Capping an unused Chimney on a flat roof
- Thread starter branimal
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Buckaroo5
Well-known member
I would put a heavy bead of caulk on the brick perimeter around each opening and lay a long piece of sheet aluminum across it.
58Yeoman
Well-known member
What Buckaroo5 said. I was lucky. I have two chimneys, but they're the insulated SS pipe. One is for a fireplace in the living room that we never use, and the center hubcap from a 14" smoothie wheel fit right onto it.
mitusa
Well-known member
How about using your break and building a lid that came down a couple of inches on each side. Might also add a piece of styrofoam insulation in the lid and use the caulk as noted above.
Not sure where you live, but when I did something similar, I made a cover with a brake that had a foldover edge of a couple inches so that I could attach it with some screws and some good quality sealant.
I've found some folk's chimney cover that launched in a strong wind and the when I found it there was nothing, and they were relying upon gravity to hold it in place.
I've found some folk's chimney cover that launched in a strong wind and the when I found it there was nothing, and they were relying upon gravity to hold it in place.
AC-WC
Well-known member
Silly question-is there any way anyone could use the fireplace (or what ever) and accidentally attempt to use the chimney?
They're out there is all I'm saying...
They're out there is all I'm saying...
rlitman
Well-known member
I had an unused chimney in my house. I brought in a roofer to demolish it into the attic and frame the roof closed over the hole. Eventually I got a contractor to take it down to the slab and reclaimed the interior space (it was not structural in any way). That roof penetration (even with a proper curb) is just a liability.
rlitman
Well-known member
You could, but I wouldn't. It was the first thought that came to my mind on seeing this thread though. A 24" ceramic patio tile might cover the whole thing. But even with some overhang, you need a drip edge on the overhang to ensure water doesn't run down the outside of the brick and get behind the roof curb. Yeah, there are ways to cut a drip edge into stone (much as you would under a wooden window sill), but it's just much easier to get this to work in aluminum.
yup, bend up some aluminum or galvanized stock , some tapcons around the edges to secure it and call it done.
nadogail
Well-known member
Cap it with an appropriate sized can or bucket. You might want to use it at some later date
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OccupantRJ
Well-known member
An old school brick layer told me, joking or not, that a technique was secretly to lay a sheet of glass in a mortar joint near the top of the chimney and tell the suspect-pay customer that the chimney would need special activation after the bill was paid, and not to try to use it until then. If the customer paid, the glass would be broken out. Even if an urban legend, that would do the trick.
OccupantRJ
Well-known member
We do not use our fireplace and had issues with starlings creeping out my wife chirping in it, so I made a galvanized sheet metal pan and bonded it to the chimney as a cover. With the damper closed it has a comforting faint pitter patter when it rains. A sheet of foam insulation under it would silence that, but I like that I can tell when it first starts to rain from my chair In case I left something outside.
Pretty good video on building a chimney cap with a brake. (Link below). I don't have a roller bender, so i'll bend. the long side on the brake and the short side by hand.
Chimney measures 12" x 36 1/4". I'll add 1/4" to each side to give myself some wiggle. 2 1/2" overhang. 1/2" hem.
In the video he does a cool X profile on the top to give the cap some pitch. I'm guessing that will shrink the internal dimension of the box. Maybe I mess around with it add another 1/4" to each dimension.
@rlitman Drip edge - good idea. I've done them on the brake before. Not sure how I'd do it along with the box profile.... It gets confusing. And it might be overkill.
Chimney cap on aluminum brake
Chimney measures 12" x 36 1/4". I'll add 1/4" to each side to give myself some wiggle. 2 1/2" overhang. 1/2" hem.
In the video he does a cool X profile on the top to give the cap some pitch. I'm guessing that will shrink the internal dimension of the box. Maybe I mess around with it add another 1/4" to each dimension.
@rlitman Drip edge - good idea. I've done them on the brake before. Not sure how I'd do it along with the box profile.... It gets confusing. And it might be overkill.
Chimney cap on aluminum brake
gahrajmahal
Well-known member
We have stainless steel caps on ours (working chimneys). They are a little over size, maybe 1/4” all around. I filled the gap with rigid siding then caulked because insects were building nests in the gaps.
Boostingaz
Well-known member
Just finished mine today. This is what I did.
I built a cap for an unused doghouse. (ventilation stack for a old brooklyn rowhouse). I built it a little bigger so I wouldn't have fitment issues. Over did it a bit too much.
Can I bend a u-channel and glue/ rivet it onto my cap to take up the space? Or is there better way?
I'm planning on securing the cap with construction adhesive. All the cap seams will be sealed with rubberized roof caulk. Maybe I'll use some screws as well.
Can I bend a u-channel and glue/ rivet it onto my cap to take up the space? Or is there better way?
I'm planning on securing the cap with construction adhesive. All the cap seams will be sealed with rubberized roof caulk. Maybe I'll use some screws as well.
Attachments
make sure you securely mechanically fasten the cap to the brick. heavy winds can make that a large sail when it gets underneath & starts ripping it off
Roger that. That cap took a lot of mental energy to make. I'd be devastated if it flew away.
I had an old stone chimney that had a SS liner and a woodstove connected that was the primary heat.. The chimney was smack in the middle of the place. I tore it down to the foundation and it allowed a completely open floor plan. Your plan to simply cap is the simplest, but sit for a minute and imagine how the space would be if the whole thing was gone.
Nice work on the cap, as others have mentioned use mechanical fasteners. Always try to go through the side vs top, less prone to leaking. Caulk the hole and rivet/screw as well. Fill void (see below)
For filling the void between oversized cap you might get away with backer rod, a medium density foam cord that is designed for this. Depends on your void size?
If you need to use aluminum, I would taper the shape you have. Makes fitting odd gaps easier, leave the legs facing down.
For filling the void between oversized cap you might get away with backer rod, a medium density foam cord that is designed for this. Depends on your void size?
If you need to use aluminum, I would taper the shape you have. Makes fitting odd gaps easier, leave the legs facing down.
I believe he lives in NYC, not a regular neighborhood but townhouse/brownstone. Fireplace probably needs inspected, rebuilt/lined. I can only imagine the neighbors with reporting smells of smoke in the area like that not to mention the availability of trying to get/store firewood. Insurance issue ?
All valid and interesting points. Such a foreign thing to me to have to think about things like surrounding such a common everyday item like a fireplace.
MrPink
Well-known member
I have to do this but my chimney was terminated back into my attic space when they put the new roof on in `23. so i am going to caulk a piece of aluminum on top and fold it over and then use tapcon's to secure it.