CBD's Silbernagel Chimney Cap page

The detailed custom fabrication of a 33.5" wide x 39.5" long copper chimney cap (1-06)

Here is what we made with the design help from the client: Todd Silbernagel in Dundee Oregon, just Southwest of Portland Oregon. It was designed to cover a wood frame chimney case that was covered with a stucco facing, and designed to support the aluminum bathroom exhaust and plumbing vent. There is not going to be any heat involved. This was just the best way to not have lots of small pipes coming out of their tile roof.

It took about 65.2 square feet of copper to make this chimney cap, and weighs in at 81lb plus 24lb for the lower wood base frame, and another 6lb for the upper wood frame to screw the roof onto. Even though it has very few visible rivets it is so sturdy that when lifting it up on one corner it seems to have no detectible flex to it. Made as seamless as possible. This chimney cap sits down to cover the top 2" thick wood frame that was screwed into the studs and another 4" of the stucco facing over the wood. It took 5 to 6 full days just to build this cap in our shop.

The final cost delivered and installed was $2,030,
See below for the 60 other photos of this custom fabrication.

The chimney top edge was just vertical studs, plywood and stucco. This shows the wood base frame that will be screwed down to the top edge of that chimney box and the chimney cap will be sitting on. It is made from a set of 8 alternating boards that are pre-primed 5/4 x 6. It was glued together with Gorilla clue and held together with a couple dozen screws. Then angle cut to the pitch of the copper base seen below.

The cap angles need to be carefully calculated so there are no errors or unexpected complications. We have to think several steps ahead, like working out the problems of a Rubixs Cube. If we are in error, we may ruin some very costly copper material. This shows three sides of the base bent longwise, and then having the corners formed. The lower section design has been drawn out on the copper on both the film side and the underside, since there are several bends and cuts to be made in both direction.

Our work table is 4' x 8'. The sheet of copper shown come 10' long and 3 feet wide. Keep in mind that the copper sheet metal still has a protective clear plastic film over one side that will be used for the outside of this copper chimney cap to protect it from finger prints and scratches. The red print will come off with that film. It is to be pealed off after installation. It is careful work to bend and fasten the corners here so they are perfect right angles before riveting them together. The cuts in the inside of the corners are also tricky to calculate so it will fit together just right. Here is the base section getting the flue pan secured in place.

This pan has to support two separate vents and be able to seal out hard blowing rain, and shed that rain out to the sides. I have made this with a pair of cross bends to raise the centers where the vents will go up through the copper pan. I also made a channel for the copper screen to seat into.

We then cut the tabs to bend up that will be clamped against the flue pipe. with this copper straps and the stainless steel bolts with lock nuts. In the last photo I had pealed off the protective film off the pan. That is why it looks different.

The middle section body of this cap that will support the roof is one piece for all 4 sides (as seen here), with only one seam. It is only 15" high. We then seamed the frame together with a pair of 1" overlapping seams over the back corner.

Here is the middle section frame standing up to finish riveting the arch wells in place.

This is the assembly of the roof frame to go over the arched screened area. It was made in only 2 separate section and sealed together with overlapping seams.

This shows the corner piping trim mounted just below the arches over all 4 sides of each corner post. Since there is no heat involved with this chimney cap, we made another custom wood frame to secure to the middle section and screw the roof onto. Allowing for easy removal for future maintenance.

This shows the two different angled wood frames we made for just under the roof and under the base.

This shows the vent holed we cut into the copper pan and bent the flanges down for the clamps. I am attaching the middle section to the base and sealing the corners with a clear caulk.

This is showing the screens area bent into shape over the arches and attached securely with rivets to keep out any pests.

Here is some detail shots of this chimney cap in daylight of the finished chimney cap from several different angles to get a good look at it. It is not perfect at close inspection, but the client said it turned out better than he had imagined. That is one of the best compliments we could get. Our main focus is to make it durable.

The roof of the house has clay tile roof, so the owner wanted to minimize the pipe vents needing the punch through the roof, so he organized all the pipe vents and house vents from the bathrooms and kitchen to connect in the center and go up through this one area in the top of the roof. Then contracted us to make this nice vented screened roof cap.

Here is the chimney box from up on the roof as we show the installation. The flashing just over the roof is copper as well, and shows the tarnish from just a few months.

The first step was to try an level off the stucco using a chisel. The stud placements were measured for the drilling of the screw holes in the base frame. Then attach the base frame to the top with long 3.5" deck screws you will see in the first photo sticking up out of the wood.

They fitted the vent pipes up through the pan after we had it secured in place. Then caulk the pan and secure the pipes with the collar I made with the stainless steel bolt.

The black plastic pipe was trimmed a little lower before the roof was installed and screwed down tight and the plastic film finally pealed off.

Here is more photos of the house with the finished copper chimney cap in place

Here is their splendid view from the back of the house.