Cement for stone chimney.

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GrumpyDad

Minister of Fire
Feb 23, 2022
1,232
Champion, PA
Sorry to create a new thread just for this.
What is a good cement (premix preferred) that a local box store would sell, that I could use on a stone rock chimney?

I have a leaking roof. It started in just one area, and during inspection it seems like it has been going for quite some time. Water runs down the chimney, then along the roof rafter, rotting a small board connected to the chimney, then it drips down through the tongue/groove ceiling then onto our refrigerator. Eventually I got up there with some sort of sealant akin to through the roof, and sealed around the flashing against the stone. This seemed to stop the issue. That was a few years ago.

Fast forward to a couple weeks ago, we had some hard rains. I was standing there talking to my wife about the stove I just put in successfully, when water dripped on my head. This is toward the end of the room, about 6' from the original leak. So I went up into the attic and saw water really coming in on both sides of the chimney. Running down the rafters and now hitting the edge of a very long and big cedar beam that we love the look of. After it stopped raining, I looked everywhere for possible penetration points. I sealed that flashing up really solid with my sealant years prior, and the sealant was in great condition surprisingly. Very soft and everything well covered.

The only thing I can think of is, I have some erosion in the mortar around the rocks that make up the chimney, some with green moss on it. I also have some rocks just chipping a layer off (must be sandstone).

My plan was to scrap/wire brush/chisel anything loose away, then fill with a good cement. After that, slather through the roof 1' around the chimney on the roof and up the stone chimney itself about a 1'.

Any other suggestions? I had a roofer that I know come out, aside from suggesting I go to a metal roof which I may do someday, he said 'welcome to what keeps me up at night'. He didnt really have any suggestions for what else I could try aside from what I'm planning above.
 
Sorry to create a new thread just for this.
What is a good cement (premix preferred) that a local box store would sell, that I could use on a stone rock chimney?

I have a leaking roof. It started in just one area, and during inspection it seems like it has been going for quite some time. Water runs down the chimney, then along the roof rafter, rotting a small board connected to the chimney, then it drips down through the tongue/groove ceiling then onto our refrigerator. Eventually I got up there with some sort of sealant akin to through the roof, and sealed around the flashing against the stone. This seemed to stop the issue. That was a few years ago.

Fast forward to a couple weeks ago, we had some hard rains. I was standing there talking to my wife about the stove I just put in successfully, when water dripped on my head. This is toward the end of the room, about 6' from the original leak. So I went up into the attic and saw water really coming in on both sides of the chimney. Running down the rafters and now hitting the edge of a very long and big cedar beam that we love the look of. After it stopped raining, I looked everywhere for possible penetration points. I sealed that flashing up really solid with my sealant years prior, and the sealant was in great condition surprisingly. Very soft and everything well covered.

The only thing I can think of is, I have some erosion in the mortar around the rocks that make up the chimney, some with green moss on it. I also have some rocks just chipping a layer off (must be sandstone).

My plan was to scrap/wire brush/chisel anything loose away, then fill with a good cement. After that, slather through the roof 1' around the chimney on the roof and up the stone chimney itself about a 1'.

Any other suggestions? I had a roofer that I know come out, aside from suggesting I go to a metal roof which I may do someday, he said 'welcome to what keeps me up at night'. He didnt really have any suggestions for what else I could try aside from what I'm planning above.
Post a picture of the chimney. And do not slather anything. It probably won't fix the issue and generally just makes it harder to fix it properly later.
 
Post a picture of the chimney. And do not slather anything. It probably won't fix the issue and generally just makes it harder to fix it properly later.
Thanks Bholler, it will be on Friday or Saturday likely. This is at our retirement villa (shack in the woods). I'll get close ups of the flashing, the rocks, the overall view of it. My / others caulking work so far.

Not sure if I mentioned this, but it only leaks when it rains fairly hard. It could rain all day consistently, enough to drench you if you were out there for a minute, and it wont leak. Im talking about the rain that when you run to your car for your phone, you come back pretty damn wet.
 
If you have sandstone, use type"n" mortar, it's the weakest
Well you just taught me something, I didnt know about the different types. I am usually fairly confused when I go to buy stuff that mixes and turns solid. I did 700 sq ft of porcelain tile in my basement and used mortar that was WAY more expensive than I probably should have used.
 
Well you just taught me something, I didnt know about the different types. I am usually fairly confused when I go to buy stuff that mixes and turns solid. I did 700 sq ft of porcelain tile in my basement and used mortar that was WAY more expensive than I probably should have used.
There are many different types of mortar that can then be altered by the sand and cement ratio. The main thing is you want your mortar softer than your masonry units
 
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I would also strongly recommend mixing your own mortar and adding acrylic modifier. The pre mixed stuff just doesn't work very nicely