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Old 12-16-2010, 12:13 PM   #16
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Chimney leaking


Quote:
Originally Posted by stuart45 View Post
All the chimneys like yours that I've built were cavity walls ( brick/2-4inch air gap/brick) so water could not reach the inner wall.
There could be a design fault with the stack.
I was reading through this again and must have missed this part the first time around. Since I'm not overly familiar with this portion of construction, could you help me out here?

Is what you mention above the standard way to build a chimney? In other words, 2x4inch brick, air space, and then 2x4 inch brick inside that brick?

I know that's not how this was constructed in most areas. it's just the 2x4 inch brick, plus the necessary work for the flue, firebox, smoke chamber, etc... In other words, I'm near 100% positive that, above the smoke chamber, it's just 2"x4" brick all the way up (at least to the rake, where they may have made some adjustments there).

I do have a question on the above though. If you have a 8" foundation base, and you lay 2"x4" brick and then air space (what's standard air gap?), and another 2"x4" brick, you're going to exceed the 8" foundation base. Do you use an angle iron to get around this? Do you lay the inner brick on it's shorter side to only take up 2"?

Quote:
Originally Posted by jomama45
From what I can see from the one pic, this is anything but a typically constructed chimney chase.
As I mentioned above, I'm not overly familiar with proper chimney/fireplace construction. Would you be able to elaborate as to why this doesn't appear to be a typically constructed chimney chase?* And, would you be able to explain what a typical constructed chimney chase would consist of? Any information would be greatly appreciated.

* What is a "chase"? Is that simply the brick exterior of the chimney going up?

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Old 12-16-2010, 01:53 PM   #17
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I might have confused the issue here. That is the standard method in the UK where damp penetration is a major problem with buildings. The foundations are usually at least 2 ft wide in a trench and the cavity walls are brought up from below ground level.
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Jomama will know better than me on the correct method of chimney construction over your side of the Pond. I am interested to see the differences in construction.
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Old 12-16-2010, 11:21 PM   #18
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Chimney leaking


Long day & it's too late now, but i promise that I'll post an in-depth description & explanation in the next few days.........................

And the more I look at the pics, the more I find myself asking WTF?????
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Old 12-17-2010, 06:56 AM   #19
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That's a WHOLE lotta' water!

1) Water (especially wind-driven rain) can pass through brick veneer and penetrate to the interior if the walls detailing is incorrect:



but in my experience it's not likely THAT much water is coming though the masonry itself, though if you want to be certain the wall is not highly absorbent you can get someone to perform a RILEM test.

2) It's tough to properly flash that uphill junction at that chimney projection at the rake (we just has a long discussion of this issue here recently, but I can't find the thread at then moment) - and it's certainly one suspect. My preference for that flashing is a "half cricket" which deflects ALL water around the chimney to the side opposite the rake, though most posters here feel that's overkill. If you are spilling water over the rake edge, it obviously has the potential to enter anywhere along the length of the chimney below at its intersection with the cladding.

3) Without seeing the top of the chimney, there is no way to know if the detailing there is correct, and this is a potential source of significant water entry.
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Old 12-17-2010, 09:20 AM   #20
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jomama... thank you. I look forward to your post. I have a meeting with my G.C. tomorrow morning, so I'd like to be as informed as possible before that talk.

Quote:
Originally Posted by Michael Thomas
1) Water (especially wind-driven rain) can pass through brick veneer and penetrate to the interior if the walls detailing is incorrect:
I've heard this as well. Just so we're on the same page, this is not a brick veneer, but a solid brick chimney. I went and talked to the gentleman we bought the brick from and he truly does not believe this would be water coming through the brick. It's a high end Belden brick, which he believes should not experience this type of problem.

The rain that came through WAS heavy, and I mean really heavy, wind driven sideways rain. The side of the house with the chimney was the side that was experiencing the brunt of this rain. While it was raining all day, the sideways rain was occurring for about an an hour and a half to two hours before I noticed the water (though, I readily admit that it could have started earlier in the day, as I was working in an entirely different portion of the house most of the day).

Also, during the construction of the chimney, when the top was still fully open, we never saw water like this. Though, we never had a storm quite as bad as the one this past weekend.

Quote:
Originally Posted by Michael Thomas
It's tough to properly flash that uphill junction at that chimney projection at the rake (we just has a long discussion of this issue here recently, but I can't find the thread at then moment) - and it's certainly one suspect. My preference for that flashing is a "half cricket" which deflects ALL water around the chimney to the side opposite the rake, though most posters here feel that's overkill. If you are spilling water over the rake edge, it obviously has the potential to enter anywhere along the length of the chimney below at its intersection with the cladding.
Agreed. I had discussions about this exact particular area prior to the having this issue. However, we opted away from the half-cricket, since the majority of the fireplace is outside the rake.

The main issue, though, is that even if there was an issue with the flashing, or even the caulking along the intersection of the chimney with the sheathing, it would not have manifested itself in this type of leak.

Let me explain what I mean by this. From a construction stand point, the brick comes out two feet from the sheathing, across 5 feet, and then back in two feet towards the sheathing. The areas of the brick that were wet (soaked) were the entire exterior 5 feet, and maybe a foot in on each side. The brick along the sheathing was completely bone dry. If there was an issue with the flashing on the roof over the rake, or along the sheathing, I'm fairly certain that the brick along the sheathing would have been soaked as well.

Quote:
Originally Posted by Michael Thomas
3) Without seeing the top of the chimney, there is no way to know if the detailing there is correct, and this is a potential source of significant water entry.
I'm going to attempt to get up there this weekend to take pictures. It's just difficult right now, as I no longer have the mechanical lift on site, and with the temps in the low teens right now, it's tough to get on the roof as the shingles are often iced over.

I can explain that the top of the chimney has two rows of bricks that come out slightly further than all the rows below them, creating a small step out. The chimney has a cement/mortar cap up to the two flues, and there is a stainless steel cap covering the two flues. The stainless steel cap does not cover the entirety of the cement/mortar cap. I confirmed that the screws that were used to install the stainless steel flue cap were caulked and sealed.

The only thing I can see is that the cement/mortar cap is not angled the way I think it should be done. There 'is' an angle, but it's not as steep as I think it should be to create the proper run off. However, since the flue's were completely bone dry, I really don't necessarily see that as the problem.

One thing I know is that the mortar joints are significantly more porous than the brick itself. So, if this is an issue with the mortar joints and not the brick, is there a likelihood it's due to an improper type of mortar?

I mean, I keep hearing about sealing the chimney, which I'm obviously going to have to do. However, I know tons of large buildings in my area that are all brick and mortar, and I know they did not seal them. I cannot believe that they're experiencing this type of water intrusion from driving rain.

Again.. thank you guys for your help and information. This is an area of construction where I'm fairly weak and even google searches don't necessarily provide quite the information I'm looking for.
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Old 12-17-2010, 11:16 AM   #21
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Re: chimney caps, take a look here:



- Chimney Caps To Last A Lifetime

WRT the exit of the water at the junction of the chimney with the foundation, is there visible evidence of a through wall flashing at this location? Water sometimes either travels along such flashings to exit at a point some distance horizontally for the vertical position of leak, or spreads out from a narrow stream of water at the interior and out along the flashing.

Do you have any pictures of the chimney during construction, or a clear recollection of a cross section view of the chimney above the foundation? How to the construction drawings indicate the chimney should have been built?
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Old 12-17-2010, 11:22 AM   #22
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BTW, I'd very much appreciate it if you would keep us informed on your progress and the eventual diagnosis and solution, one of the most frustrating experiences here it to follow the progress on one of these investigations for a few days or weeks, and then never learn the actual problem and the successful fix so we can help the next person with a similar problem.
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Old 12-17-2010, 12:02 PM   #23
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Chimney leaking


Quote:
Originally Posted by Michael Thomas
Re: chimney caps, take a look here:
I can say that the chimney cap we have is not quite like that. Basically, at the top of the chimney, they created the 2 inch spacing from the main chimney with brick. So the top two rows of brick go out 2" further than the main stack. Then, the cement/mortar cap goes directly over those top of the top row of those two rows of brick. The cement cap does not overhang the brick.

NOTE: In the pdf link you provided, it's created like the second picture (1976-1985).

Quote:
Originally Posted by Michael Thomas
WRT the exit of the water at the junction of the chimney with the foundation, is there visible evidence of a through wall flashing at this location? Water sometimes either travels along such flashings to exit at a point some distance horizontally for the vertical position of leak, or spreads out from a narrow stream of water at the interior and out along the flashing.
I don't remember any kind of flashing where the brick meets the foundation. I believe he just bonded the brick directly to the foundation. You can see this juncture point in the first picture (with all the water). I know there is nothing visible in the interior or exterior.

Quote:
Originally Posted by Michael Thomas
Do you have any pictures of the chimney during construction, or a clear recollection of a cross section view of the chimney above the foundation? How to the construction drawings indicate the chimney should have been built?
Unfortunately, I have no pictures like this. I have some idea of how it was built, so I can potentially answer any questions you may have.

Quote:
Originally Posted by Michael Thomas
BTW, I'd very much appreciate it if you would keep us informed on your progress and the eventual diagnosis and solution, one of the most frustrating experiences here it to follow the progress on one of these investigations for a few days or weeks, and then never learn the actual problem and the successful fix so we can help the next person with a similar problem.
I will definitely try to do that. The only current 'solution' I have right now is to seal the brick and mortar. Unfortunately, that cannot be done until March or April, as it's currently in the low 20's to teen's and, from what I have read, most sealers require a minimum of 40 degree temperatures.

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Old 12-18-2010, 08:23 AM   #24
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There's any number of things that I notice just from those three pictures that I would consider non-typical construction. Some may just be due to the fact that different markets use different approaches, but there certainly a few issues, at the very minimum, that are less than ideal for successful masonry construction. Regardless, something(s) obviously wrong if the chimneys leaking this bad. Even with the amount of rain you're explaining, there's no reason this should be leaking inward. Here's a few observations: (although some may be a stretch because I can't see every detail in the pics)

- At the base of the wall, there doesn't appear to be any dropped brickledge. In my experience, w/o the brickledge, 9 times out of 10 any water inside the cavity will have the tenancy to leak inward. If I were to have constructed the chimney, I would have request a 4" deep by 8" high pocket formed into the top of the foundation wall at the base. Better yet, I would have requested a 10" wide wall through the chimney like the rest of the house, and the wall would have gone the full 9' high. The below grade would have been 10" wide, and everything above grade would have been 6" wide, leaving a 4" brick ledge. It's just the most efficient way to construct it.

- I see no evidence of weeps or flashing at the base.

- While the interior firebox looks alright, I can spot a few questionable things. Where's the wall ties, as it's obvious by looking at the firebrick floor that the FP surround will be full veneer. Is there at least 1" clearance to combustables at the sides & top??? Doesn't quite look like it. And why is the wall sheeted behind the FP? Maybe it's just the way we do it here, but it would have been easier on the mason, and likely made a better job all together, if the studs where left out between the massive shoulders until the chimney was done. (maybe they were now that I think of it?)

- I can't tell from the pic, but the cap certainly should overhang ALL brick by at least 2", and look exactly like Michael's link. Corbelling the top two courses isn't enough to keep water dripping past the brick.

- How a mason can properly detail and construct a chimney of that size without using concrete block (CMU) is beyond me. Obviously, one can't. The inner wall (back wall) should be made of a material that's far more rigid & strong than the veneer that's attaching to it. It should also be waterproof, which isn't easy to do with brick. Not to mention, why in the world would someone lay all those extra brick when block are stronger, faster, offer better water resistance, can be easily re-enforced if necessary, far cheaper, etc.... It makes no sense to me that the entire chimney was built with two wythe construction.

- I think that the roof/chimney connection could certainly be the source as well. In that kind of height, water can move horizontally pretty far before far before it exits. I would run a hose right above that flashing for a period of time (when the weather allows of course) to see if you can replicate the leaking again.

- DO NOT seal the brick until you are 100% sure you have found the leak. I probably wouldn't seal the brick at all if it can be helped. Seeing you already have an avenue to talk to the Belden, I would certainly recommend calling them to first as well to verify that their brick can be sealed. Picking up spalled brick faces in spring just so you can mow the lawn is not a situation you want to be in.

Here's a link as to how conventional masonry/cavity walls are meant to be constructed. Page 5 has the most pertinent illustrations. Note that they show a double wythe wall detail with integrated flashing as well in the link.

http://www.gobrick.com/html/frmset_thnt.htm
(on edit, go to article 7, Dec 2005)

Good luck, and certainly let us know what's discovered after meeting w/ the builder.
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Old 12-18-2010, 09:50 AM   #25
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Great info and an interesting link Joe. Sealer is a last resort to poor construction.
Here's an example of a more modern method of constructing a chimney here. They used to be solid brickwork, but now the jambs are usually voids.
Chimney leaking-php5yavomam.jpg
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Old 12-18-2010, 10:21 AM   #26
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Yup... IMO we really need:

1) To know more about the chimney's construction.

2) A good look at the top of the chimney

before we can get much further.

BTW, I an NOT suggesting the OP get up on that roof in the winter, or at any other time, unless they are certain it is safe for them to do so.

Given that there is this much water penetration, if this chimney is serving only the fireplace, I would suggest that one obvious diagnostic is to have someone get up there and (assuming they do not observe some obvious mode of water entry at the cap) after having made certain (via signage at the chimney or some other method) that no one will attempt to use the fireplace tarp off top 2-3 feet of the chimney and see if the water intrusion stops, .
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Old 12-18-2010, 06:32 PM   #27
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Quote:
Originally Posted by stuart45 View Post
Great info and an interesting link Joe. Sealer is a last resort to poor construction.
Here's an example of a more modern method of constructing a chimney here. They used to be solid brickwork, but now the jambs are usually voids.
Attachment 27810
Actually fairly similar Stu.
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Old 12-18-2010, 07:30 PM   #28
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Hi!

An interesting problem that you have, one that has caught my attention!

First comment, just to set the record straight - 'yes' the brickwork will let penetrating rainwater in, and in torrents in the conditions that you have described. The reason you don't see the damp when looking up the flue is that the damp is between the brickwork and the external face of the flue.

One thing you seem to be short on is lead dpc's/trays and weep holes especially with such a large exposed flank.

I have hopefully managed to attach a file issued by zurich insurance which provides a best practice method for constructing chimneys and you may wish to measure your construction detail against this standard.

I hope this information is of some assistance.
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File Type: pdf zurich detail small.pdf (82.4 KB, 232 views)
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Old 12-18-2010, 08:34 PM   #29
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I've always thought that the English practice of through-wall flashings at chimneys is a good idea, but you never see it (at least I've never seen it) done in the US.
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Old 12-19-2010, 07:45 AM   #30
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Hi Michael

To be honest you do not see this level of detail on modern chimney stacks as the design generally speaking follows the principles of the diagram provided by Stuart45 on discussion thread 25. Having the cavity wall construction does away with the need for the intermediate flashings, but you would still retain the 3 trays shown in the 'zurich detailed design' above roof level.

Below the roof line the rainwater would enter the cavity and flow down the inside face of the external brickwork where it would either evaporate or travel down to below dpc level where the cavity will be filled with sharp sand and cement and camfered to a fall to the outside of the building below dpc level and weep holes would allow the water to escape where it can do no harm.

The only problem comes where the cavity has not been kept clear of debri and mortar snots and in some situations insulation material which then allows the rainwater to breach the cavity and cause damp problems inside the building (which is not that uncommon in the UK).

The full extent of AgentWs problems is shown in the first photograph shown on AgentW discussion thread. The photograph shows the trapped rainwater perculating out at base level of the chimney stack between the render and the face brickwork, which is solely caused by the volume and head height of rainwater trapped behind the face brickwork and the internal flue.
Water will always seek the path of least resistance and the flue being of a denser material than the brickwork means that the rainwater will eventually force itself out through the brickwork, the render at low level then provides a barrier and the rainwater perculates out as shown in the photograph.

This does not mean that rainwater will not penetrate further up the chimney stack as it meanders its way to the base of the chimney stack as is evidenced by the damp problems at first floor, as already mentioned water will always seek the path of least resistance.

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