Even though chimney flashing is related to roofing, rather than taking up so
much room on the "Roofing" page, this separate page is added.
With copper roofing, the first layer of flashing involves some soldering, and that
will not be covered here. This is a method we used to flash chimneys
penetrating a Cypress shingle roof.
Pictures are thumbnails. You can click on any picture to get a full sized version.
No exposed fasteners on the roof planes are used.
No. 6 solid copper "ground" wire was formed into
loops to be held down by shingles on top of the
bends. Ends were left sticking up at the same
measurement down from the chimney.
Shingles were made the right length, and stapled
onto the copper wire. Staples are 2-1/2" long
Wire locations were marked on the first layer of
flashing, and holes were punched for the wires
to come through.
The wires were bent down into the gaps between
the shingles holding the loops with a punch and
hammer. The wire is too stiff to make tight bends
by hand. This left the fasteners holding these
shingles up under the flashing, and none exposed
to the sky.
The top layer of flashing, or "counter flashing" will
be held on with Bronze machine screws and
washers threaded into threaded lead anchors.
These anchors, called "caulk-in anchors" have a
threaded insert formed in a stiff lead alloy tapered
shape. On the outside of the tapered threaded
insert is a softer lead sleeve. The lead sleeve will
get pounded in tightly packed around the tapered
These inserts require a special tool for installation.
In the center of the tool is a threaded "bolt" that gets
threaded into the tapered insert with a knurled knob.
That knurled knob is loose inside the tool attached
to a hardened tube that matches the diameter of the
outer lead sleeve.
The insert is threaded onto the tool, placed in a hole
in the brick, the knurled head is pounded with a
hammer which then compresses the outer lead
sleeve. After packing the lead tightly around the
threaded insert, the knurled knob is unscrewed,
backing the tool out of the insert.
It leaves a nice little threaded insert neatly in a hole
in the brick. It's now completely mechanical, and
not dependent on an adhesive's life for longevity.
Now we need to mark the exact location of this
threaded insert behind the counter flashing (top
layer of flashing). You didn't think we could do this
job without duct tape, did you?
Painters "duct" tape for masonry has a thick
adhesive to stick to masonry that doesn't leave
residue. A small piece holds a Rare Earth ball
magnet against the threaded insert.
In this picture you can also see the slot that has
been cut for the counter flashing to turn into. It's
angled down to the outside to carry water over the
The counter flashing is held in place, and other
Rare Earth ball magnets quickly find their mates
The locations for the holes are marked, and holes
punched for the Bronze machine screws.
This is an 1850 house. While they would not have
done chimney flashing exactly this way, the counter
flashing was folded by hand, instead of with a
bending brake which would have made it look more
modern and industrial.
The chimneys on this house have left signs of
leaking, probably since the house was built in
1850. They won't leak again.
the chimneys, we build a "Cricket"
with a little standing seam copper
roof. Going up the valleys of the
layered, so those shingles
become a part of the cricket
structure, parting water coming
down the roof to the sides of the
much less likely for snow, or
accumulating leaves to hold water
above a chimney, which will find a
way into the house.