Frost On Roof Sheathing

When moisture gets into the attic it condenses on the roof sheathing in the form of frost.

Frost on 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. Frost and ice forms in attics when warm humid air accumulates and condenses on the underside of your roof sheathing. A little bit of frost forming is not unusual after really low nighttime temperatures and it isn t a huge problem if it is able to melt and evaporate so that the wood can dry. 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.

If the morning sun directly hits your home and not your neighbors lack of frost may just be attributed to the sun s heat. Can sun get to the roof you will have either frost or water collecting. After spending a lot of time on gba i believe the best approach is to put exterior foam on the roof sheathing as we are looking to replace the shingles this summer due to the damage that was caused to the shingles to remove the ice dams and the fact that the builder never applied any ice water guard. Warm shingles don t allow frost to form as readily as cold shingles.

That heat then conducts up all the way to the shingles. The problems you pointed out are certainly real and need repair but getting the underside of the decking frosted requires vapor. Melting frost can lead to deteriorated roof sheathing mold on the roof sheathing wet insulation and water stains on the ceilings. That warm air makes contact with the roof deck and warms it up.

Before getting concerned you need to make sure the lack of frost is due to the roof itself and not from outside forces. Several online posts mostly from american sources say that any frost is not normal and signals impending doom. When it reaches the cold surface of the roof sheathing and framing it turns to frost. Depending on the temperature and the insolation ie.

And here s the clincher. When the moisture gets into the attic it condenses on the roof sheathing in the form of frost. Left unchecked frost in an attic can lead to serious mold and decay. Once in the attic it warms the air over the living space.

I have no bathroom vents or anything bad like that sourcing moisture into the attic. The nails there are icy too but the rest of the roof sheathing and trusses look fine. That s about it pretty simple. However if nothing is different about your home compared to your neighbors you may have a problem.

Frost itself doesn t do any damage but once it melts things get wet and then damage occurs.