If the tin roof sits on top of another material such as wood then you can get a case of wood rot.
Steel roof condensation problems.
Having vents in all elevations of the shed is an effective way of minimising metal roof sweating.
Condensation happens when moisture filled air contacts anything that is below the dew point temperature.
When this happens the tin roof can rust and even warp.
Condensation on metal roofs can be a problem once the weather starts to get cold.
Metal gets cold faster than other items so condensation begins on metal first.
Warm wet air rises and meets the cold roof and cools.
Improper usage handling and storage by installers.
As it cools it can t hold as much moisture.
Changes to the structure s original form that puts tension on or moves the panels.
Essentially condensation occurs at night when the temperature inside a building is warmer than outside.
Inadequate space allotted for thermal expanding and contracting of the panels.
Metal roof condensation especially with a tin roof can cause serious problems when the metal sweats or rainwater collects under the tin panels.
Picture a cloud of moisture floating overhead between the rafters.
The lower the pitch of a metal shed roof and also the deeper the corrugations the worse the problem of metal roof sweating.
Frequent stress from coil slitting cutting and rollforming panels.
It can lead to roof leaks even if rain has not occurred for several days.
That excess moisture ends up as drops of condensation on the roof.
This applies to both the timber and steel trusses.
Although condensation in roofs may not seem like a serious problem it actually is.
Having ventilation holes around the roof at eaves level and in the gable walls allows moisture rich air to escape.
This video shows what a significant condensation problem can look like.