Water Leaking Around Chimney Box (with pics)

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PatrickWR

New Member
Apr 14, 2021
8
Oregon
Hi folks. I've read a few threads on this topic and wanted to get some advice on my situation. I had a new chimney installed last year (March 2020). No previous chimney had existed in my house. The spot we picked required quite a bit of Class A pipe to achieve proper height, which you'll see in the pics. It's a straight chimney, no bends or curves.

I've noticed during heavy rains or windy rains that the attic support box will leak water. Not a lot, but enough that it's a nuisance. I hate water intrusion into my home (battle scars from past basement flooding). The water splatters onto my stove and I'm worried about eventual rust. The drips appear to be gathering in the lower lip of the support box, where the stove pipe enters the ceiling. This suggests to me that the water is coming down the inside of the chimney in some manner.

I explored the installation this week and took some photos of what I saw. The storm collar appears to be installed and caulked heavily (they did a second round of caulk at my request, so it looks pretty gnarly). The gap between the chimney and the flashing cone appears to be well covered by the storm collar...I just don't see how wind-driven rain getting up under the storm collar could be causing this issue. Here are some pics.

PXL_20210929_174711910.jpg PXL_20210929_175051329.jpg PXL_20210929_174938905.jpg PXL_20210929_174848393.jpg

My questions for you:
  • Should I caulk the vertical seam on these Class A pipe sections?
  • Should I caulk the horizontal joints where the Class A sections are fitted together? In one of the pics you can see what appear to be fingernail sized gaps, or maybe they're crimps, where the pipes are fitted together.
  • Could the chimney cap be the culprit? I have considered replacing it with one of those slanted wind directional caps. It's waaay up there and I'd probably need to engage a pro to swap it out.

Thanks for your assistance.
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,694
South Puget Sound, WA
I would try caulking the vertical seam of at least the first length. Nothing worked for our old Selkirk chimney installation until I did that.
 
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EatenByLimestone

Minister of Fire
I had wind issues blowing water up under the storm collar. At least I'm pretty sure that is what was happening. I put a quality aluminum tape over the seams and never had an issue again.
 

stoveliker

Minister of Fire
Nov 17, 2019
2,049
Long Island NY
I have exactly the same issue. Outside situation and water appearance inside in exactly the same spot. (This is the chimney for my oil boiler.)

I had seen the result of old water intrusion (oxidation) inside, but never seen water. Until I looked in the boiler room after a very windy, very rainy storm. "Horizontal rain". Puddle on the floor.

Went up, caulked the seams. One more storm and I saw a drop hanging. (And the roof is less than a year old, done professionally.

I'll be caulking the vertical seam too.

I did see that under the storm collar there were 2" vertical slits in the pipe. I presume those are to vent heat from the outside of the insulated pipe
I was wondering whether water can spatter up into those slits. (But I'll be caulking the vertical seam nonetheless.)
 
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kennyp2339

Minister of Fire
Feb 16, 2014
6,129
07462
Best to first go into the attic if its that type on structure and see if you can find any water marks on the outside skin of the class a pipe.
 

stoveliker

Minister of Fire
Nov 17, 2019
2,049
Long Island NY
Can't see it there; roof slope too shallow and the pipe runs up close to the wall. Can't stick my head between roof plywood sheet (nails...) above and ceiling joists below far enough to have a look. Tried with cameras but no luck .
 

PatrickWR

New Member
Apr 14, 2021
8
Oregon
Thanks for the insights, I'll be going up to caulk the vertical seams and the joints between each 4 foot section as soon as things dry out around here.
 

PatrickWR

New Member
Apr 14, 2021
8
Oregon
Just wanted to circle back on this and report on what I did.

I got some high-temp silicone caulk and climbed up on the roof and caulked every connection point I could see - vertical seams and horizontal joints between pipe sections. I wasn't able to get all the way up to the tip top, but I probably did 50% of the exposed pipe. (Remember, this is a tall chimney)

Anyway, that seemed to make a difference, and I have not had water intrusion since then (despite getting slammed with some Pacific cyclone remnants a couple of weeks ago here in the PNW). So, I'm cautiously optimistic that I have solved the problem. I will be reporting this back to my installer so they have a data point if more customers call about this.
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,694
South Puget Sound, WA
Good deal. I think you have the problem solved.
 

stoveliker

Minister of Fire
Nov 17, 2019
2,049
Long Island NY
Same here; did the vertical seam (only one that had not been done yet), and the two storms we had here produced a lot of rain outside and none inside.
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,694
South Puget Sound, WA
I tried several other fixes with our old Selkirk chimney. Nothing worked until I siliconed the vertical seam.