In my area of New Jersey there are many one hundred year old houses with true stone chimneys, not veneers of stone on block. When it comes to re-roofing a home like this, what is the proper way to flash the chimney? It is not possible to cut in a groove for counterflashing. Some roofers add cement to the bottom 12 inches or so of the portion of the chimney above the roof to create a rectangular “box” which they can flash to. Others wrap flashing up the chimeny and fill the cavity between the flashing and the irregular stone with silicone sealant. The silicone has a shorter life than the roof. Others flash up the chimeny and cover the top of the flashing with lots of roofing tar. Any comments?
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Why should it not be posible to cut the stone for flashing / counterflashing?
I've always assumed that it would be impossible to cut in for counter flashing. The mortar normally is a squeeze joint, that is, the joint is convex. Also the stones are not dressed, but are fieldstone boulders. Wouldn't counter flashing need to be cut in between stones and therefore make an odd sort of swooping shape vertically?
Edited 2/3/2009 6:05 pm ET by JPNArchitect
It should be flashed in two parts - base flashings in with the roofing materials and then counterflashed from the stone down over the base flashings.
The reglets cut into the mortar joints will follow the natural profiles of the stones so the lines may not be as perfect as with bricks.
The methods you've outlined are suspect at best.
I'd do like walter and use a copper base flashing, then use lead formed to fit each step and a grinder to let it in at each mortar joint. The lead can be fitted to the stone easily enough and I prefer geocel to silicone., but that lead has to be leet into the masonry.
The guys using tar gobs are shingle layers, not roofers
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Best is to tear the chimney down to the roof and do thru-flashing, then rebuild the chimney.
;-)
Just cause you've got a leaker -- don't go making more work for the rest of us !!! <G>
LOL
I like to spread the misery around!
There's already plenty to go around !!!
walter, piffen , mike are all talking about the same thing......
base flash... thru-flash
it is impossible to flash a stone chimney with any guarantee of success unless you do it that way
the usual method is that at some point ( usually just below the roof line )
you layup a masonry base of block or brick , stepped up the roof, then you bring your flashings ( lead, lead-coat copper, copper ) OVER & THRU the base and typically up the side of the flue (s)
then the mason continues laying up the stone chimney as required
the stone "sits" on the "base-flash" ( thru-flash )
the flashing theory is that any waster that gets thru the stone or thru the cap will run down, hit the thru-flash , and then follow weep holes outMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Mike,
I think he's talking about an existing stone chimney - not one being built now.
Your description would be perfect for new work , but I bet they're not willing to do a tear down and re build it.
Talent pool doesn't sound like they could complete the process you described either -- judging from his roofers 3 suggestions.
Walter
walter.... know the phrase ?
"you touch it, you own it " ????
i'm with Mike Maines.... i take the roofing job.... we're tearing the chimney down and installing a new thru flash and redoing the flues while we're at it
if it's an inside chimney.... might be a good time to tear it down to the attic floorMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Yup I know the phrase real well. I own a lot of flashing work in Eastern Maine !!!
I was half-joking...but at my family's camp, and on several jobs, we've had persistant "leaking" problems with natural stone. The ones we've done with through-flashing have worked out much better.
ok..... here's a roofing job...
roof / chimney been leaking.....
needs a new roof, no matter what
field stone chimney, 100 years old
whatter your specs gonna say ?Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Mike - I've solved the no thru flashing problem numerous times with a full chimney cover. 9 out of 10 times, the water is getting in at the top of the chimney.http://www.quittintime.com/ View Image
good point...
i think your stone is usually more squared off than ours... Here a typical stone chimney will be field stone.... and theyre's no telling how many voids that can concealMike Hussein Smith Rhode Island : Design / Build / Repair / Restore
We've got a lot of fieldstone here as well.
I typically make the cap 2"-3" larger than the top of the chimney so it takes a pretty hard blowing rain to get any water past the 2" deep counter flashing. http://www.quittintime.com/ View Image
what am i ....... dense ?
jpn..... you should spec one of Grant's chimney caps
just click on his logo and have a look !Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Knowing some of our clients probably something like "honed granite counters and subzero fridges, outdoor work to be completed in phase 2 (deferred)."
While I understand the concept being proposed; that one way to flash and counter flash this chimney may be addressed by taking the chimney down to the roof and rebuilding it - this can not be the only way to provide flashing at an existing chimney. In one project I'm working on, not only is there one stone chimney which penetrates the roof and needs to be reflashed when the roof is redone, but this same chimney has another roof abutting it on a lower level. I don't think I can tell my client that the only way to reroof his home is to take the chimney down from above the third floor to just above the first floor. We'd end up not only replacing the roof but half the chimney and its flues as well as significant stucco patching where the stucco meets the chimney.
The idea of providing a new reglet and inserting counter flashing in it makes sense to me; it would just look odd as the fieldstone is large and uneven.
There are no leaks now at this house.
I appreciate the comments.
Edited 2/3/2009 6:02 pm ET by JPNArchitect
You've got to find a good sheet metal mechanic to flash those chimneys properly.
The ways you mentioned earlier had no merit and shouldn't be considered.
It can be done without rebuilding the chimney - maybe not quite as leakproof for another 50 years , but like Seeyou suggested cover the top with a metal top.
jpn.....
first...... welcome to Breaktime
second:
a picture is worth.....
got any pics of the existing conditions ?
Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Edited 2/3/2009 6:36 pm ET by MikeSmith
I'll post photos tomorrow.
Photo attached of a typical condition. This is a photo of a roof over a first floor, where it meets a chimney. The chimney continues from this point past the second floor where is picks up another fireplace and flue, then up to the roof bove the third floor.
This particular roof was reroofed 15 years ago and there is no leaking around the chimney. I just don't think the silicone caulk, which is the primary seal, is the proper way to deal with this.
There are three flues in this chimney by the time it exits the roof and there is no brick or block, just stone and terra cotta flues.
There is a metal chimney cap.
Thanks for the help.
Photo attached of a typical condition. This town has many homes like this, so as an architect I am runnng up against the way to properly flash against a stone chimney all the time.
This is a picture of where a chimney meets a roof over a first floor room. The chimney continues up past the second floor where another flue is added and then up to to exit the roof over the third floor. There are three flues in the chimney.
This particular roof was reroofed fifteen years ago and there is no evidence of leaking. There is a metal chimney cap.
The silicone bead just seems wrong to me. Running a reglet seems like a good idea. Is there any problem with cutting a reglet in one hundred year old mortar?
Thanks
you should resize your pics so all can see them..
View Image
do you have any other views that show the whole chimney ?
like the cap detail ?
Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
Edited 2/5/2009 11:13 am ET by MikeSmith
In spitew of the photo file size, I can't see thedtails there very well. It almost looks to me like that black metal has been turned into the masonry like CU was desribing. With a metal cap on top, that does work most often
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We've cut many of those in with a diamond wheel in a 4.5" grinder, nothing to it.
I personally like lead, but when I worked with SeeYou , we mostly used copper. Either way, you need a better roofer that has true flashing exp. and not a shingler that hasn't.
There will still be caulk , like Geocel or Lexel ( no silicone) used, but only to seal the kerf after the install.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
They kill Prophets, for Profits.
while you're at it do something about that sidewall flashing.
How deep do you need to cut into the stone?
you do see the propensity for fissures in the stone to allow water to the interior of the chimney , right ?
View Image
once it's inside , it has a mind of it's own and a let-in reglet is not going to do much...
it's a good detail to redirect the surface water
but the cap water needs a cap detail..... and any other water needs a thru-flash
you should have your clients be aware that there are no guarantees with a chimney like that
Mike Hussein Smith Rhode Island : Design / Build / Repair / Restore
That little cricket detail looks like it would benefit of being all exposed metal pan too.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
They kill Prophets, for Profits.
YAH< THAT WAS JUST AN EXCUSE TO POKE NAILS INTO THE FLASHING
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Nails? They probably just gooped em down with Black jack.
I could see a nice copper transition there. So the main roof don't direct run off up under the counterflashing.
Why are ya yelling at me? I'm right here (G)Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
They kill Prophets, for Profits.
oops
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
It varies with the jagged ness of the stone, but a 1/2" is a good minimum to shoot for.Spheramid Enterprises Architectural Woodworks
Repairs, Remodeling, Restorations
They kill Prophets, for Profits.
You mean the chimney hasn't leaked yet-- ;-)
The problem with natural stone, at least what I've seen in New England, is that tiny cracks appear between the stone and the mortar. Maybe due to differential movement, I don't know. Water finds its way into those cracks and down through the stonework. Flashing and counterflashing is great but it doesn't protect against water finding its way down through the stonework. But through flashing is rare; obviously most people get by just fine without them.
It just isn't much fun when at the end of a big renovation, the chimney your company never touched, except to install a new cedar roof, leaks all over the brand new oiled birch floors and ruins the paint job on the spray-painted cathedral wood ceiling. Not that it's happened to me in the last year or anything....
The other method we sometimes use is to grind a reglet parallel to the roof right thru stone and mortar. We use a 7" grinder and let it ride on a 2x4 laying on the roof. The flange that fits in the reglet is usually bent at about 2 1/2" to 3" and then scribed so the flashing fits as tightly as possible to the irregular face.
http://www.quittintime.com/ View Image
Here's a pic of a true stone chimney flashed in the mortar joints. I'm looking for a straight reglet pic.
http://www.grantlogan.net/Grand_Manor_shingles_-_stone_chimney_flashing.jpg
http://www.quittintime.com/ View Image