chimney leaks & masonry fixes

[peter_nesbeitt]

Hi folks,

Some questions about the best way to deal with a leaky chimney / roof area. I'm hoping there are some knowledgeable masons / roofers / home-owners out there with good ideas...

Background:

I have an 11-year old 2-story colonial with a chimney at one end of the house, slightly off-center. For the past 8 years, there have been on-again, off-again problems with water in the attic where the edge of the roof meets the chimney. Not dripping water, but wet plywood causing visible stains, especially after a long rain. The attic is well-ventilated, so it's not interior moisture.

I've had various roofers and masons try various fixes over the years:

1 - Had the counterflashing re-done (cut out the old with a diamond saw, put in new counterflashing). It's not interleaved with the shingles, which I think may be a problem.

2 - Had the chimney sealed about 4 years ago with a siloxane compound in spring.

3 - Had caulking applied between the chimney and the siding of the house.

4 - Had a metal chimney cap put on above the flues.

5 - Had the shingles and step flashing around the chimney re-done, 3 times (!). The first 2 times, the folks turned out to be not so great. They used a ton of silicone, even under the shingles, and basically made a mess of things. The 3rd roofer, recently, was pretty good; seemed a very experienced, competent fellow. He ripped up the shingles; put a new ice-and-water barrier in that area and around the chimney (making sure to overlap it with the bottom course of shingles); and put in new step flashing. This helped -- but even after a moderate rain, there was still a 1" wet spot in the attic, a little above where the bottom corner of the chimney meets the house.

And here are the recent recommendations I've had from various masons / roofers / chimney sweeps:

1 - Re-do the flashing (again). 2 - Re-seal the chimney (again) (with ChimneySaver, or a Umaco compound). 3 - Put a thicker concrete crown on top of the chimney, and extend the flues a couple inches above the crown (right now, they're flush with the top of what looks like a fairly thin mortar crown). 4 - Tear down and re-build the chimney above the roof-line; do selective re-pointing; and then do #1-3 above. (This option would cost about $3200 - $4200.)

So (finally), here are my questions:

1 - In general... which of the above sounds like a reasonable approach? Any other thoughts?

2 - Does the price on option #4 sound right? It seems a lot of money... but none of the other fixes have worked.

3 - On the masonry web sites I've read, the usual recommendation is to extend a concrete crown a couple inches past the edge of the brick; to put an expansion joint around the flues; and ideally to flash the flues. All the masons I've talked with, even the experienced, competent-seeming ones, dismiss these ideas. How important is it to do this?

4 - Near the top of the chimney, it's corbeled out and back again in a "beehive" (i.e., 3 successive courses of brick out, then 3 back, then up to the crown). One mason would prefer to re-build it without corbeling into a beehive. Does it matter, from a water absorption perspective?

5 - How important is it that the flues don't extend past the crown right now?

At least in this area, it seems that there aren't that many masons who (a) are experienced and competent, and (b) return phone calls and show up. I've found one or two (I think), but before spending even more $$$ on this issue, I'd like to get the wisdom of folks out there (even after having read a lot of the past threads on chimneys & masonry).

Thanks!

Peter

[William.Deans]

I have a slightly different take on the way you should approach this. Call as many reputable people as you have time for and go with the lowest bidder who will give you a five year guarantee on parts and labor with a certain number of days to respond in the event it starts leaking again. If they don't respond you get three bidders and send them the bill. Call them back when it leaks again and remind them. Take a photo of the wet spot and be sure that you note an area of the roof in in the photograph in which if water is located you both agree in advance that the cause is assumed to be the chimney.

Good luck!

[Moe]

wrote

Peter,

I didn't see anyone discuss with you, leak detection. All the contractors you have talked with, have given you solutions to an unknown problem!

You need to find someone to determine the source of the problem. Then solutions can be given.

1. Hire someone which does "Thermal infrared" inspections. Do be prepared to spend a couple-few hundred dollars for this service. Some thermal infrared inspectors will _not_ give you solutions.

OR

1. Hire a roofer which specializes in "leak detections". Basically, someone will get into the attic, the other person on the roof to work a flowing hose from top to bottom. Most have 2way communication systems, so there isn't a lot of yelling going on. Again, be prepared to spend a couple-few hundred dollars for this service.

Only once the source of the problem is determined, can a solution be recommended.

Good luck!

[trader4]

I agree with that approach. Without knowing exactly what the cause is, you could spend a lot of money fixing things that aren't the problem. With a water hose and someone watching in the attic, you need to start at the lowest point in question, then very slowly work up the chimney/roof interface and then on up the chimney itself. Allow sufficient time in each area for the water to appear. If you go too fast, you may see water appear, but it could be from a spot you were at two minutes ago, not where you are at now. After figuring out where it's coming from, repeat the test another day, focusing on only the identifed area to verify.

[DanG]

You have had a long term problem. I think the first thing to do would be to eliminate what ain't broke. Right now, you don't know whether it is the chimney cap allowing moisture into the brick, brick and mortar leaking, roof/flashing problem.

Take a garden hose, be very careful about where you direct the water. The water does not and should not have a lot of pressure, we are not trying to INJECT the water. Start as low and far down as possible in the affected area. Use bricks or blocks to control the water direction. Allow the water to flood at least 30 minutes before moving the hose slightly higher. Test the roof shingles first, all the way around. Next test the flashing. Next test the brick faces. Test the cap. If you are getting conflicting information, you may need to allow it to dry out and retest. I am a bit surprised that none of your so called experts have already suggested it. Yes, it takes time; but I think you will be far ahead of where you are now.

Sooner or later, you will get the moisture problem that is worrying you, but at least now you will know where it is coming from. Many flashing related chimney problems can be cured with a cricket, cant strip or all metal flash, proper tar work, and sawn-in counterflash . Here is a fairly clear picture of cricket and flash:

here it is with step and cap flashing:

here it is done in the absolute best detail:

[Tom The Great]

I would start ruling out other problems like ridge vent coming loose, bad shingle, etc.

tom @

[peter_nesbeitt]

Thanks for the links to flashing techniques. I had seen the one from copper.org before, but not the others. I tend to think the flashing was probably done correctly, because I had read up on these techniques and more or less enforced that it would be done that way, when the chimney was last reflashed.

As far as the suggestions from folks about hose-testing:

In theory... I am absolutely, totally in agreement with everyone who is basically saying "use the scientific method." By inclination and training, it's the right thing to do, and I'd do it myself if the house weren't so tall and the roof so steep.

In practice... In this neck of the woods (30 miles out from Boston), finding competent, available, insured folks in these trades (roofers, masons), with a lot of good experience, is a bit of a challenge. I've found some, but these folks are not in as high supply as perhaps they are in other areas of the country (or even state). One has in fact done a hose test, but perhaps not properly, and results were inconclusive. So... it's something which I've tried, and will look for more contractors to do it, and will also seek out infrared thermal imaging (someone suggested that, and it's a good idea)... but at the same time, am interested in thoughts on the relative merits of the options different masons/roofers have suggested.

In case it's useful... Here are 4 photos of the crown of the chimney (and flashing in one case):

Thanks, Peter

[Art]

One thing not done is to protect the top of the brick from water absorption with its own cap.

[peter_nesbeitt]

Sorry, I'm afraid I don't follow... the top of the brick? Could you explain a little more?

Peter

Art wrote:

[Berkshire Bill]

The chimney needs a bit of modification. You can see the water flowing down the side of the brick. Look here for a better description

Also you could benefit from a small metal cricket to shoot the water away from the house where your flashing ends. It's remotely possible the water is curling under at the end of the flahing and finding its way under the crown molding and siding.

Bill

[peter_nesbeitt]

Thanks for the article, Bill. That's a great one with all the diagrams, and I hadn't run across it yet. But I had seen somewhat similar diagrams (though not as detailed), which is part of what led me to think that the current crown (which looks to me like mortar rather than concrete) was perhaps not built quite right.

The water running down the side of the brick was actually because a chimneysweep had poured it there to see how quickly it was absorbed. I should have mentiioned that. Could be a little misleading otherwise.

Not quite following where the metal cricket would go, since this is a chimney at one end of the house...?

Thanks, Peter

[Moe]

wrote

Peter,

The flashing on the chimney is absolutely horrid! I definately question the ability of the persons responsible for such shoddy workmanship.

Besides the flashing being totally butchered, I don't see any front apron flashing which could be butchered.

Here's a couple of chimneys that I had done, unfortunately I don't have close up's of the work.

The one chimney which is 22' long, had approx. 15 people attempt to fix the problem b/4 I spent 2 days correcting flashing. After that, they had no further problems.

?action=view&current=R22ftduring.jpghttp://s132.photobucket.com/albums/q17/Roofguy/?action=view&current=R22ftfinal.jpg ?action=view&current=Rtallflashfinal.jpg

[Berkshire Bill]

I probably shouldn't have used cricket, as that would be above the chimney. I'm thinking of a L bracket or L panel to cant the water away from the house where your flashing ends.

Bill

[DanG]

Have a good tinner make a metal cap for the brick work. It could be made of copper if desired with the spark arrester designed into the piece. This would eliminate the problem being at the top. Here are a few examples:

~~~~~~~~~~~~~~~~~~~~ DanG A live Singing Valentine quartet, a sophisticated and elegant way to say I LOVE YOU! [e-mail] (local)

(national)

[peter_nesbeitt]

Thanks for posting the pictures, Moe. Your new flashing work is beautiful stuff (I can say that after having read a lot of web sites which show both 'bad' and 'good' flashing). Too bad you're not in the Boston area.

Yes, I'd say there's a good chance there's a flashing problem, although even though the lead has been bent back and forth a number of times and looks bad, I don't think lead develops pinhole breaks the way other metals do when they're bent back and forth a lot.

Peter

[hallerb]

SAFETY AL:ERT

THE CRACKED CAP, cement around liner is a real hazard, water gets in cracks freezes and breaks liner inside.

this nearly killed us from carbon monoxide poisioning........

whoever is doing your chimney work should know better!

[peter_nesbeitt]

Yep, the cracked mortar cap up there looked a bit dodgy to me as well. But, the cracks are hairline, so was never sure if much water could actually be penetrating that way and somehow working its way down the inside of the chimney and out under the flashing to make the attic wood wet... seems quite a journey for a drop of water.

Peter

[hallerb]

may or may not be the problem but the fact the chimney has been worked on so many times and cracks are still there tells me none of the workers knew what they were doing

CALL A CHIMNEY SWEEP, THEY SPECIALIZE IN CHIMNEYS and can at least refer the OP to someone reliable..........

again thoise cracks can kill, and even a little water can damage the chimney bad