Georgia Roof Guide

What problems cause metal roofs to leak?

Short answer. Metal roofs most often leak at exposed fasteners whose rubber washers have dried out or backed out, at panel laps and seams, at trim such as ridge caps and sidewall flashing, and around pipes and other penetrations. Condensation under the panels, rust at cut edges, and installation errors such as using panels below their minimum slope account for most of the rest.

Fastener problems

An exposed fastener roof can have thousands of screws, each sealed only by a small rubber washer. Sun hardens the washers, and daily expansion and contraction work screws loose. Overdriven screws crush their washers on day one, and underdriven ones never seal. Periodic fastener maintenance is normal for this style of roof.

Seams and laps

Side and end laps need sealant tape between panels. Missing or misplaced tape lets water wick in by capillary action, especially on low slopes where water moves slowly.

Trim and transitions

Ridge caps without foam closures let wind-driven rain blow underneath. Sidewall and endwall trim pulls away, and chimney flashing is harder to detail on metal than on shingles.

Penetrations

Boot cones crack in the sun, and pipes set across ribs dam water uphill.

Condensation and corrosion

Panels over open framing drip when humid Georgia air meets cool metal; on homes, underlayment below the panels prevents it. Cut edges and scratches rust first, and copper or lead in contact with galvanized or Galvalume steel corrodes the panel.

What is not a leak

Oil canning, the wavy look in flat areas of panels, is cosmetic. Stains that appear on cold mornings without rain are usually condensation, not a hole.

For the bigger picture, see metal roofing in Georgia and common leak causes.

In depth

What causes most roof leaks?Where roof leaks really start: pipe boots, wall and chimney flashing, nails, valleys and lifted shingles, plusWhy do pipe boots leak, and how are they fixed?How plumbing vent pipe boots fail on Georgia roofs, the installation mistakes behind most leaks, repair collarShould you replace skylights when you replace the roof?Why a roof replacement is the best time to replace or reflash skylights, what warranties require, energy crite

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