If the coil is located on the back of the zipper instead of the front it is an Invisible Zipper. Metal zippers consist of individual metal teeth. They are typically made from nickel, brass, aluminum and manganese.
Cost of Repair. The cost to re-line a chimney can be very expensive! Repair costs generally range from about $2000.00 to $4500.00 per flue or more! In a Real Estate transaction, you may have the opportunity to negotiate defects that are disclosed as part of the inspection process.
I had 2 fireplaces and a 3 flue chimney built when I built my house and the cost was $12,000. It is 9ft wide and 3ft deep faced on 3 sides all the way to the roof and then faced on four sides above the roof with hand cut stone. It is a thing of beauty.