Diagnosing a leaky metal roof

leaksroof

We purchased a 60 year old house a year ago, and the builders report suggested no issues.

The main roof of the house is tile over wooden rafters, and the attic space is dry.

There is an extension, done very early on in the life of the house, extending one of the bedrooms beyond the main roof, and the extensions roof consists of an almost flat metal roof, starting underneath the existing roofs eaves and extending outward away from the house. There is a slight (5 degree perhaps, without getting a protractor out) pitch to the extensions roof.

The extensions roof consists of flat metal sections interspersed with rafters on top of the roof, and these are also covered in metal.

The roof has a leak on one half of it, but we cannot seem to find any obvious place externally where the leak may be when inspecting the roof externally. We cannot inspect the roof internally, there is no cavity of note. Externally, while the roof can do with a repaint, it looks in fair repair to a non-expert.

Can anyone suggest approaches to track down the leak, or general approaches to mitigating such leaks in these style roofs?

Best Answer

When I try to track down a leak, I start near where the leak is “showing” in the house and spray a garden hose near the “bottom” of the roof. I keep the water shooting slightly “up” the roof (like a rain storm) and let it run for 15 - 20 minutes in one area. (Yes, this takes a long time.)

I position someone inside to see if (and when) it starts leaking.

I then slowly work my way up the roof until it leaks. Be patient.