Frost On Roof Sheathing

Warm shingles don t allow frost to form as readily as cold shingles.

Frost on roof sheathing.

Several online posts mostly from american sources say that any frost is not normal and signals impending doom. Frost and ice forms in attics when warm humid air accumulates and condenses on the underside of your roof sheathing. In the parlance of building scientists these cold wooden house parts make up a condensing surface much like a cold glass of ice tea beads with water on a hot summer day. However if nothing is different about your home compared to your neighbors you may have a problem.

And here s the clincher. Melting frost can lead to deteriorated roof sheathing mold on the roof sheathing wet insulation and water stains on the ceilings. That s about it pretty simple. Frost itself doesn t do any damage but once it melts things get wet and then damage occurs.

When moisture gets into the attic it condenses on the roof sheathing in the form of frost. One theory is that the walls have been demo s for a 2 3 week period on the interior and the heat from the interior is mixing with the cold air from the exterior creating frost on the inside of the sheathing. The problems you pointed out are certainly real and need repair but getting the underside of the decking frosted requires vapor. That warm air makes contact with the roof deck and warms it up.

If the morning sun directly hits your home and not your neighbors lack of frost may just be attributed to the sun s heat. Once in the attic it warms the air over the living space. Can sun get to the roof you will have either frost or water collecting. My question is is a little bit of frost normal in canada.

When it reaches the cold surface of the roof sheathing and framing it turns to frost. Depending on the temperature and the insolation ie. When the moisture gets into the attic it condenses on the roof sheathing in the form of frost. I have no bathroom vents or anything bad like that sourcing moisture into the attic.

Before getting concerned you need to make sure the lack of frost is due to the roof itself and not from outside forces. Left unchecked frost in an attic can lead to serious mold and decay. The frost itself doesn t do any damage but once it melts things get wet which is when the damage. The nails there are icy too but the rest of the roof sheathing and trusses look fine.

That heat then conducts up all the way to the shingles.