Chimney Chatter - Leaking chimney

amk
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Leaking chimney
« Thread Started on Apr 27, 2010, 7:48am »

Five months ago, had new concrete chimney crown installed, with a two-flue stainless steel chimney cap. The chimney cap seems to have been installed into the concrete, or looks that way from the street. Now I still have rain coming into my fireplace and furnace flues when heavy rain blows sideways. My roofer tells me the rain is collecting inside the base of the stainless steel cap (sort like a well is formed inside the chimney cap base) and eventually overflows down into the flues. Doesn't the stainless steel cap allow for drainage? Should there be drainage holes? Can this be corrected?

« Last Edit: Apr 27, 2010, 7:50am by amk »

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Ray
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Re: Leaking chimney
« Reply #1 on Apr 27, 2010, 8:32am »

Apr 27, 2010, 7:48am, amk wrote:

Five months ago, had new concrete chimney crown installed, with a two-flue stainless steel chimney cap. The chimney cap seems to have been installed into the concrete, or looks that way from the street. Now I still have rain coming into my fireplace and furnace flues when heavy rain blows sideways. My roofer tells me the rain is collecting inside the base of the stainless steel cap (sort like a well is formed inside the chimney cap base) and eventually overflows down into the flues. Doesn't the stainless steel cap allow for drainage? Should there be drainage holes? Can this be corrected?

The best way to repair a chimney crown is to apply a "flex crown" over the existing crown. This allows flexible material to prevent water to enter the crown when the weather causes the crown to expand and contract with temp change. Many chimney people will tear off the old crown and rebuild a new crown. This sets up for the same problem. Just like sidewalks, the concrete or mortar will crack. Water leaks down these cracks.

As far as your multi-flue chimney cap. It should have an angled top to drain water away from the crown. If the crown is angled back to the flue, this can be a problem. If the crown is angled, you might want apply "flex crown" to the top to help water proof the crown.

Check more of our forum threads and find one of leaking chimneys. You will find that the exterior bricks might be soaking water from the outside and down the flue. Also check the flashing between the chimney and roof. Bricks can be waterproofed with waterproofing materials. Hope this helped.

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amk
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Re: Leaking chimney
« Reply #2 on Apr 28, 2010, 7:06am »

Thanks, Ray. But if rain is blowing into the stainless steel chimney cap through the perforated openings and then accumulating inside and eventually spilling over into the flues, what is the best way to correct this? Is it possible to just drill drain holes or weep holes around the bottom of the stainless steel cap? Since the new stainless steel cap has a solid base on the lower half and is perforated on the upper half, it seems likely that blowing rain will always enter through the perforated upper section and pool inside the lower section. Does that happen often?

« Last Edit: Apr 28, 2010, 7:08am by amk »

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Ray
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Re: Leaking chimney
« Reply #3 on Apr 29, 2010, 9:33pm »

Apr 28, 2010, 7:06am, amk wrote:

Thanks, Ray. But if rain is blowing into the stainless steel chimney cap through the perforated openings and then accumulating inside and eventually spilling over into the flues, what is the best way to correct this? Is it possible to just drill drain holes or weep holes around the bottom of the stainless steel cap? Since the new stainless steel cap has a solid base on the lower half and is perforated on the upper half, it seems likely that blowing rain will always enter through the perforated upper section and pool inside the lower section. Does that happen often?

Usually, this does not happen. But if this is causing the problem, one solution would be to install a lock top damper. Check our thread under dampers. Basically, the damper is at the top of the chimney cap. When the damper is pulled closed, it lowers to the bottom of the chimney cap and produces an air tight seal. Thus, if water entered the side holes of the cap, it could still not enter down the closed flue. Usually, only sideward wind rain will cause the problem you are talking about and still, it usually isn't that much water.

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amk
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Re: Leaking chimney
« Reply #4 on Apr 30, 2010, 11:33am »

Thanks. I've been looking into locking dampers for the fireplace. But not sure they will work on my furnace flue. For the fireplace I would have to manually open the damper. But for the furnace? With all the stormy weather we'ved been having lately, side-ways driving rain is becoming very common. Just might have the drainage holes drilled into the chimney cap as a first step.

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stacyalmando
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Re: Leaking chimney
« Reply #5 on Jul 31, 2010, 2:08am »

Sometimes you think you have a roof leak when in fact the roof is fine. Chimney crowns can develop cracks. The inside surface of the chimney gets discolored or the plaster bubbles. You think a roof leak is the cause.

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electric fireplaces

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Re: Leaking chimney
« Reply #6 on Sept 26, 2010, 9:23am »

I have a leaking (water) chimney. With heavy rain and wind the water runs down the front of my fireplace and also into the cleanout in the basement. I had a mason with 35+ years of experience replace the chimeny using new bricks & new lead flashing. The shingles were replaced at the same time too. Leaking problem has continued! I have installed custom made caps to completely seal both flues and applied two coats (a week apart) of Pro Flex sealant on the concrete top and on the bricks. Still leaking. Two experienced masons have looked at th chimney and can't figure it out. The water comes out tru the brick (in the attic) a few inches beolw the roof line and runs down the surface. The roof edge, around the chimney, is dry.

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Ray
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Re: Leaking chimney
« Reply #7 on Sept 27, 2010, 11:54am »

Apr 27, 2010, 7:48am, amk wrote:

Five months ago, had new concrete chimney crown installed, with a two-flue stainless steel chimney cap. The chimney cap seems to have been installed into the concrete, or looks that way from the street. Now I still have rain coming into my fireplace and furnace flues when heavy rain blows sideways. My roofer tells me the rain is collecting inside the base of the stainless steel cap (sort like a well is formed inside the chimney cap base) and eventually overflows down into the flues. Doesn't the stainless steel cap allow for drainage? Should there be drainage holes? Can this be corrected?

The flue should extend at least 2 inches above the chimney crown. This keeps water from going down the flue when it overflows from a heavy rain. The second reason is that brick is pourous and when sideways rain hits it, the brick soaks up water and eventually leaks down the chimney. The crown was likely replaced but was likely very thin and thus water leaks down the chimney because mortar is pourous.

You likely need your flue extended, crown repaired with flexible crown and the brick on the chimney water sealed. You might try the water sealing first to see if it solves your problem. Other issues might be that you need a chimney cricket or chimney flashing properly installed. Hope this helps.

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