How to seal around chimney flue

[RichC]

Hi, how do you go about sealing around the base of the chimney flue to prevent water from making its way in. I'm also a bit worried about maintaining render in this area as it's the one spot where there's a lot of heat. The rest of my dome is quite cool during a fire but the area around the flue gets hot.

Thanks

Richard

[brickie in oz]

Re: How to seal around chimney flue

Single or double flue?

[RichC]

Re: How to seal around chimney flue

Single flue

[boerwarrior]

Re: How to seal around chimney flue

Richard,

I was worried about the same thing and I am using several techniques!

First of all, I used my oven mortar blend (3:1:1:1) to fill in the approximately half-inch gap between the chimney and the roof (my roof is cement board). The chimney gets really hot so I wanted a heat resistant mortar in there. Then, I put fireproof sealant (that putty-like stuff) up against the chimney before coating the rest of the roof in stucco. Lastly (and I am sure this is unnecessary overkill), I used a 6-inch flashing collar installed over the chimney near the roof. Again, I used fireproof sealant to fill the small gaps between the collar and chimney. the combination of all of that seems to be working well!

[EliseR]

Re: How to seal around chimney flue

Hi Richard, we have a beehive finish (as opposed to birdhouse). We used refractory mortar around the chimney base, with a bead of chimney sealant. It's black stuff in a caulking tube. We got ours at Menard's in MN (a big box store like a Lowes or Home Depot). No leakage issues in 2 years. Good luck!

[cobblerdave]

Re: How to seal around chimney flue

Richard,

I was worried about the same thing and I am using several techniques!

First of all, I used my oven mortar blend (3:1:1:1) to fill in the approximately half-inch gap between the chimney and the roof (my roof is cement board). The chimney gets really hot so I wanted a heat resistant mortar in there. Then, I put fireproof sealant (that putty-like stuff) up against the chimney before coating the rest of the roof in stucco. Lastly (and I am sure this is unnecessary overkill), I used a 6-inch flashing collar installed over the chimney near the roof. Again, I used fireproof sealant to fill the small gaps between the collar and chimney. the combination of all of that seems to be working well!

Gudday
You might consider just using the flashing collar by itself and leave the outside of the chimney to act like a natural vent for the oven should it get damp. You can seal on oven against the elements but if its to well done it makes it hard to again release that moisture. The brickwork in the interior of your oven will absorb water from the air.
Regards dave

[RichC]

Re: How to seal around chimney flue

Thanks guys! Decisions, decisions ....... Still need to cast countertop and render dome so it'll be the new year when I have to make my kind up

[boerwarrior]

Re: How to seal around chimney flue

Gudday
You might consider just using the flashing collar by itself and leave the outside of the chimney to act like a natural vent for the oven should it get damp. You can seal on oven against the elements but if its to well done it makes it hard to again release that moisture. The brickwork in the interior of your oven will absorb water from the air.
Regards dave

Dave, I totally agree that you also need vents! I have two 4 inch circular aluminum vents on the side walls of my surround structure. I used the ones with the little louvre's that face down so that they also protect from sideways driving rain.

[rosewood]

Re: How to seal around chimney flue

I live in Ohio where the air can get quite moist and think I have this issue happening with my oven. How do you deal with moisture once it gets in the oven and inetrior brick? Would you consider this a major issue that will cause problems over time? If so, what are my options?


Joe