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missing flashing/sealing around chimney?


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I own a 1937 cottage house in North TX, and it has a chimney on one gable end. After a recent week of rain, I noticed some drip marks on interior drywall around one edge of the chimney. There is no chimney cap or damper.

When looking at the chimney from the attic, I see the following gaps on both sides of the chimney:

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Should there be flashing outside to seal these gaps?

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Yes, there should be flashing there now -- and there was originally. Unfortunately, in the 70-odd intervening years, several roofers have been up there replacing the shingles. The original flashing likely rusted out (if it was galvanized) or was damaged during one of the reroofs if it was copper. Usually, the roofers remove the old flashing and goop the area up with tar. That's faster and it lasts long enough for them to get paid -- and out of warranty on workmanship.

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You didn't say that you are missing flashings at the intersection of the roof and chimneystack so I guess you're only concerned with these gaps.

Gaps on the sides of chimneys like that are pretty common. Here in the northwest we have deep overhanging eaves on most homes and they are almost never an issue. However, I can see where they'd be an issue in an area where the homes had shorter eaves or no eaves at all.

Around here, when there aren't any overhanging eaves or it's a pretty tall house where the eaves don't provide much protection builders will install a piece of trim in those corners and butt the siding right up to the trim and use something like butyl (synthetic rubber) caulk between the trim and the chimneystack to form a permanent flexible seal.

What kind of siding do you have?

ONE TEAM - ONE FIGHT!!!

Mike

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You didn't say that you are missing flashings at the intersection of the roof and chimneystack so I guess you're only concerned with these gaps.

Correct, I can see flashing at the roof intersections, so the top appears to be fine. The pitch is so steep that I'm not comfortable going up there to check, but Nolan gave me a local roofer recommendation to call for that.

Around here, when there aren't any overhanging eaves or it's a pretty tall house where the eaves don't provide much protection builders will install a piece of trim in those corners and butt the siding right up to the trim and use something like butyl (synthetic rubber) caulk between the trim and the chimneystack to form a permanent flexible seal.

Awesome, that's exactly what I was wondering.

What kind of siding do you have?

The original wood drop siding is covered with Al siding from the 50's. Eventually the Al siding will come off and the wood will be restored & repainted.

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The original wood drop siding is covered with Al siding from the 50's. Eventually the Al siding will come off and the wood will be restored & repainted.

Yeach!

That makes it a little tricky. A straight edge, a circular saw with a carbide blade set to just reach the back of the aluminum (or a smidgen less so you can finish the rest of the cut with a utility knife) and you should be able to cut away enough to make room for a piece of trim plus the thickness of the J-channel (which you'll need to salvage).

I'd probably try a strip of 3" wide moistop self-adhering bituthene flashing in that corner behind the trim and fill any gaps caused by the irregular brick surface between the surface of the bituthene and the trim with some butyl.

Come to think of it, Big Stretch would probably work better - it's a flexible/stretchable caulk that's water-based and easier to clean up than butyl.

ONE TEAM - ONE FIGHT!!!

Mike

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How soon is eventually? If the aluminum is going to come off in a year or two just caulk the J channel to the chimney with clear silicone, anything else will be a pup to remove. If refinishing the original siding is going to be more like a five or ten year plan then follow Mike's advice, but I'd cut through all the siding and flash to the sheathing. If you're gonna do the work, you might as well go all the way.

Tom

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