So I'm installing a new fireplace and am in the process of reconstructing the chimney chase interior.
It is 28' high, it was only insulated to 8', and the first (and only) firestop for the previous unit was not insulated on top.
The manual for my new stove says to line the chase with Type X drywall. Ok, somewhat blindly I follow the instructions. Then I start thinking....
My question surrounds 2 things.
1) Moisture.
It seems to me, that not using the stove will create moisture problems. Because, when warm air becomes cold, it condenses. So, you have a cold flue, you build a fire, and now your flue becomes warm or hot. Now your chase becomes a moisture magnet because all of a sudden it was cold, and now it's warm. Tonight I observed just by being in the (empty) chase, I put 2 large lights in it (small amount of heat) and as I was insulating, I noticed a large amount of moisture on the underside of the chase top. Then it started to drip. Which led me to go take a look at the previous firestop drywall I had just removed, and yep, it was water stained, not much, but it was there. Then upon further inspection, I noticed a moisture ridden area of the OSB floor near an edge where nothing above it exhibited wet sign, like it was condensate.
So what really happens inside a chase when you start your stove up and it gets warm in there all of a sudden. I just insulated mine (R11) all the way, I tore the kraft facing off and stapled thru and used wire restraints. But before, it was uninsulated, except for the first 8'. What effect does a all of a sudden hot flue, or any hot flue, have on an insulated, and uninsulated, chase?
2) I just finished reading on Georgia Pacific's website that you are not to use Type X drywall in any situation constantly exposed to anything above 125 fahrenheit. Ok. But the manual of my new fireplace says "sheetrock your entire chase with type X drywall".
Nice, according to various things I've read and making a few calculation, my outer flue will be 60-120 degrees during normal operation. That's approaching the limits of type x drywall. I understand the nature of type x is to buy you time with the gypsum, but it's paper lined and seems to me it will create a more combustibles and more of a fire hazard in the room it's in. I think the point is to buy you time so the rest of your home doesn't burn down, but the low 125 constant temp concerns me, I think that chase will reach that temp in no time (especially if insulated, which it is now).
Please ease my mind with a days worth of hauling 5/8" type x sheetrock up a confined space in my chase as per the manual of my stoves instructions. Seems to me I just lined my chase with a bunch of combustible paper facing creating more of a fire hazard in that space.
It is 28' high, it was only insulated to 8', and the first (and only) firestop for the previous unit was not insulated on top.
The manual for my new stove says to line the chase with Type X drywall. Ok, somewhat blindly I follow the instructions. Then I start thinking....
My question surrounds 2 things.
1) Moisture.
It seems to me, that not using the stove will create moisture problems. Because, when warm air becomes cold, it condenses. So, you have a cold flue, you build a fire, and now your flue becomes warm or hot. Now your chase becomes a moisture magnet because all of a sudden it was cold, and now it's warm. Tonight I observed just by being in the (empty) chase, I put 2 large lights in it (small amount of heat) and as I was insulating, I noticed a large amount of moisture on the underside of the chase top. Then it started to drip. Which led me to go take a look at the previous firestop drywall I had just removed, and yep, it was water stained, not much, but it was there. Then upon further inspection, I noticed a moisture ridden area of the OSB floor near an edge where nothing above it exhibited wet sign, like it was condensate.
So what really happens inside a chase when you start your stove up and it gets warm in there all of a sudden. I just insulated mine (R11) all the way, I tore the kraft facing off and stapled thru and used wire restraints. But before, it was uninsulated, except for the first 8'. What effect does a all of a sudden hot flue, or any hot flue, have on an insulated, and uninsulated, chase?
2) I just finished reading on Georgia Pacific's website that you are not to use Type X drywall in any situation constantly exposed to anything above 125 fahrenheit. Ok. But the manual of my new fireplace says "sheetrock your entire chase with type X drywall".
Nice, according to various things I've read and making a few calculation, my outer flue will be 60-120 degrees during normal operation. That's approaching the limits of type x drywall. I understand the nature of type x is to buy you time with the gypsum, but it's paper lined and seems to me it will create a more combustibles and more of a fire hazard in the room it's in. I think the point is to buy you time so the rest of your home doesn't burn down, but the low 125 constant temp concerns me, I think that chase will reach that temp in no time (especially if insulated, which it is now).
Please ease my mind with a days worth of hauling 5/8" type x sheetrock up a confined space in my chase as per the manual of my stoves instructions. Seems to me I just lined my chase with a bunch of combustible paper facing creating more of a fire hazard in that space.
