Ventilation in attic

[Buck Hartley, CMI]

I found these signs in an attic today. Stains on the insulation and rusty nails above the stains in the roof sheathing. Is this a sign of poor ventilation in the winter?

Thanks!

[David P. Valley]

Originally Posted by bhartley

I found these signs in an attic today. Stains on the insulation and rusty nails above the stains in the roof sheathing. Is this a sign of poor ventilation in the winter?

Thanks!

These nails are rusting due to the living area heat breaching up through the ceilings and into the attic cavities during the winter months from inadequate insulation depths. This heat loss causes an ice build up on the hardware and it will eventually melt and drip.

Massachusetts requires R-39 value.

Ventilation could also be a contributing factor if insulation is adequate.

[Kenton H. Shepard, CMI]

Dave, how is heat causing ice buildup?
Since it looks like all the nails are rusted, it looks like high humidity to me. I'd say moisture from the house rising into the attic with heat.

Check bathroom exhaust terminations carefully which you see this condition. Here's one I dug up.

[David P. Valley]

Originally Posted by kshepard

Dave, how is heat causing ice buildup?
Since it looks like all the nails are rusted, it looks like high humidity to me. I'd say moisture from the house rising into the attic with heat.
Check bathroom exhaust terminations carefully which you see this condition.

Kenton,

I see this daily in the winter months.

Please don't insinuate that I'm wrong.

[Buck Hartley, CMI]

The bathroom exhaust fans terminate in the attic. Here is another photo of the sheet rock, this area is framed for a whole house fan there is no insulation in this area.

[James F. McKee]

You answered your own question Buck....the bathroom exhaust fans terminate in the attic....there is your moisture Sir...or at least a significant part of it...imo...

[David P. Valley]

Originally Posted by bhartley

The bathroom exhaust fans terminate in the attic. Here is another photo of the sheet rock, this area is framed for a whole house fan there is no insulation in this area.

The drip stains (on the exposed drywall) only indicates that the heat escaping from below this uninsulated cavity is causing excessive dripping from the frost build-up on the roofing nails.

[Marcel R. Cyr]

I agree with you Dave on this one, see it all the time up here.

Excessive heat loss due to poor insulation and poor ventilation to keep the attic cold and suplemented with bathroom exhaust vented in the attic can form frozen condensation on the underside of roof sheathing up to 1/4" thick in some cases.
When the sun comes out for a while and temperature rises, it starts dripping and once dry, the sheathing shows the signs of rust from the nails.

[Buck Hartley, CMI]

Thanks! for the help.

[Larry D. Kage]

Yes, but it is a dry heat.

I wonder where the frost on the nails comes from.

[David P. Valley]

Originally Posted by lkage

Yes, but it is a dry heat.

I wonder where the frost on the nails comes from.

Larry,

The winter months.

[Larry D. Kage]

Originally Posted by dvalley

Larry,

The winter months.
Attachment 29758

I'm not following you. Where, during the winter months, does the moisture for the frost on the nails come from?

Thanks.

[David P. Valley]

Originally Posted by lkage

I'm not following you. Where, during the winter months, does the moisture for the frost on the nails come from?

Thanks.

Refer to my post#2

[Larry D. Kage]

Originally Posted by dvalley

Refer to my post#2

That gets us back to my post # 10.

The moisture is coming from somewhere.

[Joe Funderburk, CMI]

How do you know the roof isn't shot and chronically leaking at the nails?