediately.
How Will I Know If My Chimney Crown Is Damaged?
Chimney crown damage can be difficult to spot since you can’t see it from the ground. That’s why crown damaged is rarely diagnosed until it’s too late for budget friendly repairs. The only way to avoid this is to get up on your roof to inspect the crown or hire a chimney inspector to take a look.
Certified chimney inspectors and even uncertified chimney sweeps will be able to immediately spot water damage. A chimney inspection will cost about $400 depending on where you live. So you might want to bring out a ladder and inspect the chimney yourself.
It really isn’t that hard to tell if your chimney crown is damaged. Inspect the crown looking for cracks, look at the exposed masonry, check the damper and firebox for rust, and keep an eye out for chips of broken flue tiles. You may even have water damage on your ceiling or walls inside the house if it’s really bad.
Water entering the chimney is the main cause of deterioration so you need to deal with a damaged crown immediately. Paying somebody to repair the crown won’t be cheap so you may want to do minor repairs yourself.
What Should I Do If My Chimney Crown Is Damaged?
Once you’ve diagnosed that your chimney crown is damaged you will need to make a judgement call. You need to make a decision based on how bad the damage looks. Small hairline cracks can be repaired easily with a waterproof sealant, larger cracks will need to be repaired with a high bond patching material, and severely broken cement will need to be torn out and rebuilt.
Repairing a chimney crown is one of those jobs that you may or may not want to do yourself. You can save close to $500-$1000 by doing a DIY repair, but you need to be comfortable on the roof. Almost anybody can repair hairline cracks, larger cracks, and mortar, but severely damaged crowns will be much harder. Most people can still do the job, but it won’t be an easy job.
Making a concrete form to build a crown isn’t that bad, but you will probably need to hire the job out if there’s damage to the structural masonry and flue tiles. Mortar damage can be patched, but crumbling bricks need to be torn out and replaced. It will take a long time, require expensive tools, and you need to know what you’re doing to prevent future damage. That’s a job that’s above most DIYers skill level.
I won’t get into explaining how to repair a cement chimney crown, but most jobs aren’t overly complicated. Head over to youtube and search repair chimney crown. There are 100s of videos showing you how to inspect and repair damaged crowns. It will cost a minimum of $500 (probably more) to get a repairman to climb on your roof so why waste the money for a 1-2 hr repair.
Seriously Consider Applying Chimney Crown Sealant
I highly recommend applying crown sealant to your chimney. Crown sealant keeps moisture out of the concrete which will protect your chimney for a long time. Brush on sealants are sometimes recommended for repairs, but they’re a temporary fix. Sealants are for extending the life of your chimney and shouldn’t be used for a permanent repair.
ChimneyRx brushable crown repair can be used on the crown and their Masonry Water Repellent can be used on structural brick. It isn’t the best crown sealer on the market, but it’s reasonably priced. Professionals typically use ChimneySaver CrownCoat because it lasts longer. The only problem is that it’s expensive since it comes in a larger 2 gallon bucket that’s way more than you need for a single job.
What If My Chimney Crown Is Made Out Of Mortar?
If the mason who built your chimney also constructed the chimney crown, it will probably be made out of mortar (not cement). Mortaring over a chimney is way faster than building a custom cement form, but it quickly deteriorates causing problems. While it’s the perfect material for binding bricks together it won’t stand up on its own exposed to the elements.
You can do a temporary patch job over the mortar, but you may want to chip out the mortar and replace the crown with cement. Building a small cement form and making your own crown isn’t that difficult. The only problem is you’re up on a roof which makes everything harder (and more dangerous).
What About Repairing Metal Chimney Crowns?
There’s really no middle ground when it comes to metal chimney crowns. If the metal crown is broken or badly rusting it needs to be replaced. Metal chimney crowns are cheap and almost anybody can do the repair if it’s a common size. Unusually sized metal crowns will need to be custom built. You probably don’t have a metal brake so that’s a job that will need to be hired out.
Replacing a metal crown is simple. Pry off the old damaged metal crown, run a bead of silicone around the edges, drill 3 holes in the new metal crown, fit it up over the chimney, and screw it down. The entire replacement process shouldn’t take longer than an hour even if it’s your first time.