How to cure millpac at flashing and storm collar

[blondemommy]

I have used three different kinds of sealant at the storm collar, and top of the flashing for my fireplace chimney. I live in Florida so it rains daily. This stuff just turns to mush and runs down the chimney into the house once it rains. How do I get it to harden?
I just bought some Millpac at the advice of a friend. Is this going to do the same thing? Should I use a heat gun to cure it around the storm collar? I would really like to close this fireplace up, but I am afraid it will start leaking again as soon as I do...HELP!

 

[webby3650]

Milpac isn't intended to be used outside like that. All you need is Silicone. It's available at any and every hardware store, no need for anything special. High temp isn't even needed, it will never get hot enough to affect silicone up there on the roof.

 

[bholler]

yeah mill pac never hardens that is why it is good for pipe seams but not good for flashing. Silicone is good we use geocell 4500 it is great stuff. But at this point you will need to clean all the mil pac off before using anything else.

 

[blondemommy]

bholler: I have some high heat silicone caulk (actually several tubes) will this work? Or does it need to be specifically for chimneys?
Thanks again!
Mary

 

[webby3650]

Milpac isn't intended to be used outside like that. All you need is Silicone. It's available at any and every hardware store, no need for anything special. High temp isn't even needed, it will never get not enough to affect silicone up there on the roof.

 

[begreen]

On the roof you want a good silicone like GE Silicone II that is designed for exterior use. I think it has higher UV resistance.

 

[blondemommy]

Thanks guys!
:0)

 

[Highbeam]

Pick a color that wont look dumb. White looks bad.

 

[webby3650]

Pick a color that wont look dumb. White looks bad.

Yes! So does red. I see red occasionally, its hideous.
I use silver, unless the pipe is painted black. Then of course I use black silicone.

 

[begreen]

I've only used clear silicone on storm collars. Took one apart after 12 yrs of service and it was still bonding well.

 

[velvetfoot]

A generic comment on silicone caulk:
I got a tube that was just a little past is Use By date. It took a really, really long time to cure; maybe months. So make sure the tube is fresh.