I’ll get straight to the point of this one: use fasteners made from material that is compatible with copper. Brass, stainless steel, and copper, and all commonly used with copper gutters and downspouts. These metals work well together and will not cause a galvanic reaction with the copper that prematurely ages both the fasteners and gutters or downspouts.
Pop Rivets – Best Option For Exposed Fasteners On Copper Gutter Installations
There are two types of copper pop rivets, or blind rivets, readily available to installers in the marketplace: those with a brass mandrel and those with a steel mandrel. The mandrel is the “stem” that is inserted into the rivet gun, and once the rivet is “popped” a small piece of the mandrel remains at the center of the installed rivet head. This will eventually rust. You can easily distinguish between the brass and steel mandrel rivets with the use of a magnet. You can also see the difference: brass mandrels look like, well, yellow brass. Steel mandrels are usually an reddish / orange steel color. Malco, a common manufacturer of miscellaneous sheet metal tools and fasteners, make copper rivets with steel mandrel. Buyer beware. Steel is cheaper than brass, so that is likely why they are made the way they are. If you are ever in doubt about the type of fasteners you are ordering, ask your supplier.
1/8″ Pop Rivets are installed by pre-drilling a hole, inserting one end of the rivet into the riveter and the other end into the pre-drilled hole, then “popping” the rivet in place. There are three ways to pre-drill the hole: with a #30 double sided drill bit, an 1/8″ drill bit, and a zip screw. Let’s start with the zip screw. The hole that a zip screw makes is about an 1/8″. However, it isn’t the cleanest hole so the finished product isn’t ideal. Next best is an 1/8″ drill bit. Get one that’s rated for drilling into metal so they don’t dull too quickly. The hole that an 1/8″ bit drills is the same size as the rivet, so it’s a sometimes frustratingly tight squeeze. Installing copper gutters on a gusty winter day, 20 feet up on a ladder, and wrestling with getting the rivet into the hole is not my idea of fun. The 1/8″ bit will work, though. The best option is a #30 bit, made by Irwin. They are double sided drill bits, so when one side dulls, they can be flipped over. Very convenient, when drilling holes in copper gutters, or any other types of metals, because the bits will dull out. The hole they drill is slightly larger than 1/8″, so there’s no wrestling to get the rivet in the hole.
Zip Screws – Convenient Option for Copper Gutter Installations
Copper coated stainless steel zip screws are a convenient option for copper gutter and copper downspout installations. These screws are of materials compatible with copper. However, I have order copper coated stainless steel zip screws that can be picked up by the magnet in my 1/4″ hex head driver, which is very suspicious. I like to use copper coated stainless screws in areas that cannot be easily seen from the ground. When installing downspouts, it is possible to attain a very clean aesthetic by putting the downspout together with zip screws on the top and back of the downspout so they aren’t seen, then fastening to the wall with op rivets through the pipe band. Keep the rivets on the sides and back towards the wall as far as possible, for the cleanest look.