Chimney Chase Covers

Dear AsktheChimneySweep,

My name is Rick and I’m from Illinois. After having my yearly chimney sweeping and inspection, the serviceman said that the chase cover had “rusted out” and needs to be replaced. I didn’t get a chance to ask him what this meant, he just left the invoice in the door with the recommended repair listed. I don’t even know what chimney chase covers are, is this is crucial fix? Money is short right now.



You wouldn’t know it but in the profession we see a lot of rusted out chase covers. My guys write estimates for replacing a chimney

Chimney Chase Cover Water Problem

This chimney chase cover allows water to pool instead of run off the sides.

chase cover a few times a week. What the serviceman wrote on your invoice means that the chase cover, also known as the chase top, which actually covers the entire top of your chimney to keep out the elements and critters. It fits over the top of the chimney like a lid almost, and the chimney flue pipe extends up through the middle. What has likely happened in your situation is that the chimney chase cover, which is more often than not made of galvanized steel which is prone to rust, was allowing water to pool and as a result became rusted. This isn’t necessarily a pressing repair, but should be taken care of in a timely manner because the rust damage will continue to worsen until holes form and water penetrates the chimney’s flue.

Water damages almost all kinds of chimney covers including chimney caps and the chimney crowns. When it comes to caps or chase covers, I always recommend stainless steel. The extra cost of installing a stainless steel cap or chase cover over galvanized steel is completely worth the extended lifetime of the cap and additional reliability that you also receive. Rick, when you do decide to replace your chimney’s chase cover, elect for a stainless steel version. Although rust stain removal is not usually extremely difficult, the metal has already been weakened so replacement is definitely the best option.

Other times, rust problems are worsened by a poorly designed chimney chase. The chimney chase should be designed such that it sheds water from the chimney and does not allow it to pool. As a rule, if water is allowed to pool anywhere, whether it be on top of a chimney crown or on top of brick or anywhere else, a water problem will ensue. The chase should actually be constructed so that there is a little bit of a slope from the middle, where the chimney’s flue will stick out, down to the sides. This will allow water to run off of the top of the chimney and prevent premature rust problems.

Chimney chase covers come in different designs based on how many flue systems are being vented through your chimney. There are chase covers available with two or three holes for multiple flues and chases where the hole is off center for specially designed chimneys. There are many custom chase cover manufacturers who will design your chase cover to your exact dimensions. You want to make sure that you are taking accurate flue diameter measurements during this process as well.

Rick, as I said before, I would definitely not let this problem go for too long because rust stains are more than just unsightly, once water is able to enter the chimney you experience more problems will surely begin to occur. Make sure you are choosing a quality material and that the chase cover is sloped downward to prevent water from pooling.


6 comments on “Chimney Chase Covers

  1. I was told I need my chase repaired. He will put down new stainless steel and seal with a rubberized sealant. He will also replace a missing 6″ cap. He is charging $1200 for the job which he says is a huge savings over replacing the chase completely—$2400
    I told I’d let him know…Is this a fair price for this repair?
    I have a Heatilator fireplace and I would say it is a standard size unit.

  2. chimneyadmin on said:

    When questioning a price it is a good idea to get 3 or 4 estimates and evaluations, from reputable contractors. I found that the majority will have a common persuasion and help narrow down your selection. Always check for references.

  3. I’d check out Chimney Liner Depot. Buy your own stainless steel custom made cover and install it yourself. You can call them, they’ll talk you through getting the correct measurements, and fabricate your cover for you. You won’t pay ANYWHERE near $1200 for it.

  4. chimneyadmin on said:

    But someone has to climb up there, take the measurement and climb up there again to install it. With chase covers you have to do this twice! (without Workers compensation). Most customer can’t clean their own gutters or put up Christmas lights without fear of falling off of the ladder.
    I always tell the guys don’t take it for granted, what you are able to do today while your young and comfortable on the roof top

  5. Sapo the chimney guy on said:

    $1200.00 for a stainless steel chase cover is not outside of the realm of possibility, it really depends on how long and wide, how many holes for flues to come through it, size of the drip edge, if you need storm collars or not and caps.

    You may think you’re very good at taking measurements and you very well may be, however I have had at least a dozen customers call me in after they “Measured their own chase cover” after getting estimates they thought were too high, Purchased the chase cover and tried to install it only to say they got up there no problem to measure but doing it with the chase cover in hand was impossible and changed their minds,so they called us to install it only to find out their holes were 2″ off center or worse in one case , not even close ! and the company they buy the chase cover for is not going to take it back once it is made it is sold case closed so then they’re stuck with purchasing the chase cover all over again and they’re stuck with a 600 dollar piece of scap stainless worth approx 20 bucks, trust me when I tell you it is not as simple as it sounds to take the correct measurementsif you make the hole the same size as the flue it will not fit always give yourself at least 1/2 inch play, install a collar and a storm collar and the 1/2 difference you’ll never even notice. The very most I have ever done a chase cover for was 3000 but that was an absolute monster with 3 rows of 7 10 ” holes! In a bulding across the street from Central park in Manhattan thinking back about that , I even went a little low just to get the job because I wanted the rest of the chimneys and there were many but that is a different story entirely :) and when in doubt just let a pro do it, it will cost a little more but if he messes it up he will be responsible for ordering another chase cover but if he’s worth his weight in dog dung, it will be spot on . . Best of luck to you all. Oh and a word of advice, if you hear a grinder going when that chase cover is being installed make sure they are not cutting the hole larger because they screwed up with the measurments , I have seen where “Custom chase covers were mis measured and the guy didn’t want to buy another chase cover so they just attempted to open the hole larger and that is NOOOOOOOOO GOOOOOOOOOD, then they seal around the guys brand new chase cover with TAR !!!1 OMG are you frigging kidding me ?

  6. Matthew on said:


    You ask if it is a crucial fix. I would consider it a crucial fix if you have water leaking through and damaging the inside of the chase and flue. This could lead to bigger problems down the road.
    I hear you when you say money is tight. I installed this myself and saved a lot of money. I’d recommend Rockford Chimney Supply, I did the price checking and they were most reasonable. Hope this helps.

    - Matthew

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