Chimney Flue Caps 101

Regardless of whether you use your chimney or not, every chimney needs a cap. A chimney cap does several things. It keeps animals like racoons, bats, and squirrels from entering the chimney. It also prevents rain and other moisture from dripping down into the chimney flue or seeping into the insulation between a metal flue liner and the masonry surface. A chimney cap can prevent heat loss in the winter and loss of your air conditioning in the summer months and will protect your chimney’s crown from the elements, including ice, extending its life and decreasing the risk and likelihood of cracks.

A couple of things you should be aware of when installing a chimney cap:

  • Improper design or installation may restrict the draft of your chimney. This will increase the likelihood of smoking problems down the road. Make sure that the chimney cap you are installing is compatible with your chimney type and that it is installed according to the manufacturer’s directions.
  • Often times, the screen on your cap can become clogged with chimney byproducts, further decreasing the draft of the chimney. After installing a chimney cap, check it at least once a year to make sure the screen is not clogged.
  • In high winds, caps can potentially blow off, so make sure that the cap is fastened securely to the chimney.

Prevent Water Leaks With a Chimney Cap

If water is leaking inside your flue, it can actually increase your allergies. A damp, warm environment are the perfect conditions for mold and mildew growth. Also, rain will rust away your metal flue or the grate that your gas logs rest on. If you’ve ever had a leaking chimney, you may have noticed an odor coming out of your chimney. During the warm summer months, creosote inside the chimney can evaporate with the water leaking into the chimney, creating a foul odor. By capping your chimney, you can prevent water from entering your chimney, thereby reducing or eliminating any odor.

Stainless Steel Caps

There are many different types of Stainless Steel chimney caps available. Standard caps usually come with screens to keep animals out. Stainless steel is the most common cap material, as it doesn’t rust and discolor the brick or stucco on your home. It also hold up to the elements better. Stay away from painted metal chimney caps, as runoff can stain the chimney.

Galvanized Chimney Caps

Galvanized chimney caps are frequently used because they’re inexpensive, but the downside to these is that they have to be constantly repainted. If you do choose this type of cap though, it’s best not to use it with gas logs. The exhaust from the logs, which is very caustic, will eat right through the cap in a few years.

Copper Chimney Caps

If you use gas logs, you may consider using a copper chimney cap. This type of cap can withstand the corrosive exhaust from the gas logs. Copper chimney caps are the most expensive type and while they look very nice when first installed, after a few storms they begin to look like an old penny.

Draft Increasing Caps

Another type of chimney cap is designed for draft increase. If you have draft problems in your chimney, you may want to consider this type of cap. They are designed to increase the draw in your chimney, preventing smoke from entering your home. Stay away from mechanical caps which rely on windvanes or turbines. The creosote and smoke coming out of your fireplace will clog up the mechanics and quickly gum up the workings of these caps.

Caps With Internal Damper Systems

Some caps come equipped with internal damper systems. While more pricey, these types of caps can be great at preventing energy loss in your home. Lock-top and Seal-tight are two great manufacturers of this type of cap. These caps are retrofitted to the chimney and controlled by an inside mechanism. When closed, you can rest assured that none of your energy is floating up and out of your chimney.

Precautions

If you are installing a cap on your own, be sure to take these precautions under consideration. Wearing gloves is essential, seeing that sheet metal may have sharp edges. Be sure not to use silicone sealants on metal flues. The metal will get hot enough to ruin the sealant. If the cap you purchase comes with screws or adhesives, use them! This will protect you from possible fires and will better ensure that your cap will stay attached despite the elements.

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25 comments on “Chimney Flue Caps 101

  1. Martina Haback on said:

    My husband and I didn’t think we needed a cap because we burn our fireplace almost year round. We figure we’d smoke out any critters that may decide to nest. We had to pay a service fee for a company to come out and remove nesting materials from the chimney that could have caused a chimney fire. We bought a cap and paid to have it installed same day so we won’t have to pay for critter removal anymore.

  2. Have a ROHN wood stove Pipe is straight 6 inch flue, I burn real hot fires I use seasoned oak, everything works great , been burning wood for years. my problem is on the outside of the stainless chimney ther is tar running down on the out side of the pipe, have to get up there and wipe it down so it doesn’t get all over the shingles,at least 3 times a year. Burnt about a cord of wood just brushed it down got about 1 and a half cups of crap , inside the chimney looks great, can not think of any reason except the Cap. Help Me Jack

  3. Teddy Hedrick on said:

    Hey Chimney Expert~

    I really need your help…!!! We have a cap on our chimney that is operated from the fireplace by a chain that’s attached to the top of the cap. I wasn’t able to have a fire going when this snowfall of the century dumped two feet of snow on us. Now I can’t get the cap to open in order for us to make a fire. It’s a spring loaded dealy. I have had a space heater going up the chimney for a couple of days, if anything’s melted, you can’t tell. I also thought about having the neighor kids throw footballs at the snow piled up on that stainless steel cover. How in the world am I going to get that snow off there sooner than later? Any bright ideas? Should I try starting a small fire and yanking on the wire?

    Thanks for your quick response, the second storm is here and I hate wasting a prefectly good snowy day/night w/out a crackling fire!

    Teddy

  4. For your very unique situation I don’t have any bright ideas. Your football idea sounds interesting. Sorry for your snowed in situation.

  5. We have only a wire mesh cover on our chimney, but also had the big Washington DC area storm. Have lived in this house for over 30 years and just got to wondering WHY we have never had any snow or rain come down the chimney ??? We don’t use the fireplace so the damper is closed, but it is certainly not tight enough to prevent water from heavy rains and snow melt from coming through. ???

  6. chimneyadmin on said:

    Linda,

    Snow and rain very rarely falls straight down the chimney, which may be the reason why not having a cap has not affected you personally. Also, air flow patterns as the wind blows across the roof of the house, through surrounding trees, and over nearby hills can cause air to blow precipitation. Unless you begin experiencing weather issues with the chimney, the wire mesh should be sufficient at keeping out debris and critters. However, be sure to have the whole chimney inspected regularly as creosote buildup can occur in the openings of the mesh causing drafting problems and gasses to build up in the flue system.

  7. chimneyadmin on said:

    Jack,

    Be sure that the flue has time to warm up before you burn extremely hot fires. During the combustion process, vaporized creosote floats up and out of the chimney. If the pipe is cool up at the top, even if only in the beginning, the creosote vapors will cool and harden and a combination of downdraft and the chimney cap can cause it to condense on the area you have indicated. Try warming up the flue system by burning a little newspaper- this will efficiently warm up the flue and hopefully prevent your problem!

  8. Michelle on said:

    Dear Sweep
    We have a problem that we just can’t solve. We have yellow oily looking drips continually staining our chimney from top to bottom (on the exterior of our home). it’s driving us nuts. what can we do?

  9. Hi I hope you can help me, we have a chimney cap, during stormy weather we have severe smoke and the mess it leaves is awful. Please suggest which cap I should install and solve my problem. Thanks Nora…Ireland.

  10. Clay on said:

    For the smoking problem, it is forseeable that the barometric pressure outside of the home is higher than inside of the home during stormy weather. This will create a negative pressure in the home, causing the home to have to draw air from outside of the home by any means necessary to balance out the pressure disparity. Try cracking a window or to when you are burning a fire to replace the oxygen in the home that the fire is burning up. Please revisit our articles on smoking problems for more clarity. This should help significantly.

  11. Clay on said:

    Michelle, in thirty years I have never heard of anything like this. The only thing I could think of is liquid creosote, which may be an amber color. You can try applying a product called Anti-Creo-Soot (ACS) into the flue system and check to make sure that the screen on the top of the chimney is clear. The ACS will break down any creosote deposits and allow you to brush the creosote out of the chimney.

  12. Jane Hunt on said:

    Hi,
    I can’t help with your problem but could use your help. My son just purchased a house that has a Rohn wood stove but the previous owner did not leave a manual or an address so we can’t get in touch with him . We have burned wood for years but can’t figure out how to use this stove. Any help would be appreciated.

    Thanks
    Jane

  13. Jane,

    I’m sorry to say that I also have been searching for information regarding your Rohn stove, but to no avail as of yet.

    Actually the internet has been my only resource so far. There should be a metal plate attached somewhere on the stove with the model and serial number that may help you with a little more descriptive search.

    I’m sure the information that your looking for is available, but it seams to be hiding from us.

    You may want to check with the wood stove stores close to you. I find that with most of the stove dealers, they usually have a pretty good grip on the wood stoves that saturate their area.

  14. I’m just trying to find the name given to
    those bricks that are at the top of a
    brick chimney that jut out.

    The reason: I believe those are not just
    ornamental. I think they prevent down-draft
    due to wind blowing across the top.

    They act in a way similar to a wing on a
    plane. As the wind crosses the profile of
    the out-jutting bricks, the velocity of
    the wind increases, thus lowering the pressure
    that might press down on the outlet of the
    chimney. Hence the draw out of the house
    is undisturbed.

    After the Columbus Day storm, when our chimney
    collapsed, the brick-men rebuilt our chimney
    without this ‘lip’ or capstan (I don’t know
    what chimney-makers call this jutting ledge).

    They rationalized their thinking by
    attributing the chimney collapse to
    this lip around the top of the chimney.

    However, it seems more likely the flexure of
    the roof, which has 4 foot over-hang, as well
    as the fact there is an iron rod connected
    to the roof that passes horizontally
    through the chimney were the major
    contributing issues.

    We never had smoke or back-draft before
    the new chimney. Now, unless there is a
    large roaring fire, we get smoke blow-back.

    I’d appreciate any critique of my reasoning.

  15. cherry coffrin on said:

    I have a Rohn wood stove. The glass insert gets smoked over almost immediately after lighting fire. The only way I have found to clean it, is to put it in bathtub and scrape with razor blade. Is there anyway to keep glass from getting smoked over? Thanks, Cherry

  16. askthechimneysweep on said:

    I have heard that you can use ash from the fireplace and rub it on the glass to get it off. Oven cleaning products (less is more) may also help, but I would definitely recommend getting a hold of a Rohn dealer because it is my understanding that different manufacturers use different types of glass in the manufacturing of their glass doors which may have certain specifications. I searched extensively looking for a licensed Rohn dealer or even the Rohn wood stove manufacturers and had no luck on the internet. Try and contact whoever installed the stove for information on how to contact the manufacturer. I have a feeling that these stoves are older and may not be sold very extensively anymore. Sorry I can’t be of more help!

  17. askthechimneysweep on said:

    Since we cannot see this, I believe you are speaking in reference to a drip-edge crown which juts out approximately 3 inches from the brick chase. I’ve never heard of any conversation saying that this increases or decreases draft. It has always been my assumption that the purpose of a drip edge crown is to repel water from the brick chase. If you are actually talking of the bricks themselves, you are probably talking about whether the bricks “trumpet” out or “trumpet” in. There are many draft inducing caps available, and many other factors could be involved, including the pressures in the house, etc. It is my professional opinion that the exterior brick on the chimney have no effect on the interior flue system. You may want to have a different chimney company come out and evaluate the integrity of the new flue system with a video camera, and have them evaluate the factors in the home which may affect pressure inside the home. I hope this helps, burn safe and warm!

  18. cherry coffrin on said:

    Thanks, will try this ash cleaning. Don’t know who installed the stove. Will try to find a dealer for Rohn stoves. Never thought of using oven cleaner. I will try this also. Also, I had not used my stove for about 10 years, until now. When starting a fire, should the flue be open or closed? Then, after fire is burning, do you close flue? Thanks, Cherry

  19. askthechimneysweep on said:

    What you are referring to is the damper, not the flue, but the damper should be completely open when burning a fire and as it cools down after the fire goes out. After there are no more burning embers and the ash is most of the way cooled, the damper should be closed to keep your heated air in the home.

  20. we have a gas fireplace and I recently turned it on and the draft was clearly not going up. the damper was open for sure but I could see the flames actually coming toward the room instead of up so I turned it off and am afraid to turn it on again. It was really cold last night -17

    could the cold be the reason it was not going up? what should we do to get the draft going up?

    when we are not using the fireplace I have covered the vents on the sides and bottom that let in all kinds of cold air. I did remove these before starting the fire. Should I remove them for a longer period of time before lighting the gas fireplace?

    thanks

  21. askthechimneysweep on said:

    At this point I would have to agree that the cold air is just dropping down your chimney as you mentioned. I would think that the very cold day had a lot to do with this problem. Watching the flames backing up into the room is the confirming indicator of this down draft issue.
    Now here goes one of those things that I learned from a customer. Because they didn’t want that smoke smell rolling back into the living room, that would come from pre-heating the chimney with a light up burning news paper torch.

    If I recall they elected to used a heat gun or some type of air dryer to revere that cold air. They put the nose of the gun up into the damper area and where able to reverse the cold air flow. This allowed them to establish a wood burning fire draft up the chimney. Since theirs was a wood burning, my concern was that they possible would have to deal with the lingering smoke when it the fireplace began to died down over night.
    In your situation all you will have to do is shut it off and go to bed.
    Personally I would give it a try. I can’t think of any safety issues, other the the one your attempting to resolve, and that is carbon Monoxide. I will always recommend a CO detectors and be sure to follow the manufacture installation when ever a gas appliance is being used
    Remember almost all gas logs are listed as decorative appliance, an not long term heating devices so follow the instruction and burn safe and warm.
    Clay

  22. Elisa Milkes on said:

    I just came across this website in my quest to understand all the water that is leaking into the basement around two of our chimneys. We’ve had this problem ever since we bought our home 5 years ago. I’m wondering if anyone can help us figure this out. We have had contractors tell us that the chimney crown is fine (though they aren’t chimney experts), and that the problem is probably do to the suspected absence of a membrane between the chimney and the house (we have repeatedly found evidence of very poor construction practices throughout the house). However, I am wondering if all we need is a heavy duty rain cap. We do have a big piece of slate covering the opening, and there is screening over the flue to keep out animals, but that screening is flat. The two openings between the top of the chimney stone and the slate are quite large, and, in the case of the chimney that has the worst leaking by far, the openings line up with the west-to-east direction of the usual wind pattern. Could the problem be that the absence of a rain/wind cap is resulting in water traveling down the chimney stone and then bleeding out into the basement? Are there caps that are designed to shed rain completely?

  23. chimneyadmin on said:

    Elisa,
    The crown is fine, it is very rare for water to travel from the very top of the chimney all the way down to the basement. You would see other signs of water entry on the ceiling, walls, fireplace, any one of these places. I am going to give you a link to our video about chimney leaks. It shows different types of water entry problems. Check this out and some other articles on our site, I am sure it will help you.

    Click here for Chimney leak video!

  24. Looking for a 13×13 stainless steel chimney cap. I see products made by HyC and I also see products sold by HomeSaver. Are you familiar with these products, and can you comment on which of the two would be of higher quality?

    Thanks.

  25. chimneyadmin on said:

    I use both of these products daily and have for years.
    Check the size and buy it online. If your not “extremely comfortable” working off of ladders and roof tops, I would suggest contacting a local chimney sweep. You can find many of these companies on top of our http://www.askthechimneysweep.com web site, or under http://www.ncsg.org
    Please use caution and don’t worry about saving a few dollars when it comes to your ladder safety!

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