Moisture problems

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Damien69

New Member
Aug 29, 2024
10
Ontario
Hey Guys, if this is in the wrong section forgive me. We have a 70s sealed up fireplace and noticed we're getting moisture, mold and efflorescence around the hearth inside. Started with the main culprits.. cap, crown and flashing all OK. Pulled off the wood where an electric fireplace was installed and found a ton of insulation leading to the old Firebox soaked. Attaching some pictures, any advice on how to move forward would be greatly appreciated.

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Video inside looking up the flue.
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Are the butt ends of the gutters sealed properly? (Or do they shed water into the chimney bricks?)

I would remove the cap and cap off the flue. You can do that with metal, tapcons, and silicone to seal.

I do think water is slowly entering the flue, and the insulation doesn't dry out, leading up to a slow seeping. Best to just close the hole up top if you don't use it anymore.
 
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Are the butt ends of the gutters sealed properly? (Or do they shed water into the chimney bricks?)

I would remove the cap and cap off the flue. You can do that with metal, tapcons, and silicone to seal.

I do think water is slowly entering the flue, and the insulation doesn't dry out, leading up to a slow seeping. Best to just close the hole up top if you don't use it anymore.
Sounds like a great idea, seal the flue and I'll monitor over the next few rain falls. Honestly seeing inside to the old Fireplace makes me want to open it up and make it usable.
 
If you go in the direction of using the fireplace, this site is a wealth of information for helping you determine if it may be safe to do so. Definitely wouldn’t assume it would be good to go.
 
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You can just tape a garbage bag over it for a temporary cover.
Rain can definitely be blowing past that cap and down the flue. It happens to me during heavy wind driven rain.
 
You can just tape a garbage bag over it for a temporary cover.
Rain can definitely be blowing past that cap and down the flue. It happens to me during heavy wind driven rain.
I noticed I have mold on the far corner too where the stud/drywall touches the brick. Would the water wick over that far?

[Hearth.com] Moisture problems
 
Check the drainage from your window sills.... Do they leak into the wall?

On the other hand, that should never get into the flue... So that (cap) advice still stands imo.
 
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Also check those gutter ends as Stoveliker mentioned in his other post. That would be the main culprit. Even if it does have a good seal on the end caps by the chimney (which i bet it does not), They can still overflow if the gutter has any debris in it or a huge storm overwhelms the gutters.
 
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That new flashing on the chimney and the way they did it suggests there has been a water problem in the past.
 
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It looks like there's solid foundation on the inside, I was thinking this was a fireplace but this had to be a wood stove right?

[Hearth.com] Moisture problems
 
I am not sure what I'm looking at, but the chimney will need a foundation too - it's a lot of weight...
So I don't think you can conclude anything about stove or insert here, and I don't think it matters?
 
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Looks like ground water is getting in below the flue, looks like I'm digging this weekend.
 
Wow, yes, if it's not raining when you took the video, it's ground water. A lot...
 
Yep. No water from above means thru the ground. Digging but no detective on the roof...
 
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Good sleuthing. That's not good. Is the fireplace on the first floor or below grade in a basement?
 
Good sleuthing. That's not good. Is the fireplace on the first floor or below grade in a basement?
Thank you! Finding some answers feels better. It's below grade, looks like I have to dig up about 6-7ft to find that spot the drip is coming from. I'm hoping we can keep the brick hearth after it's dried out when the waterproofing is dealt with.
 
Check the drainage from your window sills.... Do they leak into the wall?

On the other hand, that should never get into the flue... So that (cap) advice still stands imo.
I would have to disagree. Moisture is gonna need a way out. Sealing that cap won’t allow it and may make the problem worse. Especially if that’s not how it’s getting in. I don’t think k blowing rain will cause that much water issue
 
It is best to fix all moisture ingress from the exterior. Where else could it be getting in that you can’t see?
 
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He found it. Underground. Going to dig.
 
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He found it. Underground. Going to dig.
The question is where to stop digging? Footer to confirm you have a perimeter drain? I’ve been through this. We put basement windows right where I knew I had a leak. You could hear water running down inside the cinder blocks.

We were digging big hole so we went down to footer to find there was no drain. So we added one to daylight. Not cheap but it was the right way. And I added gutters.
 
Yes, I'd dig all the way down, but I think that that leak observed in the video is close to being all the way down.
 
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Hey guys little update, I've dug close to 5 foot below grade. Had to get the hose out the clear the dirt to observe mortar joints, corners look pretty questionable.

[Hearth.com] Moisture problems
 
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