How long does copper flashing last?

How long it lasts

In its environmental product declaration (EPD, 2023) for copper sheet for roofs and facades, Aurubis gives a reference service life of more than 100 years. Building sheet is made as Cu-DHP to EN 1172.

Patina

New copper is shiny. In air it turns brown within days to months, and later darkens. After some years a green patina may form – on the coast it may even be bluish. The patina is a protective layer, not a sign of damage. Manufacturers also offer pre-patinated sheet.

What harms copper

• mechanical damage and badly made seams or soldered joints,
• standing water on flat surfaces,
• badly designed fixing with no allowance for expansion – copper expands (0.17 mm/m per 10 K according to KJG).

What copper does to other metals

Water running off copper dissolves zinc, galvanised steel and aluminium. VMZINC writes that run-off from copper onto zinc must be avoided in all circumstances; Lysaght (per AS/NZS 2179.1) rules out run-off from copper onto aluminium and galvanised surfaces; Lindab’s warranty conditions exclude contact with copper and with water from copper components. Water from copper can also leave green marks on the facade and paving.

In practice: if a chimney or dormer is to be flashed in copper, the gutters and downpipes below it should be copper too.

Cost

According to KJG’s price list (from 11 August 2026), a girth-333 gutter costs €45.59 per m excl. VAT in copper and €4.20 per m in galvanised steel. For this component copper is therefore roughly 11 times dearer. Over a long service life the difference is partly offset by fewer replacements – provided the rules on galvanic action are respected.