Re: Roofing silicon?
like the standard silicone you get down a DIY store
http://www.ukfixings.com/product/342/203/Everbuild-Stixall,-MS-Polymer,-Adhesive-_and_-Sealant-Box-12?gclid=CKfxpNCMhtICFQ5mGwodPpMA7w
industrial grade is a lot better, and you use it to seal breaze blocks too, to make them water proof and less likely to crumble
to cut the story short, some adhesives can handle temperatures of upto 600c
http://www.masterbond.com/techtips/why-use-silicone-adhesive