Chimney install question...silicone seal?

[tfdchief]

Question. I have just finished installing a Selkirk SuperPro Class A chimney. The directions say to use high temp silicone to seal the roof flashing to the Class A chimney (didn't actually see that until after I was finished). I used siver silicone caulk to seal the flashing to the chimney, so that it would not show. Unfortunately, it was not high temp and I have checked since, and cannot find silver colored high temp silicone......rust, black, blue, but no silver. All of these would look like crap. I don't want to undue, scrap and re-caulk with those colored silicones. I just can't believe that a Class A chimney is going to get that hot at roof level.
So, anyone with experience with this? Thoughts?

Thanks, Steve

 

[Wade A.]

That would depend on a number of factors, I'm thinking, like how long is your chimney run, outside temps, how hot a fire, etc. ? Thing is, you'll not know that your caulk has melted away until rainwater starts to pool on your ceiling. You could always build a hot, hot fire on a warm day and get up to the attic and check it. I understand the aesthetic considerations, but really, you're talking about a seam that only a sparrow (and you) are likely to pay any attention to. I'd say that your best and easiest solution is get some high temp silicone and run a bead around and over your existing seam....save yourself a lot of headaches. Then, get some silver paint. Just my $.02......

 

[double-d]

Steve
I've been in the aviation and auto industries and don't remember a silver high temp silicone. If it exists, you'll find out here. I'm not sure how high your stack is, but doesn't the Selkirk pipe allow it to be within 2" of combustible materials, so I would guess at that height you wouldn't be talking about that high of a temperature at the flashing.

 

[Lumber-Jack]

I wouldn't worry about it, it's not going to burst into flames. However the worst that might happen is it might degrade over time and in a year or to you may find you need to redo it, if so you can choose to redo it with some high temp stuff or the same stuff you used and just keep redoing it every year or so.

PS. I used bright red "gasket" silicon on my chimney flashing and you can't even see it from the ground.

 

[begreen]

You want a generous bead where the storm collar contacts the pipe. Regular silicone is rated to something like 400ºF. The surface of the class A pipe is not going reach even half that temp. It's fine as long as it is a good grade of silicone.

 

[Wade A.]

BTW.....a nice job of work, by all appearances.

 

[tfdchief]

You want a generous bead where the storm collar contacts the pipe. Regular silicone is rated to something like 400ºF. The surface of the class A pipe is not going reach even half that temp. It's fine as long as it is a good grade of silicone.

Thanks BG, that is exactly what I thought. I will keep an eye on it for a while as I do everything else. :smirk:

 

[begreen]

I peeled off the GE silicone seal when I removed the old selkirk flue system. It was still doing fine after 10 years of sun, wind and rain.

 

[tfdchief]

BTW.....a nice job of work, by all appearances.

Thanks pb

That would depend on a number of factors, I’m thinking, like how long is your chimney run, outside temps, how hot a fire, etc. ? Thing is, you’ll not know that your caulk has melted away until rainwater starts to pool on your ceiling. You could always build a hot, hot fire on a warm day and get up to the attic and check it. I understand the aesthetic considerations, but really, you’re talking about a seam that only a sparrow (and you) are likely to pay any attention to. I’d say that your best and easiest solution is get some high temp silicone and run a bead around and over your existing seam….save yourself a lot of headaches. Then, get some silver paint. Just my $.02…...

If I would have thought about it for 2 seconds, or read the directions closer, I would have used the high temp and not worried about the color, but, I didn't....so the post. :smirk:

I wouldn’t worry about it, it’s not going to burst into flames. However the worst that might happen is it might degrade over time and in a year or to you may find you need to redo it, if so you can choose to redo it with some high temp stuff or the same stuff you used and just keep redoing it every year or so.

PS. I used bright red “gasket†silicon on my chimney flashing and you can’t even see it from the ground.

Thanks CL. Love the video! You are fast!

 

[tfdchief]

Steve
I've been in the aviation and auto industries and don't remember a silver high temp silicone. If it exists, you'll find out here. I'm not sure how high your stack is, but doesn't the Selkirk pipe allow it to be within 2" of combustible materials, so I would guess at that height you wouldn't be talking about that high of a temperature at the flashing.

Yes, 2" clearance to combustibles. And I agree, just looking for agreement from the troops.

 

[tfdchief]

You want a generous bead where the storm collar contacts the pipe. Regular silicone is rated to something like 400ºF. The surface of the class A pipe is not going reach even half that temp. It's fine as long as it is a good grade of silicone.

Just as a follow up, I looked up the technical info on the silicone I used. It clearly states that "once cured it is uneffected by temperature extremes (-40 °F to 400 °F )" http://www.dap.com/docs/tech/00000683.pdf So, as usual, and again, BG is right on! This site is such a wealth of knowledge. I'm not worring about it anymore. If my chimney gets over 400 surface temp. at roof level, I think I will have bigger problems than the silicone seal around the storm collar and roof flashing :ahhh: