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Bitumen Membrane for Chimney flashing?

I just received a quote from a roofer to re-roof my house (tearoff).

They are proposing to "Flash Chimney with a 4.2mm layer of Granulated Modified Bitumen² Membrane material, and seal with Solar Solar Seal® 900 Sealing Compound".

I am only familiar with metal chimney flashing (galvanize steel, lead, copper). I certainly want the most durable as well as leak proof flashing material.

Is Bitumen Membrane appropriate for flashing a chimney? If so, is it better, worse, more expensive or less expensive (short-run and long run)?


Re: Bitumen Membrane for Chimney flashing?

does the quote state if the self sealing membrane is the finished flashing or a base layer. its becoming more and more common to use it for all roof penetration points. from there the metal is added for the final touch

Petty Roofing, Boise
Re: Bitumen Membrane for Chimney flashing?

Metal flashing is superior to a bitumen flashing around a chimney in most cases. Ideally, the chimney should have metal flashing mortared into the brick or blocks that comes downward toward the roof deck. The roofer then installs metal flashing over the new roof that slides under the chimney flashing. A granulated bitumen material would also work under the chimney flashing. Using the bitumen as a stand alone flashing can work allright if the brick or block has sufficient strength to withstand the installatin of a termination bar that screws through the top of the bitumen and holds it in place and also provides a bit of a lip for the application of a sealant. Without a termination bar the bitumen material can pull away from the chimney over time.

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