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Default Flue extending beyond crown on a chimney

Why are so many chimneys built with the flue(so) that extend above the
crown?


For Looks?

To improve the chimney draw? I would think the small increase in height
would make little or no difference

To allow the chimney to meet code? I would think the chimney could just
have been built at the correct height in the first place.

Sheldon


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Default Flue extending beyond crown on a chimney

On Sep 13, 12:32*pm, "Sheldon" wrote:
Why are so many chimneys built with the flue(so) that extend above the
crown?

For Looks?

To improve the chimney draw? *I would think the small increase in height
would make little or no difference


Makes a world of difference

To allow the chimney to meet code

*I would think the chimney could just
have been built at the correct height in the first place.

Sheldon


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Default Flue extending beyond crown on a chimney

Sheldon wrote:
Why are so many chimneys built with the flue(so) that extend above the
crown?


For Looks?

To improve the chimney draw? I would think the small increase in height
would make little or no difference

To allow the chimney to meet code? I would think the chimney could just
have been built at the correct height in the first place.

Sheldon


AFAIK, the code requirement in most areas is that the flue must extend
at least 2" above the crown. YMMV

Picture wind gliding across a sloped crown with no flue extension. You
can almost imagine the wind sort of sealing the flue opening.

Now picture wind gliding across a sloped crown and hitting the wall of a
2" extension. The wind is forced upward instead of flowing across the
opening.
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Default Flue extending beyond crown on a chimney

On Sep 13, 1:07*pm, DerbyDad03 wrote:
Sheldon wrote:
Why are so many chimneys built with the flue(so) that extend above the
crown?


For Looks?


To improve the chimney draw? *I would think the small increase in height
would make little or no difference


To allow the chimney to meet code? *I would think the chimney could just
have been built at the correct height in the first place.


Sheldon


AFAIK, the code requirement in most areas is that the flue must extend
at least 2" above the crown. YMMV

Picture wind gliding across a sloped crown with no flue extension. You
can almost imagine the wind sort of sealing the flue opening.

Now picture wind gliding across a sloped crown and hitting the wall of a
2" extension. The wind is forced upward instead of flowing across the
opening.- Hide quoted text -

- Show quoted text -


extension helps screw chimney cap on......... try to do it with "
flush flue"
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Default Flue extending beyond crown on a chimney

Sheldon wrote:
I cannot find anything on the web that indicates that the flue has to extend
2" beyond the crown.

The chimney has to be 3' beyond the portion of the roof where it emerges.
The chimney also has to be 2' higher than anything that is within 10'.


"DerbyDad03" wrote in message
...
wrote:
On Sep 13, 1:07 pm, DerbyDad03 wrote:
Sheldon wrote:
Why are so many chimneys built with the flue(so) that extend above the
crown?
For Looks?
To improve the chimney draw? I would think the small increase in
height
would make little or no difference
To allow the chimney to meet code? I would think the chimney could
just
have been built at the correct height in the first place.
Sheldon
AFAIK, the code requirement in most areas is that the flue must extend
at least 2" above the crown. YMMV

Picture wind gliding across a sloped crown with no flue extension. You
can almost imagine the wind sort of sealing the flue opening.

Now picture wind gliding across a sloped crown and hitting the wall of a
2" extension. The wind is forced upward instead of flowing across the
opening.- Hide quoted text -

- Show quoted text -
extension helps screw chimney cap on......... try to do it with "
flush flue"

But is that why it's code?



I found lot's of references to the flue being 2" above the crown but
none of them cite specific code references, other than "Check your local
code". This site says it the best, but I've included a few other
references for your reading pleasure.

ftp://imgs.ebuild.com/woc/M930413.pdf

Make sure the flue liner extends at least 2 inches beyond the top of the
chimney, but check local building codes for the requirements in your
area. This extension permits attachment of a rain hood and keeps ice and
snow that accumulates on the crown from dropping into the flue. To avoid
excessive cooling and condensation, don’t project the flue liner more
than 6 inches above the crown.

http://www.chimneylinerdepot.com/lan...ey-anatomy.asp

Most flue liners extend above the chimney crown at least two inches. In
some chimneys the liner may extend higher than this depending on local
building codes.

http://www.diychatroom.com/showthread.php?t=3970

The crown should slope away from the flue liner, the flue liner should
protrude at least 4" from the crown and the joint between the flue liner
and the cap should be sealed with a flexible joint sealer.
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Default Flue extending beyond crown on a chimney

Thanks


"DerbyDad03" wrote in message
...
Sheldon wrote:
I cannot find anything on the web that indicates that the flue has to
extend 2" beyond the crown.

The chimney has to be 3' beyond the portion of the roof where it emerges.
The chimney also has to be 2' higher than anything that is within 10'.


"DerbyDad03" wrote in message
...
wrote:
On Sep 13, 1:07 pm, DerbyDad03 wrote:
Sheldon wrote:
Why are so many chimneys built with the flue(so) that extend above
the
crown?
For Looks?
To improve the chimney draw? I would think the small increase in
height
would make little or no difference
To allow the chimney to meet code? I would think the chimney could
just
have been built at the correct height in the first place.
Sheldon
AFAIK, the code requirement in most areas is that the flue must extend
at least 2" above the crown. YMMV

Picture wind gliding across a sloped crown with no flue extension. You
can almost imagine the wind sort of sealing the flue opening.

Now picture wind gliding across a sloped crown and hitting the wall of
a
2" extension. The wind is forced upward instead of flowing across the
opening.- Hide quoted text -

- Show quoted text -
extension helps screw chimney cap on......... try to do it with "
flush flue"
But is that why it's code?



I found lot's of references to the flue being 2" above the crown but none
of them cite specific code references, other than "Check your local code".
This site says it the best, but I've included a few other references for
your reading pleasure.

ftp://imgs.ebuild.com/woc/M930413.pdf

Make sure the flue liner extends at least 2 inches beyond the top of the
chimney, but check local building codes for the requirements in your area.
This extension permits attachment of a rain hood and keeps ice and snow
that accumulates on the crown from dropping into the flue. To avoid
excessive cooling and condensation, don’t project the flue liner more than
6 inches above the crown.

http://www.chimneylinerdepot.com/lan...ey-anatomy.asp

Most flue liners extend above the chimney crown at least two inches. In
some chimneys the liner may extend higher than this depending on local
building codes.

http://www.diychatroom.com/showthread.php?t=3970

The crown should slope away from the flue liner, the flue liner should
protrude at least 4" from the crown and the joint between the flue liner
and the cap should be sealed with a flexible joint sealer.



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Default Flue extending beyond crown on a chimney

On Sep 13, 7:07*pm, "Sheldon" wrote:
Thanks

"DerbyDad03" wrote in message

...



Sheldon wrote:
I cannot find anything on the web that indicates that the flue has to
extend 2" beyond the crown.


The chimney has to be 3' beyond the portion of the roof where it emerges.
The chimney also has to be 2' higher than anything that is within 10'.


"DerbyDad03" wrote in message
...
wrote:
On Sep 13, 1:07 pm, DerbyDad03 wrote:
Sheldon wrote:
Why are so many chimneys built with the flue(so) that extend above
the
crown?
For Looks?
To improve the chimney draw? *I would think the small increase in
height
would make little or no difference
To allow the chimney to meet code? *I would think the chimney could
just
have been built at the correct height in the first place.
Sheldon
AFAIK, the code requirement in most areas is that the flue must extend
at least 2" above the crown. YMMV


Picture wind gliding across a sloped crown with no flue extension. You
can almost imagine the wind sort of sealing the flue opening.


Now picture wind gliding across a sloped crown and hitting the wall of
a
2" extension. The wind is forced upward instead of flowing across the
opening.- Hide quoted text -


- Show quoted text -
extension helps screw chimney cap on......... try to do it with "
flush flue"
But is that why it's code?


I found lot's of references to the flue being 2" above the crown but none
of them cite specific code references, other than "Check your local code".
This site says it the best, but I've included a few other references for
your reading pleasure.


ftp://imgs.ebuild.com/woc/M930413.pdf


Make sure the flue liner extends at least 2 inches beyond the top of the
chimney, but check local building codes for the requirements in your area.
This extension permits attachment of a rain hood and keeps ice and snow
that accumulates on the crown from dropping into the flue. To avoid
excessive cooling and condensation, don’t project the flue liner more than
6 inches above the crown.


http://www.chimneylinerdepot.com/lan...ey-anatomy.asp


Most flue liners extend above the chimney crown at least two inches. In
some chimneys the liner may extend higher than this depending on local
building codes.


http://www.diychatroom.com/showthread.php?t=3970


The crown should slope away from the flue liner, the flue liner should
protrude at least 4" from the crown and the joint between the flue liner
and the cap should be sealed with a flexible joint sealer.- Hide quoted text -


- Show quoted text -


In our area it must extend 4inches or more 6 is the norm
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Default Flue extending beyond crown on a chimney


The building code for my state does not specify that it must extend beyond
the crown, unless the crown is considered an "enclosing wall". Even then
there is no dimension is specified. Diagrams in the code do no specify it
either.


Flue lining (installation): Flue liners shall extend from a point not less
than eight inches (203 mm) below the lowest inlet or as otherwise required
by 248 CMR or 527 CMR if applicable, or, in the case of fireplaces, from the
top of the smoke chamber, to a point above the enclosing walls.



"jim" wrote in message
...
On Sep 13, 7:07 pm, "Sheldon" wrote:
Thanks

"DerbyDad03" wrote in message

...



Sheldon wrote:
I cannot find anything on the web that indicates that the flue has to
extend 2" beyond the crown.


The chimney has to be 3' beyond the portion of the roof where it
emerges.
The chimney also has to be 2' higher than anything that is within 10'.


"DerbyDad03" wrote in message
...
wrote:
On Sep 13, 1:07 pm, DerbyDad03 wrote:
Sheldon wrote:
Why are so many chimneys built with the flue(so) that extend above
the
crown?
For Looks?
To improve the chimney draw? I would think the small increase in
height
would make little or no difference
To allow the chimney to meet code? I would think the chimney could
just
have been built at the correct height in the first place.
Sheldon
AFAIK, the code requirement in most areas is that the flue must
extend
at least 2" above the crown. YMMV


Picture wind gliding across a sloped crown with no flue extension.
You
can almost imagine the wind sort of sealing the flue opening.


Now picture wind gliding across a sloped crown and hitting the wall
of
a
2" extension. The wind is forced upward instead of flowing across
the
opening.- Hide quoted text -


- Show quoted text -
extension helps screw chimney cap on......... try to do it with "
flush flue"
But is that why it's code?


I found lot's of references to the flue being 2" above the crown but
none
of them cite specific code references, other than "Check your local
code".
This site says it the best, but I've included a few other references for
your reading pleasure.


ftp://imgs.ebuild.com/woc/M930413.pdf


Make sure the flue liner extends at least 2 inches beyond the top of the
chimney, but check local building codes for the requirements in your
area.
This extension permits attachment of a rain hood and keeps ice and snow
that accumulates on the crown from dropping into the flue. To avoid
excessive cooling and condensation, don’t project the flue liner more
than
6 inches above the crown.


http://www.chimneylinerdepot.com/lan...ey-anatomy.asp


Most flue liners extend above the chimney crown at least two inches. In
some chimneys the liner may extend higher than this depending on local
building codes.


http://www.diychatroom.com/showthread.php?t=3970


The crown should slope away from the flue liner, the flue liner should
protrude at least 4" from the crown and the joint between the flue liner
and the cap should be sealed with a flexible joint sealer.- Hide quoted
text -


- Show quoted text -


In our area it must extend 4inches or more 6 is the norm


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