How to insulate to prevent condensation on a metal roof

Updated February 21, 2017

Metal roof insulation increases the temperature of the inside surface of the ceiling. This, in turn, prevents moisture condensation on the metal roof. If you are experiencing mould and mildew growth, damp spots on your ceilings and walls, or musty odours, there is a good chance that your metal roof is not properly insulated.

Lay the insulation loosely over the purlin or truss structure (the horizontal framework of beams helping to support the roof). The panel attachment, in combination with the purlin or truss structure, will secure the insulation.

Pull the insulation so that it extends over the top plate of the wall.

Secure the insulation to the top plate of the wall with a staple gun so that cold air cannot come up between the top plate and the insulation. If you experience extensive condensation in the future, chances are the insulation has detached from the top plate.


Insulation is only one step in preventing condensation on metal roofs. Other important steps include lowering household humidity, increasing ventilation in the attic and managing external water.

Things You'll Need

  • Roof insulation
  • Staple gun
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About the Author

Thomas King is a graduate of the University of Pittsburgh School of Law where he served as managing editor of the "Pittsburgh Journal of Environmental and Public Health Law." He currently lives in Aberdeen, Washington where he writes and practices law.