Wbere does the rain go?


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Old 08-11-14, 05:04 AM
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Wbere does the rain go?

When rain gets driven into a flue, under a cap or if you didn't have a cap... where does the water go?

For example I do not have a cleanout in my basement for my chimney. It has a terra cotta liner. Its for gas appliance, not wood. Where does the water go?
 
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Old 08-11-14, 05:53 AM
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While not a lot of water, rain can/will go down the flue. Since there isn't a cleanout, I'd definitely install a chimney cap. Does the clay liner protrude above the top of the chimney? do you know the size?
 
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Old 08-11-14, 06:29 AM
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Its a 6x6 clay liner. It does not extend above the crown. I do have a cap.

The crown does not overhang the side of the chimney as well.... its flush with the chimney walls.
 
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Old 08-11-14, 06:31 AM
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Does the cap fit poorly or are you just referring to the small amount of rain that occasionally enters thru the openings in the cap? If the latter, it's probably nothing to worry about.
 
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Old 08-11-14, 07:15 AM
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The cap doesn't fit poorly but it one of those kind that have the heavy gauge hardware cloth around it. Rain could technically get in easily.

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That's the one I have, my clay liner does not extend up so instead its mounted with feet that go inside the liner.

So what happens then when water gets in? It just wicks into the brick? Or falls and collects in the bottom?

Is it possible for rain that enters the flue to show up on the outside of the brick say in the attic?
 
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Old 08-11-14, 07:47 AM
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Water that falls into an open flue is going to lay in the bottom until it evaporates, but, with a cap, I would not give whatever wind driven rain that sneaks in there a second thought. The only way that water would get through the flue, through the brick, and into the attic would be if you had damage to the chimney, in which case I personally would be as or more worried about the CO entering the living quarters. I really don't see any concerns, so far. However, I would address the crown being flush with the flue, not overhanging the brick, and, if applicable, not being sloped away from the flue. Water holds tension on surfaces, so, without a proper overhang, can seep between the crown and the brick, which then could allow it to get into the attic, as well as other potential problems such as causing bricks to freeze and crack.
 
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Old 08-11-14, 09:37 AM
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I would address the crown being flush with the flue, not overhanging the brick,
Yesits much like the one in the photo, other than it has a stone vaneer covering over the brick. The crown and the vaneer and flush... there is no overhang.

At this point, how would that be corrected short of redoing the entire crown?
 
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Old 08-11-14, 11:45 AM
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I do not know of a solution other than removing the existing crown and pouring a new one. The crown should be about 2" thick, concrete, not mortar, should overhang the top course of bricks by a couple of inches, and should slope away from the flue, with something, even if 1/2" or so of flue extending above it. I like to include a lip on the bottom outside edge of it, so that the water will break and fall to the roof rather than following the bottom side of the crown back to the brick, and usually wrap the flue with sill seal or something similar, so that the concrete won't crack as it shrinks around the flue.
 
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Old 08-11-14, 01:02 PM
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thanks for the good info.

So its completely wrong not having the over hang and not having any clay liner extending out of the crown?

There is a slope but you saying without the overhang it goes right down the sides and without the extention of the liner it drops down the flue.
 
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Old 08-11-14, 01:59 PM
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May not be correct but my chimney doesn't have an overhang and I haven't noticed any issues with it over the last 20+ yrs. It would be better if the top of the flue was higher so rain would be less likely to be blown under the cap.
 
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Old 08-11-14, 02:19 PM
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I said "should". Not going to go so far as to say "completely wrong", because, just like Mark's, there are a lot of chimneys out there on which the crown does not overhang the bricks, in fact probably as many of one as the other. If you look at it closely at it though, you will probably see places where water could follow the crown around between it and the bricks, and, if enough of it gets in there, it can freeze. As for the flue, I do not know if there is a standard, but it sounded like you are concerned about water getting down the chimney, and that is one place where it obviously could, particularly if the crown is relatively flat.
 
 

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