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Mechanical joining, soldering and fasteners · Lesson 2 of 4

Mechanical joining, soldering and fasteners: materials, standards and design constraints

Copper, coated copper, galvanized, stainless and zinc each solder differently; Galvalume and aluminum are not soldered. Fluxes, fastener compatibility, and why the project spec decides.

You will be able to: Say which sheet metals can be soldered and how, which must not be, which flux and fastener metals suit each, and which limits come from CDA, manufacturers, owner standards and the project spec.

12 min · 12 slides · 11 questions

All lessons in this module
Slide 1 of 12

Copper, the classic soldered sheet

In the CDA details, soldered lap and flat lock seams are only for copper up to 20 oz.

For heavier copper, one option is a lap that is riveted and soldered, with the rivets carrying the load; CDA states no weight limit for it.

CDA advises against continuous, long runs of soldered seams: soldered seams are permanent and can develop stress fractures.

Sources

Videos for this lesson

What this video shows: CDA, narrated by Larry Peters, shows a flat seam soldered joint for slopes up to 3:12: the preparation, the tools and the steps.

Video: How-To: Flat Seam Soldered Joint by Copper Development Association, on YouTube. Chosen from the video's published description.

Glossary

50-50 solder
Tin-lead bar solder, half tin and half lead, the common solder CDA names for uncoated copper.
Galvalume
Steel sheet with an aluminum-zinc alloy coating; its makers do not recommend soldering it.
Zinc chloride flux
An acid flux typical for roof soldering; corrosive to skin and eyes, and its residue must be washed off or neutralized.
Muriatic acid
Hydrochloric acid; GSA uses it on galvanized sheet as cleaner and flux, and WJE warns its residue corrodes stainless.
Compatible fastener
A fastener of the same metal as the sheet, or one at least equal in corrosion resistance.