Height of Stove Pipe Above Roof Peak?


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Old 01-18-10, 01:40 PM
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Height of Stove Pipe Above Roof Peak?

I have heard that the top of a wood burning stove pipe needs to be a certain height above the peak of the roof to work properly. I used to have a flat roof on the house. The stove pipe wasnít far above the top of the roof, and wind blew smoke back into the house. I had the roof you see in the photos done in 1991. Plenty of height was added to the stove pipe, but whenever the wind blows, it will still blow smoke back into the house. Wood is no longer my primary source of heat, but I still like to burn a fire in the winter once in a while.

What can I do to solve this problem?

Can it be solved by adding another section of pipe?

If I added another section, (they screw together) would I need to redo the bracing to hold it to the roof?

The two photos show the stove pipe. The second photo has a red line drawn approximately where the peak of the roof intersects the stove pipe, which I determined using a bubble level. You can see the two braces holding the pipe to the roof.



 
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Old 01-18-10, 01:59 PM
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The standard rule is 2 feet above anything within 10 feet. That is a fire code and is for all of the US. But it does not mean that it will work. It looks like you need to add 18 inches at the least to be at the legal hieght. The taller a chimney the better it draws. As far as wind you should be taller than any point of your house as wind will come over the ridge and go back down to its origanal hieght.
 
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Old 01-19-10, 11:38 AM
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Thatís kind of what I was thinking, but wasnít sure, and didnít know how to find out. I think the Metalbestos comes in 24-inch sections, canít remember, and they do screw in. You can see the metal bracing in the photos. We get some very nasty storms in the winter, (weíve had two weeks straight of that kind of weather, and there is no end in sight), and if I stick another section of Metalbestos on, would I need additional bracing?
 
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Old 01-20-10, 10:34 AM
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Sorting a chimney and fire.

Chimneys always work best when they come out of the peak of a roof, they need to rise three feet above the peak.
A chimney needs to be warm to work properly, that means insulation where it is above the roof and also inside the home.

Note: When you are trying to light the fire, the heat from the fire has to lift a plug of cold air right up the full height of the chimney and push it out of the way, before the fire will get going.

Another point is that if you want a fire to burn slowly you must provide an air source.
Running a four inch pipe from the outside to as close to the fire as possible will do this.
Then you will have a good fire and no nasty drafts inside the home.

Final point, at times of high pressure, when there is no wind, these details are very important
 
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Old 01-20-10, 01:10 PM
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Just a couple more things I noticed looking at the picture again. 1st dont forgt to caulk the storm collar on the pipe. You dont want a water leak. 2nd looks like you will be ok on the braceing. You have to brace it when t passes through more than five feet and every five feet after that. 3rd Like perry had mentioned they do work best out of the ridge area but that will not work on most house designs and is a fireplace installers complaint all the time. We must do things we dont like or the next guy will. That does not mean it is illegal just that from experiance we know where the best area on houses is to run a flue up and out and architects and homeowners dont want to hear it they just say make it work. As far as the hieght above the roof at a ridge yes it is three feet it is always three feet min out the roof and two feet above anything alse within ten feet. Here is a link that might help you. http://www.duravent.com/docs/instruct/L150_Sept09.pdf Good luck and dont forget to put the bands on the pipe as well they require the bands just twisting them on is not enough.
 
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Old 01-22-10, 10:24 PM
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Metalbestos (Selkirk now I believe) comes in several lengths, including 12", 18", 24", and 36" maybe more, but that usually gets it done.
 
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Old 02-07-10, 12:42 PM
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Sorry for the delay in getting back to this thread. I wanted to take some dimensions, and put them on a photo to post with my next post. While putting the dimensions on the photo, some just didnít make any sense, and I had to wait for a day without gale force wind and rain to go back up on the roof, and re-measure. Been an ugly winter.

What Iím thinking of doing is adding one more 24-inch section of pipe, which will bring the top of the pipe 30-inches above the roof peak. Currently, the pipe is 6-inches above the roof peak. Hopefully, this will be enough.

This will bring the total height of the pipe (Not including the cap) to 85-inches. (7-feet). In the photo below, you can see where the braces currently attach, 41-inches above the collar. Would I need to move this brace higher, or would it be ok where it is?

I want to do everything correctly so that the pipe remains standing, and stable. You can see two skylights right under the pipe. My Lazyboy is directly under these skylights, and I would hate to have the stove pipe come down thru the skylights, whether Iím sitting there or not. If the pipe was to fall in the other direction, it would land on a car.



The stove was in the house when I bought the house in 1980. At the time, the roof was flat. The contractor that put the new roof on also put the extensions onto the existing stove pipe. He did a very nice job, just didnít get it high enough.
 
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Old 02-10-10, 12:25 PM
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Chimney gusting wind speed, anchor?

There are a number of factors in this.
What sort of exposure does the house have?
I can see trees in the background, are they all round?
What sort of protection does your home have from the wind?

The other side of the question is, how is the pipe fixed inside the attic/roof?
Is there anything to stop it swing about?
You should be able to find the average wind speed, but the important one is the gusting speed.
 
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Old 02-10-10, 01:05 PM
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I am in a valley that is surrounded with ridges on three sides, and open to the west, where the Pacific Ocean is about a mile away. During storms, prevailing winds come from the south (The photo faces East), but the winds swirl around in this valley, and south winds can bounce off the northern ridge, and come back in here in all kinds of directions. Gusts typically are 30 to 60 mph, but Iíd say weíve had much much higher. When the whole house shakes and rumbles, it gets kind of scary. Gusts at the beach can be up to 100 mph and faster. I loose shingles every winter, but have lucked out so far this winter. So one can understand why I want this pipe braced properly.

There are fewer trees on the sides and front of the house, but there are some trees. Just in back of me when I took this photo is a fir tree that is higher than the roof.

The stove pipe is on a north facing roof. With all our rain, I need to get up there with a pressure washer almost every year to get the moss off. Itís time to do that yet again as evidenced in the photo.

Inside the attic is the old collar that was on the old roof. This roof was put on top of the old roof, which is now the attic floor. I do not know what the parts are called, but it is very well attached to the new roof. You can not wiggle the pipe at all, either in the attic or on top of the roof, and it does not leak.
 
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Old 02-11-10, 12:27 PM
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Correct height of flue

You are in rather an exposed position and I think you should stick with what you have at the moment.
The top of your chimney should be no less than 17' 6Ē above the highest air inlet point of the fire.
At the same time it should be at least 2 feet higher than any part of the building that is within 8 feet.
However, because of the potential exposure risk of high winds, keep it as it is, unless it is below the 17'6Ē mark, when raising it will give you a better result.
If you do decide to raise, add another collar with braces.
 
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Old 02-12-10, 03:05 AM
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Strong winds, useful trees?

I'll just come back on this once more.
I live in much the same sort of place 433 feet up, with the wind roaring up the valley from the sea 12 miles away.
Since we grew some trees, Leyland Cyprus, Beech and Willow to the North, Beech and Oak to the East and Oak, Willow and Beech to the South the wind just passes over the top.
Our view is mainly across the valley to the West so we have one each Oak, Beech, Scot Pine, Cracked Willow and Silver Birch with a number of Oriental Hawthorn that are cut to ten feet to retain our views. Hawthorn will grow to 30 feet and works well were there isn't much space.
This has worked well for us, our weather station rarely goes above 6mph.
 
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Old 02-12-10, 01:12 PM
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Had to wait for a break in the weather to take measurements, as I would have been blown off the ladder trying to get onto a roof I would have certainly been blown off of.

It is 15.2-feet from the highest air inlet point of the stove to the top of the stove pipe on the roof.

Any wind at all, and I can not have a fire. I’m glad I no longer depend on wood for heat, but I still would like to use it on those cold winter nights. Would have been nice to light the stove a couple of weeks ago when we lost all power for almost 8 hours, but the winds were much too strong, and I mostly would have succeeded in filling the house with smoke, so we got pretty cold, and when the temp drops down into the lower 40's, the insulation in this house is poor enough that the electric furnace just can’t seem to take the chill off. A fire for those times would be nice too.

Adding another brace isn’t something I want to do. I really don’t feel like punching more holes into the roof, or is it maybe possible to add a new brace, attaching to the existing anchors in the roof along with the existing brace?

Do you think adding another 24-inch section of pipe and another brace would fix my problem of not being able to have a fire when it is windy outside?

(Planting more trees is not an option).
 
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Old 02-13-10, 03:46 AM
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Chimney problems, air supply, insulation, heat loss.

I guess that whoever installed your fire didn't quite work it out.
If you want a fire to behave itself, you really do have to get it right.
The chimney needs to be insulated and the right diameter and length to suit the size of fire.
It also needs a clean air supply- there is no point in letting the fire burn the warm air in the room, it really does need a supply directly from the outside, to as close to the fire as possible, then the fire uses cold air to burn and your room keeps warm and more important is cheaper to warm.
By the sound of it, not only is your chimney too short, it possibly is not insulated and it is struggling to find enough air to burn and it is burning too cold, due to the throat of the fire being too big.
You cannot run a slow fire at tick over without everything being right.
You can sort the height of the chimney by adding a couple of feet, an extra collar and by attaching the supports to the existing fittings. Then sort out the air supply, either run a four inch pipe under the floor or drop a four inch pipe down from the roof space. Then go round the home and seal every hole that you can find, especially round the windows and doors, and where the light fittings go through the ceiling, take a careful look at the floor. this will stop a lot of drafts and make the home a lot warmer.
When you have finished build a roaring fire then go round the room with a candle and watch the flame bend where there is a draft coming through.
When you are not using the fire, block up the flue pipe to stop the wind dragging your warm air up the pipe.
Then consider, fitting three to four inches of polystyrene inside all the outside walls, the ceilings and under the floor. Then to make the job perfect fir another two inches of polystyrene across the inside/room side of the walls and ceiling to stop the heat loss through the wood.
Most heat is lost by the passing wind sucking the warm air from the home.
The next level of heat loss is by conduction through the fabric of the home.
 
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Old 02-13-10, 06:52 PM
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Just a side note. I would install an electrical mast support, it appears yours is bending towards the street pole? Add ridge ventilation if not already installed on the other side...
Flash the addition's rake board/roof connection at the angle cut probably not painted underneath.

Be safe, Gary
 
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Old 02-14-10, 08:01 AM
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Originally Posted by GBR in WA View Post
Just a side note. I would install an electrical mast support, it appears yours is bending towards the street pole? Add ridge ventilation if not already installed on the other side...
Flash the addition's rake board/roof connection at the angle cut probably not painted underneath.

Be safe, Gary
============================================

There seems to be a lot of misunderstanding regarding roof vents.
Why do you propose a roof vent?
What exactly do you expect it to do?
Do you imagine there is a need to have a howling gale blowing through the roof.
When the modern Passive House standard asks for a totally air tight building to save on heating costs?
 
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Old 02-15-10, 10:51 AM
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Originally Posted by Perry525 View Post
I guess that whoever installed your fire didn't quite work it out.
Thanks for your help. Sounds like my best bet would be to add another 24-inches of height to the pipe, and add another brace. I just hope I can use the existing brace brackets for both braces, as I really donít want to punch more holes into the roof.

I met the guy who built this house years ago. He said it was his first ever, and he didnít know what he was doing. I donít know if he put the stove in, or whether it was done later by someone else. The stove is a Fisher. I believe it was called a ďBaby FisherĒ. It will cook you right out of the living room. Itís great on those cold nights, but not if the wind is blowing. The stove pipe has a damper about 26-inches above the center of the pipe where it comes out of the stove. It comes out of the rear of the stove, then makes a 90 degree bend up towards the ceiling. Iíve never liked that setup, and if wood was still my main source of heat, I probably would have replaced the stove a long time ago. The house is old and drafty, tho I have done a lot of work to seal it up. When I bought the house in 1980, the front door was an inside door with about a Ĺ to 3/4 gap under the door just to give you an idea of what the builder and previous owners thoughts on insulation was. Several rooms in this house were not insulated at all. About 5 or 6 years ago, I took some of the paneling in the living room off for a wiring project. To my amazement, there was zero insulation. That little wiring project let to an insulation project.

The stove pipe is plain thin walled stove pipe till it reaches the collar at the ceiling. From there on, it is insulated metalbestos pipe.

Iím not understanding what you are saying about running a four inch pipe from the outside to as close to the fire as possible.
 
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Old 02-16-10, 04:41 AM
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Chimney, wind, high pressure, problems.

That stove is an antique, a bit of a collectors item, it's 30 to 60 years old I would guess.
In those days pre 80's these stoves were not very efficient and created a lot of smoke, more modern stoves are 80 to 90% more efficient, and create a lot less smoke.

The way a stove works is, it pulls air through all the gaps and holes in the fabric of your home.
This causes it to struggle at times, especially when there is an area of high pressure and the stove is burning slowly.
The idea of having a hole in the fireplace under the stove is to provide an easy source of fresh air rising under the stove, or as close to it as you can get.
If you have just a hole, the fire will drag the the cold air from the outside under the floor making your floor and home cold.
Having a pipe that crosses the crawl space to the outside keeps the cold air in the pipe.

When a fire is pulling the air it needs to burn from the room, through gaps in the walls and floor, you burn air you have already paid to heat and you end up cooking on one side and freezing with the cold draft on the other, not good.

Your problem at times of strong winds, is part of this.

The wind blowing over and round your home, causes a pressure drop on the lee side.

This pressure drop pulls air from inside your home through all manner of gaps in the fabric.

As your 8 inch flue is the biggest hole, it pulls the smoke down the pipe into the room, then out through these holes to the outside.

That is why at times of strong winds, you need to kill the fire, close the damper and seal off the flue.

What you should do is seal all the holes and gaps in the walls, ceilings and floors to stop this suction effect, this will give you a warmer cheaper to run home.

Then, because you like to have a fire from time to time, you either open a window or door, to let the air that the fire requires in, (a waste of money) or you provide an air source close to the fire so that the fire burns cold air and the warm air in the room stays in the room.

By the way, my first house was much like yours, you could stand out the front, look under the front door straight through the house under the back door and see the sun shining on things in the back yard. Good old days?
 
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Old 02-20-10, 12:39 PM
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Yes, the stove is old. It was in the house when I bought it in 1980.

So, are you saying it would be a waste of time and money to add another extension to the pipe on the roof?

There is a window behind the stove. Iíve never tried opening it when it is windy, but open it when the stove starts to smoke. Thatís when I usually open the window and doors to let the smoke out, and let the fire go out.

Here is what the stove looks like from a cheap camera between the removal of old rug, and installation of new carpet several years ago. I still keep a plant on top of the stove when not burning something. It is a 6-inch stove pipe, and I have always hated the way it comes out of the back of the stove. No pipe elbow fits it properly.

 
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Old 02-21-10, 11:29 AM
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Short chimney, area of high and low pressure, wind effect

The fact that it's old, fires go on for ever, isn't the problem.

The problem is the winds suction effect on the home.
The wind is sucking all your expensive heat out of the home and is dragging in cold air from the other side and or down the chimney.
The only way to stop it, it to seal all the holes, cracks and gaps.
When you have done that, the fire will not work, as it needs an easy source of air to burn.

From a practical point, being able to source air from outside is good, but what you don't want is for the air source to be on the lee side of the building to add to your troubles. From this point of view a simple hole through the floor, with the air coming from all sides via the crawl space is good, but this is offset by the fact that pulling cold air under a floor that is not insulated, will lead to cold feet.

The extension to the chimney is really to make if burn correctly at times of high pressure, when it will struggle to burn. It won't make any difference at other times.
 
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Old 02-21-10, 09:27 PM
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The floor is insulated. The insulation in this house may not be up to current standards, but it is insulated. Iíve lived with not being able to have a fire in windy conditions for 30 years, guess Iíll keep on like I am, but it sure is frustrating. Thanks for your time.
 
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Old 01-09-15, 09:35 AM
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I don't understand what the 'lee' side of the house is

And.... We are building a new log home and the wood stove will be located within a few feet of the ridge beam. The ceiling height of this room is 23'. I saw where it was not recommended to have a stove pipe over 17' +-. What will we do?
And.... I saw where it is recommended to have a 'fresh air' vent near the fire. I know the 'why' of this but I want to ask how you get fresh air into the woodstove? We have an old woodstove that was given to us that has firebrick. I know I need to test it before I install it to see if it has leaks, etc. But I can almost bet it has no fresh air intake. We are building this home over an encapsulated crawlspace so we would have to bring fresh air in from a hole in one of our logs I imagine. I don't like the idea of making a hole in a log so I want to be sure that is my only option and where, on the wood stove, would it have to enter?
 
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Old 01-10-15, 10:30 AM
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Making sure your fire burns as you want it too.

The leeward side of a sailing ship or building is the downwind side.

To ensure a fire burns well, without it smoking, when you are in the middle of an area of high pressure (ie; there is no wind)
You need a chimney that is more than 16 feet high, from the highest point that air can enter the stove to the open top of the chimney.
The best chimney design is one where there are two bends each at 30 degrees between the fire and the top of the chimney.
Keep as much of the chimney as possible is inside the building, to keep it warm, as a cold chimney will cool the burnt gases and will cause them to drop down the chimney filling your home with smoke.
The top of the chimney must be 3 feet higher than the highest part of the roof (And any nearby things.) and which again must be insulated to keep it warm.
It also needs a cap to keep out the cold rain and snow.

The stove will not burn at a slow rate, without going out, if it struggles to find air to burn - especially at times of high air pressure, therefore you must have an air supply.
Most people never think about, where will my stove get its air from? They simply do not think. But your fire will only burn well if you provide enough air. Most fires have to pull air through cracks in the home. When you do this, you get drafts across the floor, you sit by the fire, your front is warm, your back is cold.
Your fire burns air you have already paid to heat! How sensible it that?

But, if you provide a hole under the fire itself, then the fire will burn cold air......and your room will be warm and draft free. Your home will be cheaper to heat, your warm air will stay in the room.

Your old stove, was built with enough holes in it, for it to work as designed. Some modern stoves have purpose made holes, but you don't need to consider this.
Bring the air into the fire through a sewage pipe through the crawl space a six inch diameter pipe will be just fine. Keep in mind the direction of the prevailing wind.....you don't want the wind blowing along your pipe.

Please be advised that your crawl space needs to be air tight. If you are building with blocks, then do a cement render over the outside of the crawl space walls, or the inside.
This will block all the thousands of tiny holes in the walls that both air and water vapor can flow through.
Make sure you insulate over the floor, sheets of polystyrene are good for this.

Keep in mind that heat always moves to cold and that there will be masses of space below the floor, plus the joists themselves, that your heat will disappear into. Relying on crawl space walls is pointless, as most of your heat will end up in the ground.
 
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Old 01-10-15, 11:48 AM
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Welcome to the forums.

We are building this home over an encapsulated crawlspace
Can you elaborate on that ?

I would think you could still bring an insulated fresh air duct in thru the crawlspace.

Thanks for the additional information Perry.
 

Last edited by PJmax; 01-10-15 at 05:41 PM. Reason: added info
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Old 01-10-15, 03:36 PM
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Hi pattiecake51,
If you come back, I'll watch, but I disagree with virtually the entire post from Perry. I won't go into details until I know your are interested. BTW, I own and use a wood stove on a regular basis and having one centrally positioned in a new log home would be absolutely delightful.

Best, from Maine where we burn wood.

Bud
 
 

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