Roof Ventilation??

[gbrasseur]

Hi Inspectors,

I just looked at this house, which is Brand new construction. I am puzzled on something. There are no soffit vents, and there are no roof vents on the house! Also, there are no gable vents.

Am I COMPLETELY missing something,or is this just plain bad construction. I was under the assumption that you needed 1sq foot of ventilation for every 150sq feet of attic.

The house is a rancher with a finished basement. I looked in the attic and did not see any kind of venting system? I do not know what code is in this area on this, but it just seems wrong any way you slice it.

What are your thoughts on this, I would appreciate your input!

[David P. Valley]

It appears that there are two square aluminum roof vents installed (1st pic) 1 high and 1 low, but IMO... all new construction should have Ridge and soffit/drip edge vents.

I would recommend improvement/upgrade to the attic ventilation (ridge & soffit/drip edge vents.

[rskinner]

I came across the same situation a while back and found no insulation in the attic either. I found out that all the walls, ceilings and roof are insulated panels and do not need ventilation except for dryer and bathroom exhaust vents. What did you find in the attic?
The pics look like the facia's are very tall making me wonder if insualted/foam panels were used.

[gbrasseur]

Robert,
There was blown insulation in the attic.

David, those are bathroom vents to my understanding. Do you think they are not?

[dfogleman]

The roof should be ventilated, check a shingle warranty...unventilated attics shoot the factory warranty. Heat kills shingles! Moisture, well we know what moisture can do, but it won't hurt the shingles though. A proper attic ventilation system will perform for the home year 'round.

You are correct about the attic having 1 sqft of vent for 150 sqft of attic space, this is when the attic insulation has a vapor barrier it doubles (1 sqft to 300 sqft) if no vapor barrier is present.

The target for a balanced system is 18 sq inches of Net Free Air Space per linear foot, this is to be split evenly between eave and peak. In the event that the roof does not have an adequate lenth to the peak such as a hip roof then the ridge ventilation should be excluded and a power attic vent should be installed, preferrably one that operates with a dual control...thermostat and humidistat. Not all products meet these requirements, check factory specs on the products...I recently counted the holes on a vented soffit product and did the math based on the size of the holes and guess what the eave did not have adequate intake (Net Free Value was approx 6 sq in per foot) this product could void a factory shingle warranty.
The eaves in the pictures look different, I would be curious how they are finished, there are installations that allow the intake of the vent flow to travel up the back of the eave face board. The space that is needed is normally 3/4" at the intake point, larger depending on the media that is used to keep insects out.

Good references to ventilation requirements are AirVent and DCI products.

I am curious about the the ventilated panels not needing ventilation, I would like to know more about this for my knowledge bank. The log homes with cathedral ceilings I re-roofed in the past were built with no ventialation and had a foam insulation. I replaced these systems with a ventilated foam panel that was laminated to OSB and provided chanels for the air to travel to provide the vent flow.

[gbrasseur]

I was curious also Don, about the ventilation panels.

[David P. Valley]

Here's the newest fascia ventilation system
http://www.fasciadivision.co.uk/vent_sys.htm

But I still want to see an outlet (ridge) vent at the top portion of the roof.

[David P. Valley]

Originally Posted by gbrasseur

David, those are bathroom vents to my understanding. Do you think they are not?

If there were hoses attached to them, then "Yes" they are bathroom vents.

What did you see while you were in the attic? Were they open or did they have hoses attached to them. Most bathroom vents get installed into the soffit area.
Attachment 7996

[Barry Adair]

For information on unvented/conditioned attic and crawlspaces please see this:
http://www.buildingscience.com/resou...on_venting.pdf

or seach for your area through these: http://www.google.com/custom?domains...ingscience.com

Top ten is a good place to start
http://www.buildingscience.com/topten/south.htm