Chimney cap - a must have or over rated?

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David Tackett

Member
Oct 17, 2012
178
Waynesburg, Kentucky
This past March my mother in law passed away and the wife and I purchased her house. This house is 30 years old and has a chimney, no fire place. My Father in Law, who passed 2 years ago ALWAYS had a wood stove and used it constantly for primary heat source.
Well, now I am burning a wood stove in this house. I noticed there was no chimney cap and never has been for 30 years. I also noticed all the houses around me for miles have few to no chimney caps.
I understand their function, but it seems no one in my vicinity think they are worth the cost and trouble.
I was considering buying one, but it does not seem to be a must buy. What do you all think?
 

ColdNH

Minister of Fire
Oct 14, 2009
598
Southern, NH
I wish the previous owners of my house had put one on 26 years ago....
 

WhitePine

Feeling the Heat
Sep 18, 2010
497
I know of two things that can come down an uncapped chimney for sure, tree frogs and flying squirrels. It's great entertainment for house cats, if a tad messy in the end. Terrified drop-ins are great soot distributors.

And the cats can distribute visitor parts and fluids in the process. !!!

When we built this new house, a screened chimney cap was a requirement, not just because we are in the middle of the woods, but in order to keep out the wildlife.
 

John_M

Minister of Fire
Dec 10, 2008
614
Central NY
Many years ago I had a woodstove with a chimney cap WITHOUT a screen. During the entire non-burning season I would have a swallow or two in my stove about weekly. I had a heck of a time getting them out of the house. They would fly and poop. They would roost and poop. It was not fun except to friends who came over to help me get rid of the beautiful flying critters without harming them.

Installed a new cap WITH a 5/8" screen. That was the end of the swallow problem.

Have had screened chimney caps since then. :)

Best wishes and good luck.
 

Todd

Minister of Fire
Nov 19, 2005
9,402
NW Wisconsin
I think some people believe caps will reduce draft and creosote can build up on them. If you burn dry wood there shouldn't be a problem with that. My old heatform fireplace was all rusted out from 30 years worth of water coming down a capless flue. Caps are good in my book.
 

bag of hammers

Minister of Fire
Jan 7, 2010
1,447
Northern ON
Many years ago I had a woodstove with a chimney cap WITHOUT a screen. During the entire non-burning season I would have a swallow or two in my stove about weekly. I had a heck of a time getting them out of the house. They would fly and poop. They would roost and poop. It was not fun except to friends who came over to help me get rid of the beautiful flying critters without harming them.

Installed a new cap WITH a 5/8" screen. That was the end of the swallow problem.

Have had screened chimney caps since then. :)

Best wishes and good luck.

We have chimney cap but without screen on our stove. When burning weekends on a couple occasions we'd open the wood stove door when we arrived and find a bat or 2 inside. Sometimes still alive - then the fun begins especially if you have a vaulted ceiling. Once I didn't notice a bat in the cold stove (probably perched up on top of the baffle) until I lit the fire - poor little bugger didn't have a chance. Also found a squirrel in a sauna stove once. So far no birds though. A few critter episodes but all spread over quite a few years, so a screen hasn't become a top priority - however I wouldn't want any rain coming down the pipe into my stove, so cap is definitely a requirement for me.
 

baydraftmare

New Member
Oct 24, 2012
10
Roxboro, NC
We had a woodpecker come down our chimney during the rainy windy days of Hurricane Sandy this year. We were not at home at the time, and when we arrived it was dead, maybe from flying into a window. I do not know how long he/she was inside the house, but there was bird poop everywhere! It was sad and a complete mess, I'm still finding droppings that I have to clean up weeks later. When we purchased the house earlier this year there were bird droppings in the corners and window sills in some rooms. We assumed the previous owner had pet birds but after the woodpecker episode we think it was another bird down one of the chimneys, we do have 3 after all, I guess that increases our odds. A new cap and screen went on the one we are currently using when our sweep installed our new liner. The others have temporary tin covers for now.
 

Highbeam

Minister of Fire
Dec 28, 2006
19,150
Mt. Rainier Foothills, WA
I should clarify that I vote for and use a cap but no screen. In my experience burning dry and seasoned wood, the screen can become clogged enough to hurt draft with only a few months of burning. Good burning, good wood, good stove, clean glass, clean flue, but screen plugged with brown junk. I do not want to be going up onto the roof to clean the cap several times per year.
 

bag of hammers

Minister of Fire
Jan 7, 2010
1,447
Northern ON
It was sad and a complete mess

A small bird hit the front patio door last summer and landed on the ground upside down, wings still stretched out. My wife went back to keep checking on it (maybe it's not really dead...?). Well, before I could get the shovel to dig a hole, wouldn't you know it - the bird opened its eyes, then a few minutes later pulled in it's wings. Shortly after that, it flipped over, hopped around a bit, then flew away. Happy wife. All God's creatures.

Love the birds. The mice? Not so much. I never did tell her about the fried bat in the wood stove....
 

WES999

Minister of Fire
Jan 12, 2008
1,047
Mass north of Boston
I have caps on all 3 of my chimneys, 2 brick and 1 class A. I had squirrels building a nest in the basement stove chimney, I removed a trash bag full of branches they had brought in.!!!
The oil furnace would leak water out of the clean out during a heavy rain before I installed the cap.
So no I don't think caps are overrated.

I have a screen on the class A chimney, it has never come close to becoming clogged.
 

corey21

Minister of Fire
Oct 28, 2010
2,249
Soutwest VA
Chimney caps keep rain and wildlife out of your pipe that is a good thing to me.
 

bag of hammers

Minister of Fire
Jan 7, 2010
1,447
Northern ON
I may be losing it but I thought I once heard someone somewhere say that screens were recommended to keep floating embers from spewing out and landing on the rooftops(s). Does this sound silly? I suppose if you burned large amounts of cardboard etc you'd have some stuff floating around but that would be time to stop burning cardboard, as opposed to a screen...? Just askin'....
 

Sprinter

Minister of Fire
Jul 1, 2012
2,984
SW Washington
I may be losing it but I thought I once heard someone somewhere say that screens were recommended to keep floating embers from spewing out and landing on the rooftops(s). Does this sound silly? I suppose if you burned large amounts of cardboard etc you'd have some stuff floating around but that would be time to stop burning cardboard, as opposed to a screen...? Just askin'....
In my case, a screen was required. I believe it was part of the blanket "mobile home" requirements imposed regardless of build quality or age of the house. I'm told it is to prevent firebrands from escaping. I have no idea why mobile homes should be a special case anyway?

My installer told me that it would clog up quickly and that I should remove it. I'm just keeping an eye on it.

...Good burning, good wood, good stove, clean glass, clean flue, but screen plugged with brown junk.
Highbeam, do you know what that brown junk was? Creosote, I imagine, but was it worse than the chimney?
 

tlc1976

Minister of Fire
Oct 7, 2012
840
Northwest Lower Michigan
My cap was on the ground when I moved in. Had problems with starlings getting in. So I put it back on with good screws. Still get the occassional starling but not as many as I used to. But since I blocked them from the chimney, they have discovered my dryer vent and have torn it apart to get in the house multiple times. Have been working on a vent that lets the lint out but keeps the birds out.
 

weatherguy

Minister of Fire
Feb 20, 2009
5,805
Central Mass
I think some people believe caps will reduce draft and creosote can build up on them. If you burn dry wood there shouldn't be a problem with that. My old heatform fireplace was all rusted out from 30 years worth of water coming down a capless flue. Caps are good in my book.

Creosote does build up on mine and I have to go up there half way through the burning season to knock it off, I keep saying Im going to cut some of the wire so its big enough not to collect creosote but small enough not to let animals in, its on the to do list, or I may just buy a different cap that doesnt have those problems.
 

John_M

Minister of Fire
Dec 10, 2008
614
Central NY
Additional "For what it's worth" comment about screen in chimney cap: After burning about 12 cords of properly seasoned (> 1 year) mixed ash, maple, apple, and cherry I have yet to clean the screen. I drive to various locations in the yard and look at the screen with a clear sky as the background. The sky has always been clearly visible with no apparent clogging of the screen. There is a fine dusting of black but no apparent build-up of creosote.

I tend to keep the stove draft a little more open than it's most efficient burning position. This frequently hotter burn probably diminishes the risk of creosote build-up.

Good luck, best wishes and Happy Thanksgiving to all.
 

peakbagger

Minister of Fire
Jul 11, 2008
6,477
Northern NH
I did try a cap on my oil and wood flue a few years back. Prior to installing I checked the tiles and they were in great shape. Abotu a year later I was up on the roof and it was noticable that the oil flue was deteriorating rapidly and with 2 seasons, chunks were breaking off it. I ended up having the chimney replaced above the roof line and the cap never went back. I and the mason attribute it to my oil burner operation and the stack height. I run my boiler cold start and I expect the exhaust has enough SO2 mist in it that with stack there was just enough resistance to cause the acid gas to precipitate on the outside section of the chimney and eat the liner. I know that many cold start run a liner down the chimney to deal with this, but cinse the new chimney went in minus a cap i have seen no evidence or any deterioration. Of course in the last few years they have reduced the sulfur limits on heating oil so that probably has something to do with it.
 

Highbeam

Minister of Fire
Dec 28, 2006
19,150
Mt. Rainier Foothills, WA
Highbeam, do you know what that brown junk was? Creosote, I imagine, but was it worse than the chimney?

The light crunchy brown creosote. Flue was very clean, just the filter/screen/spark arrestor was packed with it, this was early in the season. This was a simpson brand cap and screen that uses the wire for a mesh. Entirely possible that our local wood species contribute. I burn everything which often includes cottonwood, willlow, alder, fir, elm, maple, or whatever else falls in the forest. I hate to see it rot.

Without the screen I have no problems with a clogged up screen. It comes out very easily and could be replaced in the summer if you had wildlife problems.
 
O

oldspark

Guest
Additional "For what it's worth" comment about screen in chimney cap: After burning about 12 cords of properly seasoned (> 1 year) mixed ash, maple, apple, and cherry I have yet to clean the screen. I drive to various locations in the yard and look at the screen with a clear sky as the background. The sky has always been clearly visible with no apparent clogging of the screen. There is a fine dusting of black but no apparent build-up of creosote.

I tend to keep the stove draft a little more open than it's most efficient burning position. This frequently hotter burn probably diminishes the risk of creosote build-up.

Good luck, best wishes and Happy Thanksgiving to all.
Yep thats the ticket, you guys are not burning your stove hot enough if the screen is plugging, one good reason to have a flue temp gauge (if you can on your setup), no cap is just asking for trouble IMHO.
 

heatwise

Feeling the Heat
Sep 13, 2009
436
ohio
We must have them mainly because of raccoons and I like keeping the rain out. The only time I've had issues with the screens getting clogged when years ago burning sensitive documents and pizza boxes . I stopped using paper and the screens stay clear. Most in our area are covered.
 
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