In 1990 I had a post and beam home with a stress skin exterior and roof built for me in central Maine. Since the roof had an R-value of 43, I was advised to have a “cold roof” installed over the roof panels, which I did. I had two granite fireplaces with fairly massive random size granite stone chimneys. One of the chimneys is in the center of the house and the other was on an exterior wall.
My problem is: the chimneys leak on the exterior surface inside the house, big time. Especially the interior one and mostly when there is a wind driven rain. The interior one also leaks when snow build up on the roof starts to thaw.
So far my contractor and I have had limited success. The wind driven rain problem goes away for a while with each thing we try and returns a year or so later.
After checking the lead flashing and finding it very well done by the master stone mason who constructed the fireplaces,since retired from the business, we ruled out faulty flashing,
We detected numerous hairline cracks in the mortar and took action to try and come up with a fix for these cracks. I tried to plug the them with a flexible caulk. The problem went away for about a year and returned with a vengeance. The caulk was separating from the mortar due to the sand in the mortar breaking loose from the surface of the mortar causing the caulk to separate from the joints. Another stone mason suggested tuckpointing the entire exterior surfaces of the chimneys. It would have been expensive and I felt I would have the same leakage problem a few years down the road with more cracks so I applied an industrial strength clear sealer. This try only lasted a year.
My contractor went on a search for that “miracle” product that we knew was out there and he came up with a thick plantable rubberlike substance (they took the empty cans with them when they left so I don’t know exactly what it was. It was clear, but had a high gloss that didn’t appeal to me up close with the sun shining on it. From a distance it was not all that noticeable. It worked great!,for about three years. The record rains we experience last month had the water almost to my mantel from my 20 foot cathedral ceiling.
I am seriously considering applying stucco to the entire exterior parts of the rock face! My contractor darkly hinted at bodily harm if I covered my beautiful but troublesome chimneys.
The melting snow problem may be solved by a cricket.I’m going to try that and if that fails go to a heat strip around where the roof meets the stone as it penetrates the roof.
We are open to any suggestions to help us with this very vexing problem.
Replies
Stucco will still leak.
You need through flashings, but that entails taking the tops down to just above roofline and rebuilding them up on the sheet of lead running through the whole to kick the water back out.
Sorry for the bad news, but masonry is not watertight.
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"My problem is: the chimneys leak on the exterior surface inside the house, big time. Especially the interior one and mostly when there is a wind driven rain. The interior one also leaks when snow build up on the roof starts to thaw.
So far my contractor and I have had limited success."
DDW,
My Dad's house had a similar problem years ago. My fix, which has lasted 15 years so far, was to flash the entire chimney with a single sheet of galvanized steel. then put an overlapping cap over it, and paint it to look like brick. It looks just like brick from street level.
WSJ