mark yerg
7/11/2005
I am flashing around a masonry chimney(metal roof over exsisting shingles) The old flashing was put in between courses of block. I intend to cut a groove with a masonry blade and fit new flashing into that. What type of caulking works well with metal to masonry? I have been using the mnfctr's recommended butyl rubber tape mastic and tube caulk for all hidden seams. On exposed seams this type of caulk stays sticky all the time and attracts everything that lands on the roof-leaves, bugs etc. Can I use a silicone base caulk for this type of seam-Bathroom vents, roof jacks etc.?
Todd Miller
Classic Products, Inc.
7/11/2005
Mark, I would suggest using roofing cement or underlayment to separate between your metal flashing and the masonry. As far as a sealant, the terpolymer butyls tend to get a pretty hard skin ... they stay supple but solid on the surface. Another option would be a urethane sealant. Silicones may not stick well over the long term to the paint finish on your flashing metal.
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