Frost in attic

[jcampbell (Jeffrey Campbell, CMI)]

I think we address most of the possibilities in the post… without seeing more photos of what is going on with insulation, ventilation, VB, bath exhausts, scuttles, etc… we have a pretty good ideal of what could be the problem…

[Ed_Fako]

@jallingham

What am I missing. What does insulation have to do with it? Lack of vapour barrier - yes, lack of ventilation - yes, but how does lack of insulation lead to high humidity in the attic.

The lesser amount of insulation would allow more warm air, which also contains an RH content to invade the attic region.

Although the tightly sealed attic possibilty is a viable, yet costly undertaking on an older existing structure, it certainly could be one of the recommendations made.

Alternatively, I saw no notation of the Intake Ventilation, other than a casual comment that the ventilation"Seemed" sufficient.

Was ther any blockage of the soffit vents from the insulation?

Were there any insulation baffle vents, which would allow the Intake Air Flowage to progress into the attic?

Since this was a Hip Style Roof, what types and amounts of Exhaust Ventilation were provided for?

Commonly, on a hip roof, people rely on a Powered Attic Ventilator, which usually only contains a thermostat for interior heat detection.

A working PAV for the winter months, would also have to have a Humidistat hooked up for proper vapor exhaust and good moving air flowage.

Ed

[nwagner (Nick Wagner)]

Scott, is that sap I see along the rafter? If so, it looks like there may be a ventilation problem. Baking of sap out of rafters is often an indication of the attic overheating during the summer …

InterNACHI®️ Forum

[jevans (John Evans)]

CertainTeed offers a free “Principles of Attic Ventilation” online course that is very informative.
http://216.83.181.215/elearning/certainteed/resources/index.jsp

[shand (Scott A. Hand)]

It does appear to be sap…frozen sap.

[jwarner (Joel T. Warner)]

Scott,

This is an indication of both poor insulation and poor ventilation. Unless you see bathroom vent that is not directed the exterior and discharging or leaking into the attic area.

The warmer conditioned air in the interior rooms below is escaping into the attic where it is met by the colder air in the attic and it condensates. The condensation then freezes on the nail tips and anything else it settles on. Looking for rusted nail tips in the summer inspections will help determine this problem when the frost is not present. Hope this helps.

[jallingham (John Allingham)]

@jwarner

Scott,

This is an indication of both poor insulation and poor ventilation. Unless you see bathroom vent that is not directed the exterior and discharging or leaking into the attic area.

The warmer conditioned air in the interior rooms below is escaping into the attic where it is met by the colder air in the attic and it condensates. The condensation then freezes on the nail tips and anything else it settles on. Looking for rusted nail tips in the summer inspections will help determine this problem when the frost is not present. Hope this helps.

Why poor insulation?