I was covering up the oven for oncoming rain. When I tried to take the chimney off (it’s a 4’ one), the entire base came off with it.
What is the correct procedure for putting it back on?
Also I noticed 4 holes in the flashing and wondered if I should screw the base to the fire bricks?
Thanks
Yeow! Not a good feeling, Brian, but not hard to fix.
You are in an area where it rains, at least occasionally, so I would recommend that you not simply reaffix the stack base to the chimney. You need to add a mortar “crown” to top the oven’s chimney first.
I wrote about it in this post from earlier in 2023:
Your situation isn’t as dire, because it looks like your chimney is in good shape. So I’d use a sharp blade (like a widget or glass scraping tool) to scrape off the old silicone sealant. Then follow the instructions in the thread above to build a crown to cap the chimney. It will cure as you build new fires, so just let the mortar set to the touch, then reattach your chimney with new silicone sealant per the oven instructions.
As for attaching it, yes, you can use TapCons to attach the DuraTech base to the chimney crown. @BrickWood says that he stopped including that step because some builders were careless and ended up cracking the chimney brick!
So, use a relatively small TapCon anchor/bolt set, drill very carefully—straight down, and to the exact depth specified on the package—and don’t over-torque the bolt. The silicone is still doing the primary job of attaching the base to the crown, and the TapCon anchor is stabilizing it.
I feel more confident recommending this to you because you will be adding the missing crown, which will help keep the underlying firebrick from cracking. But again, please be careful.
Good luck, and please post with further questions and photos of the completed repair, Brian!
I had the exact same problem. Here’s the link to my fix using Tapcons to secure the Chimney Cap
Two and a half years later and I’ve had zero problems.
Thanks for advice. It will probably be a while before I get to it. (Oven is normally dormant for a few months).
I’ll report back.
What i did with my chimney is secure it with some masonry screws and I also used some high temp adhesive around the metal also
Just wanted to follow up and let you know that the re-attachment went well.
I didn’t use the Tapcons as the shortest I could see were 1/1/4" and I just didn’t want to take a chance of something happening when drilling. I still have the option to do it.
I take the 4" chimney extension off every year when I cover up for winter. My guess is that the twisting on and off of that is what weakened the base. In the future I’ll enlist extra hands so I can hold the base steady while taking off the extension.
Again, many thanks for the help.
That’s such great news, and thanks for following up Brian!
Well, the chimney base came off again this year as I was getting ready to cover it up for winter. I know I’ll be able to fix it but it’s something I don’t want to have to do every year. (The first 4 years didn’t have the problem).
I think one reason this happens is that I have a 4’ chimney and just trying to unscrew it from the base puts too much pressure on it.
So I’m thinking:
Thanks
Dang!
You could use a high-temp lubricant on the base. Molybdenum or graphite sprays would both work fine. Moly lubes are used in automotive applications and aerospace work. But there are also consumer sprays available for about $10, including well-known brands like WD-40 and 3-in-1 (not their general-purpose formulas, but those specifically marked “specialist” and molybdenum-based). Search for “high temp dry lubricant” and you’ll see lots of options.
A high-temp silicone lubricant would also work, but it starts to break down above 500°F temperatures and I think that’s part of the issue with the orange or red silicone adhesive sealant that is unique to your situation. You should still use that for the base, but I think something with a higher service temp for lubricant is what you need here.
Moly is not particularly water-resistant, but your first riser above the base overlaps the socket, so it should be protected well enough. While it is not toxic to humans in small quantities, you should protect the inside of the socket and the opening so it doesn’t spray down on your hearth. You could also use any of these products to lube the pivot rod for the damper.
I recall you weren’t crazy about the TapCons, but your practice is unusual because you’re actually removing the stack at the end of each season. That’s completely justified given your local climate, but I think experience has borne out that you need them for their anchoring effect. Between the fact that you’re using them in a horizontal (non-weight-bearing) application, and that they will be sealed with the orange silicone, I think you will be fine. (I’ve been thinking about it ever since our previous conversation, too!)
Mark the holes carefully, use exactly the right size masonry bit called for by TapCon for the anchors, and don’t over-tighten them.
I hope this helps, and as always keep us posted, Brian!
Do you really need to keep removing it? I just cover my oven in poly and it just wraps around the damper and I overlap it at the oven opening. The oven stays dry and the poly is cheap.
I have a 4 ft chimney.
However, I am considering putting a hole in the tarp then getting a different one for the chimney.
My chimney is at least 3 feet, and since at the front of the oven it’s no problem wrapping around its base.
I used tapcons. FWIW, I remove the stove pipe every year before I tarp the oven and the base is as tight as when I installed it. I only have the damper and the cap though…
Thanks all for feedback (so far)!
@Brian … way up in this thread you noted that you were reluctant about TapCons because the shortest you found were 1¼ inch. As I think about it, that’s really not far into the brick at all. They have a specialized role here, as @kgondoly can affirm, because all they are doing is keeping the base from twisting or pulling away when you twist the duct on or off. They would be bearing very little load, even if you had hurricane-force winds, because the chimney is round and narrow and they will offset loads at the four corners.
And not for nothing, but so far you’ve had this happen only when you’re removing the stovepipe intentionally. Because of your application, you need to think about the outcome if the silicone failed while you were cooking.
Again, it’s your call in the end, but considering your past experiences I would strongly recommend using them. I still believe, looking again at your original photos, that you need to crown your chimney, but I understand it’s more mortar work than you might want to do.
