Water entry at bottom of vinyl-sided chimneys that jut out

I’ve recently done a couple of inspections in which there was water entry into the bottom of chimneys that were vinyl-sided and configured as in the pics shown here. The water appears to run down the bottom panel (which was rotting in both cases), and into the basement. This appears to be a systemic design flaw.

My thought is that the water works its way around the edges of the siding in the corners and is caught and drawn in by the “J” channel border that was idiotically installed on the bottom of the course of the siding. With 2 stories of runoff, it certainly appears easy to see how water got in.

My question is how does one fix this with a minimum of surgery?

It seems to me a different configuration that replaces the “J” channels on the bottom and sides would make more sense, but that would involve re-siding the entire chimney, all 2-3 stories of it. It seems that re-configuring the bottom of the siding so water is run out, rather than in would solve most of the problem.


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Ridgeside 2.gif

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I have my own report and appendix which took a couple of months to generate. In the appendix, the largest section is about moisture which I start off with this sentence:
“Water is the largest destroyer of value in Canadian buildings”

There are at least 3 wrongs in the pictures shown.
(1) No caulking between the vertical J and the wood cornerboard
(2) Simply a horizontal drip cap/ Z flashing installed over the horizontal bottom trim board. What keeps the water from getting behind the wood at the corners where vertical and horizontal pieces meet?
(3) The middle picture shows a butt joint with caulking. The caulking will dry/shrink leaving a hairline crack which draws water in by capilliary action. This type of joint does not shed water
like shingles & clapboard or a ducks feathers.

A possible #4 is that they probably did not “back prime” or paint all sides of the wood. This unpainted wood becomes a resevoir for water that bypasses the first line of defense. It does not dry out as quickly as it did in the past since our houses are more airtight and don’t bleed heat out the walls which usually used to dry this type of moisture intrusion.

I don’t see any Z flashing on the bottom trim, did they use any kind of house wrap?

Another problem is that there is no drip provided at the bottom of the chimney, so water will run down the face of the chimney and then some will fail to drip from the bottom, collect there, and find its way into the house.

The siding should extend all the way to the bottom, not stop flush on top of the trim, and it also needs a drip edge. Poor installation, but it should be fairly easy to correct without having to replace all of the siding on the chimney.

What did they do at the top/cap of the chimney!

Did they run the siding over the old cap?

Good call.
Get rid of the trim at the bottom and extend the siding to the bottom.
Rather than useing “J” ,a “starter strip” would be a way better component in this application .
As already mentioned, the chimney cap should bend over the siding.
This is not a difficult or expensive fix.

The tops of the chimneys had metal caps that looked fiine, so the leakage appeared to be strictly siding-related, along the vertical J channels and in the bottom J channel. I saw no evidence of any sort of drip cap/Z flashing on the bottom of the siding.

That should solve the problem, Ken.

Also, a configuration that involves 2 Z flashings with a properly overlapped flat metal flashing on a separate board between them, if properly installed, should direct any water out and solve the problem, while maintaining a more consistent appearance.

Even though the siding should be caulked along the vertical “J” channels, it stands to reason that any water that gets in there would mostly be drawn in by capillary action, and would still run down the chimney.

Thanks for your responses, everyone.

Did the top of the chimney have a wood trim band around it that the flashing was out and over?

If so the siding stopped below it just like the rest of the trim and with out flashing at that pointe it is now a funnel.

Good call.
Get rid of the trim at the bottom and extend the siding to the bottom.
Rather than useing “J” ,a “starter strip” would be a way better component in this application .

quote]Exactly. Pop the bottom row off, install aluminum flashing, eliminate the “J” channel and use a starter strip. There will be nothing to catch the water and it will run off. Flashing just for precaution, wind , ice, etc.